e36 m3 intermittent dead misfire, need advice!

hi, my 99 m3 has this weird issue lately where it just will randomly have a really bad misfire when i start it up and it usually goes away after i drive it a little ways. its definitely on only 1 cylinder (code indicates only cylinder 4) and it doesnt happen very often. most days the car runs smooth as can be. but every now and then i will start it up and it will have that dead misfire on cylinder 4 and it feels really bad. already switched out the coil and the plugs look fine. and considering how intermittent it is, im starting to wonder about maybe a sticking valve? is that possible? or a problem with the injector? (maybe the o-ring or the pintle cap?) if anyone has any advice it would be greatly appreciated. otherwise im going to just start trying different things. thanks in advance for any advice!

Seafoam never hurt anybody. You might give that a try.


Funny how you've been a member since late 2009, but haven't posted until today. I would say welcome to the fest, but you've been here longer than me

hah, yea well i hadnt posted anything yet because i didnt have my car yet. my 1st car was a bimmer way back in 1999, and then i had a couple e30's a couple years ago, and now i just bought my e36 m3 last month. i love the car. estoril blue on dove. ill try to get some pics up soon.

Yay more m3's

ok so i just got another clue i think. along with my P0304 for the cylinder 4 misfire, i also have a P1250 which is a fuel pressure control fault. so now my thoughts are going to a possible leaky injector or maybe a cracked injector pintle cap or o-ring that is letting out fuel pressure and throwing that code. i hope to check out the injectors this weekend if i have time. ill post findings when i get them. thanks

Even though this is from the VERY best of E39 Links, it should still be applicable for the most part to the E36.

- How to identify all BMW computer-specific OBDII fault codes (1) & how to better understand the key EPA federal test procedure (FTP) concept of the BMW "drive cycle" (1) & how to diagnose a typical BMW E39 engine misfire (1) or a sporadic-temperature-change cold-engine intermittent misfire (1) obtaining the pending or diagnostic trouble code (DTC) using free or freeware scans (1) [except in California or Hawaii (1) (2)] or the cheapest ODII scanner in the world (1) (2) or a better overall scanner (1) or the best diagnostic tools (1) (2) (3)

Note that Seafoam is the LAST thing you do (when all else fails!).

I would try switching the number 4 injector with another. Clear the code, then see if it comes up on that cylinder.

It wouldn't be a bad idea to order injector o-rings and replace them while you're at it.

Good luck.

So you switched your coils and plugs and the problem stayed on the same cylinder? I'd look at the injectors if that were the case.