My 2000 540 keeps dropping coils - BMW Forum

garrard · 07-12-2011, 12:37 PM

Literally, within a week of having a coil replaced, the car will start missing in low gears and a few days later the "Service Engine Soon" light will come on. In a few cases, when the car is missing, it will flash at me.

Mechanic says I need to replace the third coil that has gone bad, but I am thinking there is something going on to cause the coils to fail. Each time it is a different coil and this time the coil is in the other bank.

He says he has never seen anything like this.

Have any of you? Any advice?

brettski · 07-13-2011, 08:37 AM

Welcome to the Werkz.

Does it miss when its sitting and idling?

Is you car an auto?

Are you sure that the coil packs are actually failing?

garrard · 07-13-2011, 08:45 AM

Yes - the coils are failing. The mechanic runs the diagnostics, gets the error, takes the coil that the computer says is failing, switches it out, then retests it to make sure the error follow the coil that was identified as failed. It is a 6 speed. Does not miss when idling.

brettski · 07-13-2011, 08:51 AM

Have the plugs recently been changed to a different brand etc?

Anything else been done to the car that preceeded this issue occuring?

How many miles has it done?

garrard · 07-13-2011, 08:56 AM

124,000. Just had all the plugs replace and all service was up to date as of late last summer. The first coil failed in November. Second one in June. And, less than a week later, the third. I sure hope I am not out there again next week replacing the fourth.

Mechanic says there were no other errors - voltage errors or anything that might contribute to causing coils to fail.

garrard · 07-13-2011, 08:58 AM

Oh, and he checks the plugs while he is diagnosing, too. Just to be sure.

brettski · 07-13-2011, 09:04 AM

I guess that these coils are all probably the original coil packs, made in the same batch and having done pretty much the same work in the same environment, they could theoretically fail at roughly the same time, but its unusual. Hang onto the old ones in case they turn out not to be bad. Have any of the new coil packs failed as yet?

garrard · 07-13-2011, 09:07 AM

Nope - no new ones, they are all fine. Yes, I guess I'm just "lucky" and they all were the original coil packs when this all started. They are Bremi but he says that they are not the type that were recalled - the ones where the boot and the coil were all one unit.

garrard · 07-13-2011, 09:09 AM

My mechanic's theory is just replace as they go bad. He says that dealerships will tell you when one goes they all have to be replaced - basically, just for their convenience. So that "non-mechanics" like myself are not complaining that they were just there for the same problem and why is it happening again?

garrard · 07-13-2011, 09:11 AM

I posted this just in case someone out there had experience the same thing and found an underlying other thing that was causing the coils to fail. But it doesn't see like that is the case. Also was wondering if someone had the same problem and just decided to replace them all and had results. I'm tired of driving out there! He isn't very close to home, but had to can my BMW mechanic of many years when ownership went to the kids and they were pulling shenanigans. Several of my friends caught them in out and out lies about what they did to the car, etc.

garrard · 07-13-2011, 09:32 AM

Brettski, thanks for your input. I like this site. I also have an ancient 525i (5-speed, 1991), so I will probably be here every now and then for advice.

brettski · 07-14-2011, 03:25 AM

If you can handle a socket and screwdriver these coil packs are easy to change, provided you know which one is faulty. It may be worth getting hold of a spare coil pack and change them your self.
Remove the engine cover
remove the two rocker cover blanks
remove the two screws on the rocker covers
undo the two nuts retaining the coil pack
release the spring clip that hold the lead to the coil pack
the coil pack then simply pulls straigh off the spark plug whilst sperating from the wiring
Reverse the process to reassemble.

garrard · 07-14-2011, 01:15 PM

That's the problem - is there any way to tell which one without the diagnostic equipment? Otherwise, my husband could easily do it - he used to work on Porches. Thanks for the instructions.

brettski · 07-14-2011, 04:42 PM

You could try disconnecting them one at a time to see if you can isolate the faulty pack.

Jack Dabsy · 07-15-2011, 02:41 PM

It must be the module that distributes power to the coil-packs...