BMW Ignition Coil Problems

BMW Ignition Coil Problems

When I first started as a BMW tech, there were pretty much two engines out there in practically every car, except the M cars, of course. There was the N62 and the M54. So many cars with the same engines. This is how we get so good at fixing them. It's the same problems in most of the cars so we know what to look for and what we need to do to fix it. Anyway, one of the big problems that these M54 engines had was the ignition coils. They used to fail all the time, and at one point BMW had a huge recall (about 500k cars) to replace all the coils on the 6 cylinder engines. If they weren't replaced they would swell up, short out internally and damage the DME (engine computer).

               

Here are two views of a typical BMW ignition coil. This is what makes the spark plugs fire. There are not spark plug wires. The DME controls these directly, and since each spark plug gets a whole coil all to itself, it can fire the spark plugs more effectively.

The only bad thing is that more than a decade later, these are still going bad all the time. The N51, N52, N52TU (basically the same engine) all use these coils, and for some reason they fail. Now for some very weird reason, the same coil in an N54 or N63 does not fail. Maybe because of the increased torque, somehow it causes less stress on them. One thing's for sure, when they go bad you'll feel it. They can fail completely, in which case the engine will feel like it's hopping inside the engine bay. Or they can fail under a load, which means when you're doing hard acceleration or trying to accelerate at a high speed (45-50 mph) on top gear. At this point you'll feel the engine feel like it's intermittently bumping/ stopping for a split second.

To make a long story short, these coils fail so much that BMW recently published a service bulletin saying that under certain circumstances, if a car comes in with a bad coil, we now need to replace all 6 coils, not just the one that failed, with an improved coil made by delphi. They are very easy to replace, by the way.

BMW N63 Valve Stem Seals

BMW N63 Valve Stem Seals

I remember back in the day, probably around 2008, when this guy came in with an E53 X5 with an N62 engine complaining about smoke from the tail pipe. We had never seen this before, so we checked the car the first time and couldn't find anything wrong with it so we let the car go. The guy came back a week later, insisting that his car was smoking from the tail pipe, and told us to let it idle for 15 minutes. We did that, and sure enough, there was smoke coming from the tail pipes. After checking a lot of stuff like crankcase vent valves and  valve covers we figured out that the valve stem seals were leaking. After that, we started seeing a lot of these engines smoking from the exhaust at around 75,000 miles and up. Some were not too bad, and some looked like mosquito trucks.

After so many years of seeing these seals leak, the new N63 engine came out. BMW never addressed the issue with the N62, but we figured that for the new N63 engine there would be a design change to improve this flaw. Well guess what, the N63 uses the same damn part number for the valve stem seals in both engines and now the N63 is smoking too. When you have smoke from the tail pipe from worn valve stem seals, this means that you're burning the engine oil inside the combustion chamber. All engines consume some oil, but these burn a LOT of oil when they are smoking, and you end up topping off the engine oil frequently. BMW now states that it's normal for these turbo engines to consume about a liter of oil every 750 miles. In my opinion that's really high, but then again I'm not an engineer. I just haven't seen a properly running N63 burn that much oil. It also doesn't help that the turbos sometimes start to leak and can also cause a lot of oil burning, or make the situation worse combined with the valve stem seals. BMW finally caught on and decided to address the situation. They designed an improved valve stem seal, which is now green in color, instead of the old orange/red ones. Hopefully these will last longer. They also have a newer way to replace the seals without having to remove the engine or the cylinder heads from the vehicle. I got one of these smoking N63 engines a few months ago, so I decided to take some pictures to share the repair here.

I had to check to make sure that the seals were really leaking, so I removed the turbos and the exhaust manifolds to inspect the valves.

N63 with turbos and exhaust manifolds removed

This is what I found:

         

On the left picture you can see the oil had passed through the seals and had entered the intake port. The right picture is of the intake manifold. The oil had been collecting there and also on the intake valves and ports of the cylinder head. After this was confirmed I proceeded with the repair.

On the newer F series platform (F01, F02, F10, F06, F07) the engine is usually not removed from the top. It is lowered, with the transmission and front sub frame on a hydraulic table. The drive shaft, power steering, coolant hoses, fuel lines, etc. are disconnected from the engine and transmission. Then the table is placed under the car and is jacked up. The sub frame and transmission bolts are removed and the complete engine, trans and front sub frame are lowered from the chassis.The vehicle stays up on the lift.

N63 engine on hydraulic table

After this, the real fun begins. There is a newer way to do this job, which consists of taking the camshafts off and replacing the valve stem seals with the engine and cylinder heads in the car, but when I did this one, the tools to do it this way did not exist, and I had to do it the old way, which is to remove the cylinder heads and place them on a special jig, and then remove the camshafts, lifters, valve springs and finally replace the damn valve stem seals. It sounds like a lot of work because IT IS a lot of work.



 

     On the top picture, we have the bank 2 cylinder head with cover, injectors and high pressure pump. on the bottom picture, the same cylinder head with the valve cover off. Camshafts and vanos units are still installed.

Same cylinder head on the top picture with vanos and camshafts removed. Bottom picture shows part of the engine block after removing the bank 2 cylinder head.

Close-up picture of one of the cylinders and piston.

After the cylinder head is removed, I also removed the fuel injectors so I could place it on the cylinder head jig to remove the valve springs and seals.

Once the cylinder head is mounted here, the valves are held in place from underneath so the valve spring can be pushed down, and the keepers can be removed. Then the spring can come out to access the valve stem seal.

The spring is compressed by the special tool, exposing the keepers for removal.

This is a picture of the original (red) valve stem seal.



This is a picture of the improved (green) valve stem seal.

Comparison of the old vs new seal. You can clearly tell the old one on top is wider and bowed out compared to the new one on the bottom. 

  

Old seal on left vs new seal on right installed on valve.

After all the dis assembly, I finally get to the valve stem seals. You can see the old one (reddish color) is mushroomed out, causing it to leak and let the oil go through. The new (green) seal fits much tighter around the valve stem, creating a better seal.

Also, since the seals had been leaking for a while, the intake ports and valves were full of carbon so I took the opportunity to clean these to increase airflow.

Valve springs on the back of the pictures. The valves on the left side of the picture are the ones I had already cleaned, compared to the dirty ones on the right.

After cleaning all the valves and ports and replacing the valve stem seals I re assembled the engine and reinstalled it in the car. It ran great after the repairs.

Stalling E90 M3

S65 engine without intake manifold

Today was one of those days that I was really exited to work on a car. It was an 2011 M3 that intermittently stalls. Another tech scanned it and there were no faults, so they did the usual procedure, which is to reprogram the car with the latest software…the magical fix for everything. Only that this time, when the guy who takes the cars on extended test drives for cases like this drove the vehicle, the engine died twice on him. Sooo, I guess that means it wasn’t the software, huh.

The next step was to ship the car over to me for diagnosis. Curiously enough, another 2011 M3 with intermittent stalling came in the next day, also with no faults stored. Fun times! After a lot of thinking what the fuck could be happening with this thing and theorizing and talking to my team mates on what could be intermittently causing this shit to happen, I decided the best way to go was to chase whatever controls the idle air system. I looked at the training manual and found there is one common controlling device for the idle on both banks, so this would make the most sense, then I noticed the tank vent valve vents into the idle air valve. If the valve stays stuck and vents when its not supposed to, it could cause erratic idling. There are so many things that could be causing this, and the more you think about it, the crazier stuff you can come up with. This is when I need to remember to KISS (keep it simples, stupid) and try the easy stuff first.

So I went ahead and replaced the idle valve and tank vent valve, and so far I haven't heard anything again from the car. It was worth attempting to do the repair after analyzing what may have been going ok. There are many people out there that have the same thing happening to them on the s65 and s85 engines.  I would definitely recommend starting with the idle valve/ purge valves. The s85 has two of each. It's expensive, but if you have these cars you need to be able to pay to play.

Throttle valves, throttle actuators and idle air valve piping

Idle air valve and piping that goes under throttle valves.

Diesel Power = Torn Harmonic Balancer

On the left is the original harmonic balancer. On the right is the redesigned one

BMW used to have diesel engines in the USA, until stringent emission laws prevented them from bringing them here anymore. They continued to have them in different parts of the world, and after a lot of work to meet emission regulations, they managed to bring the 6 cylinder diesel engine back to the USA in the E90 and the E70, and let me tell you, they are really powerful. They have so much torque that we've seen a few of the E90s break the harmonic balancer (the big pulley in front of the crankshaft that is used to drive the belt and accessories). When this happens the engine runs but you have no power steering, A/C or alternator to charge the battery. Also, you can smell rubber burning pretty bad. Luckily I've only seen a few of them, and apparently the problem has been corrected by a re designed, beefier harmonic balancer. Now people can enjoy the gobs of low end torque without worrying.....at least about THIS issue. BMW has learned a lot about diesel engines in the USA now and have made drastic improvements on the newer diesels and have now released the 4 cylinder diesels in the USA too. More to come on diesel repairs soon!

You can see on the old style how the rubber is ripped around the center hub. The hub will spin, but not the rest of the balancer.

New balancer has a lot more rubber to prevent reoccurrence of the issue.

N54 Engine Air Leak

Valve cover, near the oil filler cap

Engines today have a very complex system to manage what goes inside them, as far as air and gas goes. They have various sensors that the engine computer (DME) use to regulate how much gas the injectors are going to inject into the cylinders depending on how much air is going into the cylinders. The DME is smart enough to make adjustments if the mixture is a little off, but if the mixture is off too much, then the engine is gonna run like crap. This is the valve cover of an N54 engine (the plastic cover that sits on top of the engine). We've seen a few of these engines that come in running bad, with lean mixture faults (there's too much air going into the engine, so the DME can't keep up with the amount of gas that is needed for the engine to run right). When we do a smoke test we've found a common spot on these engines that are leaking air. The valve cover cracks at this specific spot. It's easy to spot, and it's the first place to look when you have these faults.

Can you spot the crack?

It's right next to that fuel injector line. That slight crack causes havoc.

BMW N63 Customer Care Package

BMW N63 Customer Care Package

N63 engine on E70 X5

N63 without cover

Many of you might be wondering what exactly is the N63 customer care package, and why this is being done. First of all, this is not a recall. I don’t think any of the components being replaced would leave anyone stranded if they fail. I believe BMW is doing this to improve the engine’s reliability and customer’s experience and expectations. As part of the customer care package, the fuel injectors, vacuum pump, and low pressure fuel sensor are checked to see if they have already been replaced with an improved part. If it has, then there is no need to replace them again. If they have not been replaced with the improved parts, they will get replaced. Besides these parts, all engines get new mass airflow sensors (I have never seen one fail), crankcase vent pipes (the plastic would crack all the time, but they were redesigned to withstand more heat), and seals for the intake pipe going into the turbo charger(they get hard as a rock and don’t seal right, but the material was redesigned). The second part of the customer care package is to check the timing chain for excessive wear through a test plan that actuates the vanos units to their limit positions and checks if the limits are too far off, indicating that the chain has stretched. I think only about 5-10% of engines need the timing chain done. Besides this, the second part of the CCP requires an engine oil change and programming to reduce the oil service interval to one year or 10,000 miles.

As BMW’s new reverse flow twin turbo V8, there are some problems that are going to arise, as is the case with any new design. When the twin turbo n54 came out, it had horrible problems with the high pressure fuel pumps, low pressure fuel sensors and high pressure fuel injectors. Well, the same fuel injectors and low fuel pressure sensors are used in the N63 engine, plus the reverse flow cylinder head design causes the injectors to be exposed to higher temperatures, which causes them to fail. Some of the early N63 injectors were failing so badly that they would fill the cylinders up with fuel, causing the engine to hydro lock. In all the time that these engines have been out, I have yet to see one of these come into the shop. It’s not as frequent as some people make it out to be. Usually the engines would run rough and misfire, the check engine light would come on and the cars would come to the dealer, and we would end up replacing all the injectors. In 2013 the injectors were redesign to withstand more heat, and after the original injectors were replaced with the improved new ones, we would rarely see them fail again. The low pressure sensors do go bad frequently, but you can’t even tell the difference in how the engine runs, and most of the time it wont even set the check engine light. The sensor has been redesigned also, so now they don’t fail as often.

OK injector on the left, fouled injector on the right.

Overall I think BMW did a great job in stepping up to the plate and taking care of their customers and hopefully this will improve the company’s reputation in terms of reliability. All engines, not matter what company designs it, are going to have issues. The more technologically advanced an engine is, the more difficult it is to make it reliable, yet BMW engineers always find a way to make it happen. The N63TU is more advanced, powerful and reliable than the N63. The same goes for the N55 compared to the N54 (in my opinion). So if you have a BMW with an N63, get the CCP done and go enjoy your ultimate driving machine.

BMW Z4 E89 PT CAN Bus Issues

Wiring rubbing on sharp edge of DSC unit block near top center of picture

Today I got all happy because when I asked my team leader for work, he told me he had another difficult car. They had scanned it earlier and found about 100 CAN bus related communication faults. Most techs hate this kind of problem because it's really hard to fix. A CAN bus is how some of the control units in a car talk to each other and share information. For example, the DSC control unit will take the signal from the wheel speed sensors and send it over the CAN bus to the transmission so it know what gear to be in, and will also send the information to the instrument cluster to display the vehicle speed in the speedometer. The bus itself is usually two intertwined wires that connect to a certain group of control units. There’s a PT CAN, which lets all the power train control units talk to each other, K CAN bus for the control units of the vehicle’s interior, and other buses for sub systems. It’s hard to find these communication issues because they are usually intermittent and everything is working fine when you go to check it. I was wondering what the hell to do with all the faults. I started looking at all of them and the amount of times they had happened. I found they were mostly related to the DSC control unit, which controls the stability and ABS of the car, among other things. I thought to start with the control unit itself, but I decided to inspect the big wiring connector in case there was anything stupid going on, or maybe mouse damage (when rats make nests inside the engine bay and chew through wires, causing problems). When I was looking at the connector I noticed the wiring harness was rubbing up against the sharp metal edge of the DSC unit. When I looked more closely I found it had cut through the harness and was slightly cutting through the PT CAN wire, causing it to short and mess up communication between the control units. I fixed it and cleared the faults. Drove the car and rechecked faults. Car was fixed. I couldn’t believe how lucky I was to have found that so quickly. It made me look like a bad ass.

After unplugging the wiring and inspecting closer, you can see the small cut through the harness in the middle

I cut the harness open to investigate further. The red/ blue wire with the small pin hole in the middle is the PT CAN wire that was slightly shorting.

BMW 3 Series F30 A/C Blower Motor Noise

BMW 3 Series F30 A/C Blower Motor Noise

We have been seeing these come in for years. The new F30 3 series, when you put the blower on high speed, makes a weird loud humming noise. Every time I check it out it turns out to be the same thing. There is a spot under the passenger side of the hood where the fresh air goes inside the car, and leaves accumulate there. Some of the leaves get sucked into the blower, causing the noise. BMW knows about this and came out with a special kit. It consists of a plastic grill that we put over the opening to prevent the leaves from going in there again. It's a very simple repair. Not too many things to disassemble, and is pretty effective too. I took the car apart until I got to the blower and sure enough there were a few leaves in there. I took the blower motor off and removed all the leaves and rechecked to make sure the noise was gone. That did the trick! Then to prevent it from happening again, I installed the grill and reassemble the car. Good to go! This has also happened to the F10 5 series and F01 7 series, but the repair is a little different. If I come across one I will post it.

This is the area under the hood, on the passenger side, where the leaves come in through.

After taking a few covers off you can see the hole where the leaves go in and turn out at the blower motor.

Same place. You can see the blower motor inside the hole. This is one of the little leaves that was causing the noise.

This is the same area after installing the grill to prevent this from happening again.

BMW F10 Gas Leak

The other day I got an F10 with a gas leak in the shop. The customer was complaining about a pretty bad gas leak. Sure enough, after having the car idle in my bay for about 5 minutes, there was a pool of gas by the right rear tire. I raised the car and inspected the gas tank, just in case they somehow hit something down the road and had broken it, but it looked like the leak was coming from higher up in the gas tank. I took the seat out and checked the right fuel tank cover and found it was full of gas. at this point I thought the seal was leaking, but then I saw the real issue. The connector with the big power and ground wires had over heated, causing it to melt the plastic and make a hole on the top of the fuel tank cap.

In this picture you can see the connector wires melted, and the burnt pin exposing a hole on the fuel tank cap. This will also turn on the check engine light due to an evaporative emission system leak.

Here's a closer look at the hole on the pin at the gas tank connector.

Here's a closer look at the connector.

As for repairs, I had to replace the right fuel tank cap, which comes with the fuel pump, and I had to cut the wiring and replace the connector and the pins. Not a difficult repair. The worst part of the whole deal is having my face right above the gas tank with the lid off. After a while of smelling so much gas I get a little woozy. No biggie, though.