Just bought a 95 M3. Decided to degrease the engine bay as it was pretty dirty near strut towers. I was careful as to how much i was blasting water around in there, and wiped the engine bay down with a towel afterwards. Car was fine for a few hours. Next time I started it, there was a mis fire and was runing on 5 cylinders. I ran into this before on a previous car, and just un hooking the battery fixed the problem. So i tried it. It worked, until the next time i started the car. The only exposed wiring on the car is the MAF wiring, and i dis connected the plug and it was dry. no moisture. the top of the engine is covered by the M power plastic cover, so i dont think that any water could have gotten down into the plugs.
Anyone have any ideas as to where to look next? Im unfamiliar with BMW’s as this is my first one. I need to figure this out cause the car drives like shit.
Also… the car was perfectly fine when i started it this morning, and worked great until it hit full temp. When i reached temp about halfway to work, the mis came back.
If any of you are an experienced bmw tech or have an idea how to fix it… I pay great… lots of beer, pizza, and even a little cash for your help.
get access to something that will talk to it to retrieve the missfire code, record what cylinder it is, swap coils around (documenting which one is which, and where they went) see if the missfire follows the coil after getting the missfire back and replace the coil if the missfire follwed it. they go pretty often.
If there’s no code you won’t know where the miss is.
Take off the engine cover and check for water on the coil packs. The metal bracket they bolt to is used as their ground, there’s a potential water or degreaser caused a little bit of rust or something to make a bad connection.
I’d also check all the wires and connections. Give them a spray with WD-40.
If you do nail it down to a specific coil pack, buy the actual OEM Bosch one. I just changed one in mine this summer. It’s only a few dollars more than the cheap generic one.