BMW: 2013

Thursday 26 December 2013

Replacing your BMW Fuel Filter

One of the basic maintenance projects that you should perform on your BMW is the replacement of the fuel filter. I recommend that you replace your fuel filter about once a year, or ever 10,000 miles. It seems that with today's fuels, there always seems to be some gas station that has problems with dirt or grime in the gasoline that can clog your tank. I don't think quality control with gasoline stations is really what it used to be. Needless to say, I try to replace all the fuel filters at least once a year.

Changing the fuel filter is not a job that I relish. There is an almost guarantee that you will spill at least some fuel on the ground and yourself as you swap out the fuel filter. Perform the replacement in a well-ventilated area. That means outdoors or in your garage with a few large fans blowing air both in and out. Have a fire extinguisher handy, wear rubber gloves, eye protection, and have a few rolls of paper towels handy.

The fuel tank should be as low as possible - drive around the car until the gas tank is almost empty. This will minimize problems if something should happen to go wrong.

The first step is to jack the car up. See our Pelican Technical Article on Jacking Up for more information. I recommend that you only jack up the front of the car, and leave the rear on the ground. This will minimize any fuel flowing forward to the front of the car from the tank. The E36 3-Series BMWs have a semi-intelligent design when it comes to fuel flow. The fuel pump is located in the top of the tank, and pumps fuel out the top as well. Why is this good? Well, when you go to change the fuel filter, you can pull out the fuel pump relay, crank the car a few times, and be assured that fuel isn't going to flow everywhere if you make a mistake. Some cars have a gravity-fed system that takes fuel out of the bottom of the tank. With these systems, you have to disconnect the line, and clamp it very quickly, otherwise, the entire tank of gas will empty out!

Now, pull out the fuse for the fuel pump (Figure 1), and crank the engine a few times. In general, this is fuse #9 on the E30 cars, and fuse #18 on the E36 cars - check your individual model first, prior to pulling the fuse. Removing this fuse and turning over the car will help to reduce some of the fuel in the system. Unfortunately, you can't get most of it out, and some will spill when you disconnect the fuel filter. In addition, the filter itself will be full of fuel too.

Now, crawl underneath the car. The fuel filter is generally in the same location for all of the cars - located on the left side of the car, somewhat underneath the engine (Figure 2, Figure 3, and Figure 4). Also see Figure 5 for a photo of what a brand new fuel filter should look like. You now want to disconnect the line. I typically like to clamp the fuel line before disconnecting it as this will minimize the amount of fuel that will leak out. However, you have to be very careful clamping the line, otherwise you may damage it. A large c-clamp works well, or you can use Vice-Grips, but only if you cover the jaws with several layers of duct tape - this will minimize the amount of damage you will do to the line. It's okay to squeeze the line closed tight, but you don't want to score, rip, or crack it with your clamping tools.

With both the inlet and the outlet to the fuel filter clamped, release the hose clamps on either side. Have a small pail or bucket handy to catch the excess fuel when you release the line. Sometimes the line will slip off, but some times it will require some coaxing. I recommend using a small crescent wrench that fits nicely around the fuel pump inlet, but is too small to fit around the fuel line. Wedge the wrench against the filter housing, and you should be able to pry off any stubborn fuel line. If all fails, and you simply cannot pull the line off of the filter, then make a small 1/4" cut along the length of the line and try again. Continue making cuts until you can remove the line. This will minimize the amount of line that you will have to cut in order to get the filter off.

When the line is released, expect quite a few ounces of gasoline to be coming your way. Be prepared (gloves, eye protection, paper towels, bucket, and a well-ventilated area). Take the filter out (it's held in with a hose clamp), put it in your bucket and take it, and any left over or spilled gasoline outside of your garage immediately. Let the garage sit empty for about 15-20 minutes before you re-enter - it will take about that long for the fumes to clear. Then, simply reattach the new filter in place of the old one. Tighten the clamps tight, but don't clamp them so tightly that you strip the clamps.

Replacing your BMW Fuel Filter

The fuel tank should be as low as possible - drive around the car until the gas tank is almost empty. This will minimize problems if something should happen to go wrong.

Replacing your BMW Fuel Filter

The fuel tank should be as low as possible - drive around the car until the gas tank is almost empty. This will minimize problems if something should happen to go wrong.

BMW E30 Coolant Temp Sensor Replacement

Keep in mind that this article is specific to my 325is, however the article applies to all BMW models in general. That said, I decided to do a small tech article showing how to replace this sensor and hopefully provide you with some insight on this common idle problem and how to correct it.

The first step is to open the hood and locate the sensor. In this case, the sensor is located in the thermostat housing. Locate the sensor and remove the electrical connection from the top by pushing in the metal clip and pulling it off.

Now use a 19mm deep socket to remove the old sensor. It should come out with no resistance, however if there is a lot of corrosion around the switch, it’s a good idea to clean all this off prior to removing the sensor. I’ve heard a lot of different ways to remove rust, but believe it or not, the best way I’ve found is to go to your local vending machine and buy a can of Coke. A toothbrush and some Coke will clean up just about any rust you can imagine. (this is another convincing argument why soda pop is bad for you.) just get it clean and pull the old sensor out.

Take a look at the new and old sensors side by side. You can see the discoloration on the old sensor. This is most likely an indication that years of hot coolant passing over the sensor has eventually caused oxidation on the surface, which in turn causes the sensor to build up internal resistance, causing it to eventually fail.

Now look at the thermostat housing make sure the area around the housing is clean and free of any dirt. You don’t want this to get into the coolant. Just wipe away any grime or grit. Now, place the new sensor in the housing and use the socket to tighten it in place. Do not over tighten, as you can damage the threads. Now, reconnect the electrical plug for the sensor and start the car. Your idle should now be between 700-900 RPM and smooth like Shaft.

You may also want to bleed the cooling system to get rid of any air that may have entered the system. There is a small screw on the top of the thermostat housing. Start the car and loosen the screw. This will allow any air to bleed out. When you see straight coolant coming out, the system is bled.

BMW Radiator Replacement

Proper maintenance of your coolant will go a long way towards extending the life of your radiator. The cooling systems on most cars are often very neglected, as most owners don't know much about them. See the Pelican Technical Article on Cooling System Flush & FAQ for more information. The most vulnerable components in the entire system are the radiator and the heater core, as they tend to be damaged by corrosion and electrolysis. Poor maintenance of the system can result in the build-up of corrosion elements in both the radiator and heater core, creating clogs and leaks that decrease cooling performance. If the engine overheats, the additional heat from the coolant can also damage sensitive plastic attachments and components.

When replacing your radiator, you want to make sure that you replace it with one that meets or exceeds the OEM cooling standards. BMW cooling systems are infamous for overheating problems. Therefore, it may be a wise idea to install an aftermarket performance radiator that performs a better job of cooling than the standard OEM one. I also recommend replacing your water pump, radiator hoses, thermostat, and any hose clamps too. All of these components can be damaged by a cooling system that has overheated. It's also a good time to swap out your old belts.

Okay, the first step in replacing your radiator is to remove all of the coolant from the system. See the Pelican Technical Article on Cooling System Flush & FAQ for more information. Now, we need to gain access to the radiator. Remove the front plastic panel that covers the front inside part of the engine compartment (Figure 1). Four screws hold this panel to the car. Now, it's time to remove your cooling fan. You will need a 32mm wrench, and a special fan removal tool (Figure 2). Unfortunately, I have not found an easy method of removal that does not require the use of this tool. The tool holds the two pulley nuts enabling you to remove the fan pulley nut (Figure 3). Holding the fan pulley steady with the tool, twist and remove the fan nut (Figure 4 and Figure 5). It is important to note that this nut has reverse threads, and needs to be turned clockwise to loosen it (Figure 6).

Now, you need to remove the fan frame with the integrated reservoir. The cooling fan housing frame is held in with small plastic rivets (Figure 7). Pop these out to loosen the frame from the radiator (Figure 8). You will have to disconnect the overflow hose prior to removing this frame (Figure 9). Also attached to the frame is the reservoir overflow hose. This hose winds around to the left side of the car, and needs to be disconnected near the power steering pump (Figure 10). This hose is shown disconnected in Figure 11. Now, disconnect the coolant level sensor (Figure 12). With all of these hoses and connectors disconnected, you should be able to remove the fan frame / reservoir from the car (Figure 13).

With the frame out of the way, now disconnect all of the hoses that are linked to the radiator. There are two large hoses, one on the top left side of the car, and one on the lower right. Loosen the hose clamp on the top left hose (Figure 14), and then pull it away from the thermostat housing (Figure 15). Figure 16 shows both sides of this hose. Now, disconnect the lower radiator hose on the right (Figure 17). Then, remove the electrical connector for the radiator temperature sensor (Figure 18).

With the hoses disconnected, now disconnect the automatic transmission lines, if you have an automatic transmission in your car (Figure 19). See thePelican Technical Article, Replacing Automatic Transmission Lines for more details.

The radiator is held onto the chassis of the car with odd, complicated plastic clips. These are very difficult to remove, and you may end up breaking them when getting the old radiator out (Figure 20 and Figure 21). Using a screwdriver in the center of the clip, pry it out from the chassis and the radiator. You may have to play with these clips for a short while to remove them. With the clips removed, the radiator should no longer be attached to the car (Figure 22), and can be easily lifted up and out of the engine compartment. Figure 23 shows the radiator removed from the car. The small radiator attached to the center of the main radiator is the automatic transmission cooler. Make sure that you have a catch bucket (kitty litter boxes work very well) to capture all of the excess coolant and automatic transmission fluid that will spill out (Figure 24).

Figure 25 shows what the engine compartment looks like with the radiator removed. When you install your new radiator, or reinstall your old one, make sure that it sits firmly on the rubber mounts attached to the chassis (Figure 26). It is possible to install it slightly cocked if you don't pay attention to these mounts. Figure 27 and Figure 28 show the radiator reinstalled in the car. If you damaged your plastic clips removing the radiator, be sure to replace them with new ones. Reattach all of the hoses and connections. Use new hoses on the large upper and lower radiator hoses. If your clamps look worn, then replace them while you're in there too. Only use clamps specifically designed for large rubber hoses - some generic hose clamps can cause chaffing on the rubber when tightened. Then button up the front cover (Figure 29). Replace all of the coolant and bleed the system according to the thePelican Technical Article on Cooling System Flush & FAQ.

BMW Water Pump Replacement

BMW cooling systems have been known for being troublesome for quite some time. One of the principle areas of failure are the thermostat and water pump. Some of the old style water pumps had a plastic impeller that has a tendency to become brittle and break off after many years of service. BMW has replaced the plastic impeller in recent years with a metal one. If you know that you have a plastic impeller in your car, then you should replace it as soon as possible. Overheating problems are common on these cars, and if your engine overheats, you may find yourself having to replace your head gasket, which is not cheap.

Begin the process by gaining access to your water pump. This requires the removal of the fan and belts, as well as the removal of all coolant from the system. See the following technical articles for instructions on how to get to this point:

With all of your equipment removed, the front of your engine should resemble Figure 1. Remove the fan pulley from the water pump - it is held on with four small nuts. Your water pump should now resemble Figure 2. Loosen the four nuts that hold the water pump to the engine block. Then, using a rubber mallet, softly tap on the side of the water pump (Figure 3). It should separate from the block after a few taps with the rubber mallet (Figure 4). Once the water pump is loose, you should be able to pull it out of the engine block.

Figure 5 shows a brand new water pump with the metal impeller. Figure 6, Figure 7, and Figure 8 show the differences between the plastic one and the metal one. There is no functional difference - they will both pump the same amount of coolant through the system.

With the pump removed, check the inside bore where the water pump fits for debris or corrosion (Figure 9). With a wire brush, remove any corrosion or debris that may have built up there (Figure 10). Install the new water pump using a new o-ring. Place a little bit of white lithium grease around the o-ring to ensure that you have a good seal, and to ease installation of the pump into the engine block (Figure 11). Install the new pump and tighten down the four bolts that attach it to the block. Torque them to 8 ft-lbs - no tighter.

Figure 12 shows your new water pump installed. Reattach the fan pulley, the fan, and all of your belts. Refill and bleed the system, and you should be good to go! While replacing your water pump, it's also a good time to replace your thermostat, while you're in there.

BMW Radiator Replacement

BMW E30 3 Series Ignition System Tune-Up

In this tech article I will go over the incredibly simple steps needed to tune –up your vehicles ignition system. While this article is specific to my 325is, it applies to all BMW models in general.

That said let’s begin. First, disconnect the battery. This is important as we will be working around electricity, and you don’t want that random voltage spike damaging sensitive components on your car. Even worse, you don’t want a surge of power coursing through your body.

Once disconnected, open the hood and look at the passenger side of the engine. You will see the following components:

Ignition Wires (called HT leads in the UK and other parts of the world)

Spark Plugs

Distributor Cap

Distributor Rotor (under the distributor cap)

During a normal ignition tune-up all of these items are replaced. It’s recommended that you carry out this procedure at 80,000 miles, however problems such as fouled pugs and worn rotors may prompt you to carry this procedure out earlier.

The first step is to look at the spark plug wiring loom that runs parallel to the valve cover. You will see two 10mm nuts holding onto the valve cover. Remove these nuts and pull the loom clear of the studs. Next, disconnect the wire going to the coil, which is mounted on the inner passenger fender.

Now pull each wire off each spark plug. They should come right off, however if they seem stuck, just give the connector a twist and it should free it up. Next, look at the distributor at the front of the engine. Remove the plastic cover over the distributor by unclipping it. Now, use a small 10mm open-end wrench to remove the three small bolts that hold the distributor cap in place. Remove the wires and cap together. Now look at the inside of the cap. You should be able to see the small contact points inside. They should appear slightly worn. If they show signs of pitting and/or burning, you will need to replace the cap. This wear is normal. It is the by-product of the voltage coming from the coil, then being distributed out to each individual spark plug. This corrosion and pitting is normal for a used cap. Sometimes, in a pinch, you can sand down the contacts and this will suffice, the same applies to the distributor rotor as well. Now, remove the three 10mm bolts holding the distributor rotor to the engine. Take a look at the contacting edge of the rotor. As before, if it shows any pitting or burning, it must be replaced.

Now, we will remove the spark plugs. I’ve found that on the M20 engine, all that is required is a spark plug socket, 4 inch extension and a ratchet. Now, remove the spark plugs and inspect them. A normal, well-used set of plugs should appear to have a tan/grey appearance. If they appear any other way, it’s a likely indicator of possible engine problems. Here’s a small list of what to look for on your plugs.

Plug Condition	Possible Causes
Grey/Tan color, electrode rounded off	Normal Wear
Oily deposits, Oil leaking into cylinder, possibly	Worn valve guides or piston rings
Carbon deposits, ash on electrodes	Rich mixture, poor ignition, over-use Of fuel and/or oil additives
Blistered electrode, white appearance	Lean mixture, Overheating, vacuumleaks

Once you have inspected the plugs, make a note of whatever mechanical repairs or adjustments must me made to the car to correct these problems. Keep in mind that spark plugs are usually a great indicator of how well your engine is running. Many times, I have made mixture and timing adjustments on older cars just by looking at the plugs.

Before we install the new plugs, check the ignition gap. Most plugs nowadays come “pre-gapped” however; I always check the ignition gap. There’s always that one time you get the spark plug that missed the eye of the quality inspector on the line. Most ignition gapers are available at your local auto parts store for usually under a buck. Check the gap by sliding the tool in between the contact arm and the electrode, and slide it around until it drags slightly, now read the mark on the side. This will give you the gap. The factory gap for the 325 6 cylinder is 0.7mm or 0.027 inches. Use the gapping tool to carefully bend the contact arm either closer to or away from the electrode to adjust the gap.

Now, put a small dab of anti-seize on the threads of the spark plugs and carefully thread them back into the cylinder head. Be very careful while doing this, as the cylinder head is aluminum and it’s very easy to strip the threads. Once seated, tighten the plugs down snug but do not over tighten, or you will be soon learning how to install a Heli-coil.

Take the new distributor cap and lay it out next to the old one with the wires still attached. We will now want to open up the new wire holder and determine which connection goes to where based on the old cap/wires. It is crucial you have these wires oriented correctly. This is what is commonly referred to as the vehicle’s firing order. In this case, the firing order on the 325 is 1-5-3-6-2-4 What this means is the voltage from the coil will travel through the distributor, down through the rotor, and when the rotor turns to the number 1 cylinder contact on the distributor cap, it sends the voltage down through the spark plug wire to the spark plug, which in turn, ignites the fuel/air mixture in the cylinder, causing the engine to run. The rotor will now turn in sequence to the number 5 contact, then repeat the procedure, then rotate to the number three cylinder contact, then 6 and so on, til it rotates back to number 1.

To make sure it is correct, lay out the old wires next to the new wires and cap. Each cylinder on the engine has a specific length, so all wee need to do is compare the lengths of new wire to the old, and connect them to the new cap as they are installed on the old cap. Once you have the new wires on the new cap, place the wires back in the holder.

Now, take the new distributor rotor and bolt it back on to the distributor shaft using the three 10mm bolts. Make sure that the dust shield is correctly in place and place the new distributor cap/wires back onto the housing. It is indexed so that it will only go on one way. Once in place, re-install the 10mm bolts that hold it on. Now place the distributor cover back in place and clip it on.

Next, take the wire holder and place the two brackets over their corresponding studs on the valve cover. Once on, re-install the two 10mm nuts and tighten them down. Once the wire holder is secured, take each individual wire connector and slip it on each spark plug. You should be able to feel the connector seating on the plug as you push it on. Don’t forget to install the coil wire as well.

The last step is to re-connect the battery and start the car. You should notice that the car has a little more pickup and runs a bit smoother.

BMW Engine Management Systems

The Motronic system (also called the digital motor electronics, or DME) is hands down the best overall fuel injection system when you consider price and performance. Ignition timing and fuel delivery are controlled by a digital map recorded in a removable chip within the main engine management (DME) computer. The computer takes input from a variety of sensors on the engine—cylinder head temperature, altitude (ambient air pressure), crank angle, throttle position, exhaust gas oxygen (mixture), ambient air temperature, and mass airflow—and adjusts engine functions accordingly. The DME chip is programmed by the factory with a map of certain performance parameters (mostly conservative, so the engine will react well under a host of varying conditions). Major changes to the engine (including different camshafts, exhaust, etc.) require an updated map to take full advantage of these modifications. Failure to update the Motronic system when significantly altering your engine may actually result in decreased performance, as the original system is finely tuned to supply the correct timing and fuel injection values for a stock engine configuration.

     Each factory Motronic system is matched directly to a specific engine configuration. Because of the proprietary nature of the Motronic system, there aren’t many changes you can perform without updating the DME chip. To gain the maximum benefit from engine modifications, either upgrade the DME chip or install a programmable aftermarket engine management system.

     Similar to the Motronic system, there are several complete aftermarket engine management systems that integrate fuel delivery and ignition system control. Electromotive and Motec manufacture two of the most popular systems for BMWs, although the market is expanding with many more choices as well. While these systems will squeeze the maximum performance out of your engine, they are not for the faint of heart, are technically challenging, and cost a pretty penny. They are without a doubt the most flexible of any fuel/ignition systems and will enable you to extract every ounce of power from your engine if you spend the time tweaking the system. Most are programmable from a laptop computer and can even interact with your computer both ways, giving you performance data and feedback from the engine as you run it through its paces. These systems cost anywhere from $3,000 to $10,000; however, they are usable on nearly any size BMW engine in any configuration.

     With the option of complete engine control, total power optimization becomes a reality. The latest engine management system from Electromotive is the TEC3r (Total Engine Control, Version 3), shown in Photo 1. This single-plug system costs about $2,500. It is far more advanced than previous versions and offers almost unlimited flexibility in designing your fuel and ignition systems.

     TheTEC3R system has a proportional air-to-fuel ratio table that allows you to systematically control the mixture from idle to full throttle. According to modern fuel injection theory, fuel and air combustion achieves its maximum efficiency at a ratio of 14.67:1. Although this ratio may be optimal for good fuel economy, it’s not best for maximizing power. On a normally aspirated engine at full throttle, maximum power is achieved with an air/fuel ratio set at about 13.8:1 to 14.0:1. On boosted engines, this maximum power ratio is closer to the range of 12.2:1 to 12.4:1. Using the variable fuel ratio characteristics of the TEC3r, you can create one set of programs for the track, where fuel delivery and optimum performance are critical, and another set for the street, where maximum fuel efficiency is desired. Because the TEC3r system senses engine load via a manifold absolute pressure sensor, the system can determine whether you’re cruising on the highway or driving on the track. One single program can also be designed for both applications.

     The system consists of a separate electronic control unit (ECU) and ignition coil packs. These coil packs, or direct-fire units (DFUs), deliver a full-charge spark up to 15,000 rpm. For a BMW inline six-cylinder engine, use a three-coil assembly. Each coil fires a spark for two cylinders that are opposite from each other in the firing order. By using a separate ignition coil for each pair of companion cylinders, the time available to recharge the coils increases by a factor of three (on the six-cylinder BMW engine). This configuration produces full spark energy while delivering spark duration up to 2 milliseconds at 6,000 rpm. This duration is more than 10 times longer than most capacitive discharge units and directly translates into better combustion and more power. For coil-on-plug engines, like the BMW E36 inline engine, stock ignition coils can be used in place of the DFU.

     Each coil pack is wired into two cylinders that are opposite of each other in the firing order (1 and 6, 5 and 2, 3 and 4). The ignition portion of the TEC3r system is wired so that the companion cylinders fire at the same time. Each coil fires a plug on the compression stroke for one cylinder and on the exhaust stroke for the companion cylinder. This produces what is known as a “waste spark” on the exhaust stroke of the companion cylinder. The cylinder that has compressed the air/fuel mixture receives a higher voltage spark than its companion cylinder, because the mixture creates an environment around the spark plug that offers a more conductive path. The majority of spark energy is delivered to the compressed cylinder. A small amount of spark voltage is directed to the cylinder on its exhaust stroke. This waste spark has no effect at all on the performance of the engine. Direct connection from the coil to each of the cylinders eliminates sending the spark through the distributor cap and rotor (on early cars), which can cause cross-firing and other distributor-related performance problems. In addition, computer-controlled custom advance/retard curves eliminate any mechanical problems that may occur with centrifugal or vacuum timing adjustment.

     The TEC3r ECU is dynamically programmed with easy-to-use software that comes with the system. The Tuning Wizard in WinTec 3.0 software allows you to create an instant engine profile in just a few steps (see Photo 2). By inputting all the parameters of your engine, you can start with a good base profile from which to make modifications. Mapped programs download to the ECU via a computer serial cable and can be updated, changed, or restored at any time. The base programs can be tweaked to get about 90 percent of the full power potential out of the engine. To achieve the final 10 percent, do extensive track testing or run your engine on a dyno.

     The TEC3r system works by sampling the values from sensors in the engine and comparing them to various tables that control fuel delivery and ignition timing. These sensors consist of the following:

Oxygen sensor: measures mixture by measuring the exhaust gases

Manifold absolute pressure sensor: measures pressure, while compensating for altitude changes; you can also substitute a mass airflow sensor instead of the MAP.

Knock sensor: detects and measures detonation caused by poor fuels or too much timing advance

Crank angle sensor: measures rpm and crank location

Throttle position sensor: measures position for idle control and how quickly the pedal is depressed for fuel enrichments (or deceleration cut-off)

Cam angle sensor: detects cam timing for true sequential mode fuel injection

Coolant sensor: measures engine temperature for warm-up enrichments

Manifold air temperature sensor: measures air temperature entering the engine for mixture compensation

Idle speed control: controls idle speed for warm up and air conditioner

     These sensors work in conjunction to measure and create a picture of the engine conditions at any one point in time. The ECU takes the sensor readings and translates them into formulas for delivering fuel and firing sparks. Using advanced data-logging features, the sensor readings and the results of the ECU changes are recorded, snapping a picture of all the engine functions at any point. The data can be recalled for analysis and used as a reference for future programming of the ECU.

     The TEC3r operates in either phased sequential or true sequential mode. Phased sequential means the fuel injectors are activated multiple times per crankshaft cycle—once on an open valve and once on a closed valve. Early versions of the Motronic system were designed as phased injection systems. The fuel injectors on one-half of the engine would all open and close together. They share the same wiring harness and are electrically controlled as a group. True sequential injection means that each injector is activated in close coordination with that cylinder’s ignition cycle. Fuel squirts out of the injector in precise coordination with the opening and closing of the intake valve. Fuel is never injected into the cylinder head when the valve is closed. The TEC3r, operating in true sequential mode, injects fuel only when the intake valve is open, which smoothes out the engine idle and creates a cleaner-running engine. At higher rpm, phased sequential and true sequential modes show virtually identical performance, as the injectors are firing almost continuously.

     Another advantage to the TEC3r system is its flexibility; it can be used on just about any engine. Its ability to run engines up to 12 cylinders means it can be moved from one engine to another as you upgrade. It’s a very worthwile investment that can grow with you even if you upgrade your engine or your car.

     Pushing the limits of ultra-high performance, the TEC3r also has four general output parameters (GPO) that can be controlled by any number of engine conditions. For instance, the system can automatically turn on cooling fans or open electric thermostats if the engine temperature or rpm increases past a certain threshold, or provide the driver with a custom-designed shift light on the dashboard. In what could be the ultimate performance system, the TEC3r can control a variable turbo boost valve coupled with a knock sensor. This would allow you to run the maximum possible boost on a turbo or supercharged engine while actively monitoring and correcting for detonation. The engine management system can control this boost pressure, engine timing, and a host of other variables to achieve the highest possible boost without inflicting collateral damage. This system would be able to dynamically compensate for any octane fuel—automatically adjusting the timing and air/fuel ratio to squeeze the most power out of the engine.

     The TEC3r system can run in an open- or closed-loop configuration with respect to air/fuel mixture measurement. Open-loop mode is useful for racers who run leaded race fuels that cannot be used in conjunction with an oxygen sensor. In this mode, the system reads measurements from its sensors, and then compares the readings to its internal program maps. Spark and fuel mixture are controlled using these maps, without correcting for changes that would normally be measured by the oxygen sensor.

     The TEC3r is also able to self-diagnose problems with the engine’s sensors. The ECU has a check engine warning lamp that indicates if any of the engine’s sensors are producing faulty signals. The error codes isolate the exact problem and can be quickly downloaded from the ECU to diagnose the problem.

     The TEC3r is not specifically designed for the BMW and thus requires some adaptation to fit BMW engines. Sias Tuning manufactures a plug-and-play adapter kit that allows you to slide in the TEC3r unit in place of a Motronic DME, and replace the mass airflow (MAF) sensor with a manifold air pressure (MAP) sensor. The Sias Tuning kit is a good starting point for entry into the world of engine management. However, the plug-and-play adapter is somewhat limited in scope, because it uses all of the GPOs (general-purpose outputs) to control the various components of the car. The big advantage to an adapter like this is that you can simply reinstall the stock DME unit if you need to have the car checked for emissions. I recommend starting with an adapter kit. Then, if you seriously modify the engine, you can upgrade the engine’s sensors and create a specific wiring harness for the system.

Why invest in one of these systems if you haven’t significantly modified your engine? Because they are really neat to play with, and you can custom design your own fuel and ignition maps. You probably won’t squeeze out any more horsepower than you would with a good aftermarket performance chip, but you will have fun playing around with the unit. On the other hand, if you want to design the ultimate engine, you need to install some type of engine management system. With a system like this, you can design and build any engine combination you want. Whether you desire a supercharged, boosted engine, or a super-high-compression-ratio engine that runs on pump gas, the engine management system will be able to control and optimize it. The possibilities are truly endless and unbounded.

BMW Intake Manifold Removal

Let me start off by congratulating the BMW engineers for squeezing the E36 six-cylinder engine into an almost impossibly tight spot. It is quite a remarkable packaging job, considering they did it in the early 1990s when all they had were computers with 386 processors and rudimentary 2D CAD programs. Yet their success makes it a big pain for mechanics who work on these cars—it’s a tight squeeze, and you have to remove a lot of stuff to remove the intake manifold.

     The best way to learn how to remove the intake manifold is to carefully follow along with these pictures. This task includes one of the steps in the head gasket replacement (Project 17), so a number of other items have already been removed (fan, radiator, belts, etc.). If you’re just pulling the intake manifold, you don’t need to remove these other items.

     For this project, I strongly recommend that you get a digital camera and take about a hundred photos of the disassembly process. If you have any questions as to how it was put together beforehand, you can easily refer back to the photos. As an additional resource, the companion CD-ROM to this book (available at www.101Projects.com) contains approximately 300 more photos of the manifold removal and installation process.

     Before you begin, let the car sit for about six hours before working on it. The pressure in the fuel lines should have dissipated somewhat, and the car should be stone cold while you’re working on it. Disconnect the battery (see Project 84), as you will be working very close to the starter, which has live current running to it at all times. You will also be disconnecting fuel lines near this connection and don’t want to risk any sparks. Additionally, remove the gas cap from the gas tank to relieve any pressure that may have built up inside the tank from expanding fumes.

     Since installation is simply the reverse of removal, just hook everything back up—but carefully inspect the intake boot for cracks prior to doing so. Consider replacing the intake boot while you’re in there, as it may start to crack and break once you’ve disturbed it. Also, watch out for the lower rear manifold mounting bracket, as it can be very difficult to reattach

BMW Rod Bearings & Oil Pump Nut Replacement

The connecting rod bearings in BMW engines transmit 100 percent of the load from combustion to the crankshaft. As a result, the bearing surfaces do not wear evenly. The side of the bearing facing opposite the piston tends to get the most wear, because the rod pushes on it with a huge amount of force when the cylinder fires. On the opposite side of the power stroke, the same rod pulls the piston and rod assembly back toward the crankshaft, creating wear on the opposite side. These push–pull forces on the crankshaft bearings are exactly opposite each other and create wear patterns on opposite sides of the bearing journals. BMW connecting rods, like the crankshaft itself, are robust parts. Rods typically become damaged when a more basic problem, like low oil pressure, caused by high heat or simply low oil levels, causes the rod bearings to run dry. The rod bearing journals are some of the last components to receive oil, and thus are often the first to run dry when the engine oil level runs low. The result is catastrophic failure, as the rod itself crushes and squeezes the rod bearings against the crankshaft.

     If your engine has suffered from a loss of oil pressure, the first thing I recommend you do is replace your rod bearings. They are the one component most likely to be damaged by low oil pressure and the one component that, if worn, will result in complete engine failure. When most people think of bearings, they think of ball bearings like you would find in the wheel of a bicycle. The rod bearings are very different; they are basically a strip of curved metal that an oil film floats on. When the engine is running perfectly, the connecting rod bearing never touches the crankshaft, as thin oil molecules are suspended between the bearing and the crankshaft. The only time they might touch under normal circumstances is when you first start up the engine and there’s not much oil pressure built up yet.

     If your engine runs low on oil pressure, the crankshaft will ride on the actual metal bearing strip with no thin film in between. This accelerates the rod bearing wear significantly, causing the bearings to overheat and disintegrate in a matter of minutes. If the engine hasn’t seized and you’ve driven the car with the low oil pressure lamp on for even a short while, you should bite the bullet and replace the rod bearings as soon as possible. A catastrophic drop in oil pressure might be caused by hitting a large rock on the freeway that punctures the bottom of your oil sump, or having the oil pump nut come loose on your E36 six-cylinder engine (more on this later).

     Rod bearing replacement is generally straightforward. The toughest part of the procedure is getting to the bearings themselves. On the E30 and E36, this involves removing the front suspension, front axle support bar, steering rack (Project 59), and lower sump oil pan (Project 19). Once all of this equipment is out of the way, you have ready access to the rod bearings.

     Begin by rotating the engine so you can reach the rod bolts. The rod bolts can be accessed in the following sequence: 1 and 6, 3 and 4, and 2 and 5. Turn the crankshaft over so each pair moves to its lowest position. Use a socket and driver on the front crankshaft pulley nut (see Photo 3 of Project 17). Remove the two rod bolts from each of the two rods, and gently pull off the rod end cap. If it sticks on the end of the rod, tap it lightly with a very small hammer. With the cap removed, gently push the other rod half up into the engine until the rod can clear the crankshaft journal. Place a small strip of cardboard against the surface of the crankshaft—you don’t want to scratch the delicate polished surface of the crankshaft with the edge of the rod.

     Inspect the rod bearings when you remove them. They should be a dull grey, with no indications of wear or discoloration. If they are shiny, if you see brass-colored metal, or if the bearings are missing chunks or pieces, they are surely worn and need to be replaced.

     Replacement rod bearings must be matched to the crank. If you use a crankshaft that has had rod journals reground, you will have to use oversized rod bearings. Measure the rod journals on the crank before you order any replacement rod bearings.

     Using a clean-room wipe and isopropyl alcohol, carefully clean each rod bearing (see Photo 4). Install each bearing into the rod cap and rod half. Depending upon which engine you have, there may be upper and lower bearing shell halves (blue for the top side and red for the lower side near the rod cap). Using a clean-room wipe and isopropyl alcohol, clean all oil and residue off of the rod bolts and nuts. Then install the new rod bolts into the cap. Apply a generous, but even, layer of assembly lube to the rod bearing. Spread the assembly lube across the rod bearing with your finger while wearing powder-free latex gloves. If you don’t gloves, wash your hands first with nonpumice soft soap and make sure they are clean of any dirt or debris. Lubricate both bearing halves, and wipe a small amount around the sides of the big end of the rod to help lubricate any side contact the rod and crankshaft might see before adequate oil pressure is achieved.

     Each rod is stamped with a unique number, and rods and their matching caps must be kept together. Make sure the numbers stamped in the rod butt up against each other. If you have the cap aligned correctly, with the numbers lining up, the rod bearing tangs located on the edge of each bearing will also butt up against each other. Double-check that you have properly lubed all the bearings and lined up the rods with their matching caps before you begin to torque the rod nuts to their final values.

     Rod nuts and bolts are one-time-use parts designed to be tightened to their torque values only once. Always use new rod bolts and nuts when replacing your rod bearings. When tightening the rod bolts, carefully follow the torque values and use a calibrated torque wrench. Rod bolt torque values vary considerably; see www.101Projects.com for a listing of torque values and tightening procedures. Most procedures involve tightening the rod bolt to a specific torque value, and then further tightening the bolt a certain number of degrees.

     With the new bearings installed, follow BMW’s engine break-in instructions. Disconnect the fuel or DME relay, and allow the car to build oil pressure by turning over the starter in 10-second increments. Repeat this step at least three times to build oil pressure in the engine. Breaking in an engine involves all of the parts in the engine beginning to wear together, finding their groove. Close-tolerance parts actually wear and machine themselves into proper alignment with their counterparts over time. For the first 1,200 miles, do not exceed engine rpm of 5,500 or road speed of 105 miles per hour.

     Interestingly enough, there is a factory recall notice (SI B 11 04 04) that dictates rod bearing replacement on the E46 M3 with the S54B32 engine, produced from February 12, 2001, through May 22, 2003. The original bearings in these engines were prone to failure if the engines were driven at high rpm for extended periods of time (exactly what you’d expect to do to an M3). The design of the S54 motor is very similar to the earlier inline six-cylinders, and the rod bearing replacement procedure is the same. The factory recall involves replacing the bearings and an update to the factory engine management software (DME) to restrict rpm when the car is in lower gears.

Oil pump nut

     A relatively new failure mode is occurring on some six-cylinder BMW engines, like the ones used in the E36 series. The oil pump gear attaches to the engine crank by a chain and a sprocket held on with a small reverse-thread nut. There have been many recent reports of this nut coming loose and falling off the sprocket. As a result, the sprocket becomes loose and can separate from the oil pump, leading to zero oil pressure in the engine. This can be catastrophic to the rod bearings, which are typically the first components to fail.

     It hasn’t been determined what causes this loosening of the nut. Some people I’ve spoken to seem to believe the odds of it falling off may be increased by aggressive driving and go so far as to suggest it happens when the chassis of the car is spun around on the pavement (like at the race track). Whatever the cause, this very serious problem seems to be affecting many more cars as they age and are driven harder and harder. The problem doesn’t seem to correlate to mileage, as many lower-mileage cars appear to have been affected as well (cars with less than 50,000miles on the odometer).

     To solve this problem, remove the lower oil pan and secure the nut in place so that it will not fall out. The one fail-safe trick to secure the nut is to tack weld it to the sprocket. Once welded, that nut is not going to come off under almost any circumstance. Other people have run safety wire through the nut, applied Loctite, and deformed the inner edge of the nut with a punch. If you don’t weld it, at least replace the nut with a new one (part number 11-41-1-735-137). Keep in mind that this nut is reverse threaded, so to remove it, you need to turn it clockwise.

Machine Shop 101

If you plan to have your engine rebuilt, or a top-end rebuild performed, you will probably need to take some of your parts to a machine shop. Some tasks require special, precise tools and knowledge that only a machine shop possesses. Most of the time, owners drop off their parts and then pick up magically rebuilt parts with no clue as to what really happened to them. This section aims to take some of the mystery out of what happens to your parts when you drop them off.

     Machine shops are especially useful for their parts cleaning services. For less than $100, the shop will clean and bead blast sheet metal, flywheels, heads, body parts--just about anything you want. If you’ve ever sat in your garage with a piece of sandpaper and a block of wood, you will instantly recognize how much time and energy can be saved by having your parts blasted. If, for some reason, you can’t use a blasting procedure (on engine cases or oil coolers, for example), most shops have advanced cleaning tanks that are similar to industrial-sized dishwashers for greasy, oil-soaked parts.

     Cylinder head reconditioning is a popular procedure performed at the machine shop. This job generally can’t be performed at home because the process requires too many specialized tools

     First, the valves and springs are separated from the head. The head is then placed into a specialized spring compressor tool that compressesthe valve spring, allowing for removal of the entire spring assembly. . The valves can then be removed from the assembly. Finally, the head is either cleaned or blasted until it looks like it just came out of a brand-new BMW box.

     The heads are then inspected to see if they need new valve guides. In most cases, the guides will be worn beyond the recommended BMW specifications and need to be replaced. To quickly see if a guide is worn, the valve is inserted into the guide to see if it can wobble it back and forth. If it doesn’t wobble, then a more precise small-bore gauge will be needed to accurately measure the guide.

     If the guide is worn, it needs to be removed. Threads are tapped into the guide and a cap screw is screwed in. This screw gives the valve guide puller a grip to remove the valve from the head.

     New guides are pressed into the head. Advances in valve guide technology have resulted in new materials with higher wear strengths. Newer guides may look different than the older ones and should last considerably longer. After the guides are pressed into the heads, they are reamed to ensure that the inner bore is within the proper specifications.

     The heads contain valve seats, which are steel inserts pressed within the aluminum casting of the head. In most cases, it is not necessary to replace the seat in the head. The seat is machined in precise alignment with the new valve guide. A machine that aligns itself with the new guide cuts the seat at a specific angle so that the valve will seat and seal properly.

     The valves themselves are machined as well to match the angles of the valve guides and valve seats. For a valve to be reused, it must still have a significant amount of material on both the outer edge and the valve stem itself. If not, the valve can no longer be used. In general, a valve can be used for one or two rebuilds before it will need to be replaced. Exhaust valves should only be used once, unless they are the more-expensive sodium-filled valves. The sodium-filled valves dissipate heat better than standard stainless-steel valves and thus are less vulnerable to the wear and tear of thermal shock that might affect a steel valve. In turn, the valves are set into a valve grinding tool and precisely ground to the angle that matches the angle on the valve seats.

     As you can imagine, the machining of the valve, guide, and seat are precision processes that need to be aligned together. If a machine shop is sloppy, or its equipment is out of alignment, you might be in for trouble later on. In some cases, the cheapest machine shop might not do a quality job. Unfortunately, it’s very difficult to check the tolerances on the valves after you get them back from the shop.

     While you’re there, also take your engine case in to be cleaned and checked. Be sure, however, that the case is not sandblasted, as sand may get caught in the tiny oil passages that feed various parts of the engine. The shop will check the engine case to ensure all the bearing surfaces are round and aligned with each other. If they are not, a procedure called “align boring” is performed. In many cases, machine shops will outsource align boring, because the necessary machines can be large and expensive. Align boring increases the outer diameter of the bearings to a specific size, while aligning all the bearing surfaces within the case. After the case is bored out, you must use oversized bearing sets instead of the standard sets.

     Also take the crankshaft to the machine shop before using it in a rebuild. Magnafluxing is a common procedure associated with crankshaft inspection. This process exposes all the flaws in the crankshaft, affording detection of any microscopic cracks on the surface. Have your crankshaft Magnafluxed if you plan to reuse it.

     Magnafluxing is a relatively simple process. The crankshaft is initially magnetized using a large circular magnet. The magnetic field is applied to the crankshaft at a 45-degree angle, so the process will detect cracks that run both parallel and perpendicular to the length of the crankshaft. The crankshaft is sprayed with a special liquid that has a magnetic powder suspended within the solution. This powder becomes trapped in any cracks present in the crankshaft. The crankshaft is then examined under an ultraviolet (black) light in total darkness. Under the black light, the cracks clearly show as bright lines in the surface. Crankshafts typically show failures at the points where the journal bearing meets a center flange.

     After the crankshaft is tested, it is demagnetized and then washed in solvent to remove the Magnaflux material. Make sure the crankshaft is demagnetized; otherwise, the tiny bits of metal that inevitably find their way into your engine oil will stick to the crankshaft bearing journals.

     It’s also wise to get the crank polished. The bearing surfaces of the crank require a smooth surface in order to properly create a thin oil film to ride upon. If the surface is at all rough, it disrupts the flow of oil around the bearing. Polishing the crank keeps the oil flowing smoothly around the bearing surfaces and increases engine bearing life.

     Additionally, the connecting rods need to be reconditioned at the machine shop. New wrist pin bushings should be placed at the rod’s end. The procedure known as “resizing” ensures the size of the rod bearing that fits around the crankshaft is correct. Over the life of the engine, rods sometimes stretch, causing the rod bearing surface to become slightly out of round. In order to correct this problem, the rod cap is removed and a small amount of material is removed from the mating surface. The rod cap is then reattached to the rod, and the bearing surface is machined to original factory specifications. Removing a small amount of material from the smaller rod half is common and doesn’t affect the strength or reliability of the rod.

     Finally, it may be necessary to have your camshaft reground. Although most BMW engines don’t exhibit large amounts of wear on the camshafts, some engines may require a regrind and polish close to original specifications. If the camshaft is at all pitted, it may be necessary to weld the pits, regrind the shaft, and retreat the metal to reharden the surface on the lobes of the cam.

     Entrusting any or all of these tasks to a reputable machine shop will help ensure a long life for your engine.

BMW Spark Plug

One basic tune-up procedure for just about any car on the road is the replacement of your spark plugs and spark plug wires (where applicable). On the BMW E36 six-cylinder engines, BMW has eliminated the use of spark plug wires by integrating six small spark plug coils that sit on top of each spark plug. While this configuration may be a bit more expensive than the typical single coil, single capacitive discharge box configuration, it makes the car's ignition system more reliable by removing a component that constantly wears out and fails (spark plug wires). It's a pretty cool setup, not commonly found on older cars. As manufacturing components has become increasingly inexpensive, ignition setups like these have become more common.

I recommend replacing your spark plugs every 10,000 miles, or about once a year. In reality, you can probably go longer than that, however, you never really quite know how long the plugs are going to last, or you may forget to do it if you don't setup a yearly schedule. Needless to say, replacing your spark plugs is one of the easiest tasks to do on your BMW - provided you have the proper information, which I will provide here.

Begin by prepping the car. The only thing that you really need to do is to make sure that the car is cold. If you try to remove or install spark plugs in a hot car, then you may encounter problems with the spark plugs gumming up or damaging the relatively delicate threads in the aluminum cylinder head. Just make sure that the car is cold, or at the bare minimum, only slightly warm to the touch.

Let's talk about the six cylinder cars first. The first step is to remove the top plastic covers from the engine. These serve no mechanical purpose - they are there only for decoration and to prevent dust and debris from getting into the recesses of the engine. On the six cylinder cars, there are two covers, a long thin one on the top of the car, and a wider one towards the left. Speaking of left, for the purpose of this particular tech article, I will refer to the left side of the engine as being on the left as you are standing in front of the car looking at the engine. The right side would, of course, be opposite to that. For reference, the windshield washer bottle would then be on the left, and the air filter would be on the right.

On the two plastic covers, there will be two small, snap-in plugs on the top. Carefully remove these plugs (don't drop them into the engine) with a small screwdriver, prying them up as you grab them (Figure 1). Underneath you will find a nut that holds the cover onto the top of the engine (Figure 2). Remove the four nuts on these two covers, and they should both simply slide up out of the way. Figure 3 shows the engine with the center cover removed.

Underneath the left cover, you will see the six spark plug coils that sit on top of each of the plugs (Figure 4). You need to remove each of these carefully, in order to gain access to the plugs. Using a screwdriver, release each connector from each coil. There is a metal retaining ring on the rear of each one that fastens it to the coil (Figure 5). Once you lift up on the retaining clip, then the connector should simply slide out of the coil. Carefully remove all of the connectors from each coil (Figure 6), taking care not to bend the wire harness too much. These wires are stiff, and generally don't take well to being bent in multiple directions. Just be gentle with them.

To assist with your maneuvering of the wires, detach the center clip that holds the wires that come from the center channel. This clip is shown inFigure 7. Gently place the wires off to the side and out of the way, without bending them terribly.

With the wires detached and placed slightly out of the way, you can now remove each of the six coils. Each coil is fastened to the valve cover using two screws. On two of the coils, there are two small ground straps that connect the coil to the stud on the cylinder head. Take note of these ground straps - they must be installed properly when you are finished, otherwise your car may encounter problems. These two ground straps are shown marked by the greens arrow in Figure 8 and Figure 9 (coil already removed in this photo).

Remove each of the two nuts that hold each coil to the valve cover. At this point, the coil should be able to be easily pulled right off of the engine (Figure 10). The coil has a small coil pack on one end, and a spring-loaded spark plug connector on the opposite end. Simply remove the coil/plug assembly and place it off to the side. All of the coils are the same, so it doesn't matter which cylinder bank it came off of - unless you are specifically trying to troubleshoot a bad coil fault code that was displayed by the main computer.

With the coil removed, you should be able to look down the hole and see the spark plug hiding in there. Figure 11 shows what the top of a normal looking spark plug looks like. However, as you remove the plugs, you may discover something peculiar. The way that the ignition system is designed on these BMWs, there is the opportunity for the spark plug holes to completely fill up with oil, if you have a leaky seal on your valve cover. When you pull out the spark plug connector / coil combo, you may find that it is completely submerged in engine oil, as shown in Figure 12 and Figure 13. Looking down the hole, you may not even be able to see the spark plug because the entire hole is filled up with oil (Figure 14 and Figure 15). While common sense says that this is not a good thing, the reality is that this is actually quite common, and doesn't seem to affect the performance of the car one bit. If you do find this oil in your spark plug holes, I would suggest that you go one step further and replace the valve cover gasket. This replacement procedure is very simple, once you have the coils removed, and should only take you about 20 minutes more, providing you have the actual gasket on hand. If you find oil in your spark plug holes, then you should definitely replace the gasket.

If you find that you have oil in your spark plug holes, I suggest that you take some paper towels and attempt to soak up as much of the oil as possible, before removing the spark plug. If you don't get rid of the excess oil, then it will leak into the cylinder head through the spark plug hole when you remove the spark plug. This will cause your car to run sooty when you first start it up, and it may even foul your brand new spark plugs that you just installed!

Spark plug removal is easy - you just need the right spark plug wrench. I have one that I love - it's a spark plug socket with a rubber insert that catches the plug. In addition, it has a built-in swivel on the attachment end. This is especially useful when trying to remove plugs in hard-to-reach places, as they are always located on Porsche engines (BMW engines aren't really that bad with respect to spark plug access).

Using a breaker bar, grip the plug and turn it counter-clockwise until it is loose. Then pull out your tool and grab the plug. When the plug comes out, you may want to take a close look at it. The spark plug is really the best way to visually ‘see’ what is going on inside your combustion chamber. You need to pull out all of the spark plugs to replace them, so you might as well take a close look at them while they’re out. While today’s modern fuels make plug-reading much more difficult, you can still glean a lot of information from looking at them. A good, well-balanced engine will produce a plug that is light brown in color, and dry. If the engine is running too rich, the plug will often be coated with a lot of extra carbon. Keep in mind that the rest of your combustion chamber probably looks the same. An engine running too lean will have a powdery white coating on it, and the outer porcelain ring may have a burned appearance.

When reading spark plugs, pay close attention to the white porcelain ring around the plug. This white area will give you an excellent background to inspect the color of the plug, and to help determine how your combustion chamber looks inside.

If the plug is wet with oil, then that indicates that there is significant leakage into the combustion chamber past either the valve guides or the piston rings. This is generally a bad sign, and an indicator that a future compression test may not yield good results.

Figure 16 shows an unusual spark plug with all four of its electrode eaten away. I would hazard a guess that this plug was improperly plated from the factory, and as it progressed through it's life, the repeated sparking slowly ate away at the electrodes until they were gone. A plug in this condition would misfire often (if at all), and would generate poor performance for this particular cylinder. Surprisingly enough, none of the rest of the spark plugs in this set exhibited this type of damage. This is what leads me to believe it was defective from the manufacturer.

Figure 17 shows a brand new Bosch Platinum spark plug. While I don't have any specific preference for any specific manufacturer of plug, you should definitely make sure to get the proper ones for your car. Spark plugs have varied over the years as engines have been changed slightly due to smog regulations. The important thing to remember is to get the proper ones for your car (they are scaled by electrode type and also by heat range), otherwise you may encounter odd ignition problems. Spark plugs are cheap - I would go with a brand name like Bosch or NGK, choosing to avoid the no-name brands. Make sure that you measure the spark plug gap (if single electrode) with a spark plug gap tool before you install the plugs.

Install your new plugs using a torque wrench to measure the amount of torque applied to the plug (Figure 18). This is very important, as it is easy to over or under-tighten spark plugs. Make sure that the plug is firmly seated in your spark plug socket as it is very easy to insert the plug into the head and have it cross-thread. This means that the threads of the spark plug don't mesh properly with the ones in the head, instead choosing to "cut their own path." This damages the threads on the head, and in extreme cases, may destroy the threads in the cylinder head entirely. Trust me - you do not want this to happen. Proceed carefully and cautiously here.

Install each plug into the cylinder heads without using any anti-seize compound. Torque the spark plugs to 25 Nm (18.4 ft-lbs). While writing "How to Rebuild and Modify Porsche 911 Engines", I discovered that Porsche doesn’t recommend the use of anti-seize compound, as detailed in Porsche Technical Bulletin 9102, Group 2, identifier 2870. The bulletin applies retroactively to all Porsche models and the theory is that the anti-seize tends to act as an electrical insulator between the plug and the cylinder head. This could have detrimental effect on the firing of the spark due to the loss of a good, consistent ground connection. Keeping those findings in mind, I would make the same recommendations for the BMW cars.

With the new plugs installed (Figure 19) and properly torqued, you can replace the coils (don't forget the small ground straps shown in Figure 8 andFigure 9) and reattach the coil connectors (Figure 20 and Figure 21). Snap the wires back into their center holders (Figure 7) and replace the top two plastic covers. When you're done, your engine should look back to normal (Figure 22)

Changing plugs on the 318 4-cylinder cars is a bit different and a bit easier. You remove the spark plug cover in a similar manner (Figure 23). There should be a handy little blue spark plug wire pull tool under the cover. Use it to remove the plug wires from the ends of the spark plugs (Figure 24). With the wires disconnected, remove and reinstall the plugs in a similar manner to how I described the procedure for the six cylinder cars. You will also want to replace the spark plug wires every 30,000 miles or if they look cracked and worn out.

Index Page

Thursday 26 December 2013