E34 540i/6 Running rough

[JoeMadoo]

Hello, I've got a new issue with my e34 and have been searching for a while with no luck. I've had the car for 2 and a half years and haven't had an issue like this before.

Its a 95 540i/6 with 190k miles, D.Sylvia chip and magnaflow/resonator delete.

I took a 90 mile trip on the freeway to LA a few weeks ago, but did not make it. Luckily a friend of mine lives on the way. When I was accelerating on the on ramp, I noticed my car had a minor stumble, and about every 10 seconds or so after that it would stumble. Nothing major, just as if one cylinder misfires once. As I continued driving, I noticed it was starting to happen more frequently, and it would happen in just about any throttle position. I began to worry a little and drove the rest of the way in the slow lane.

As I got close to my buddys house (30 miles form LA, it was stumbling quite frequently, and I could only drive it decently in light throttle. Felt like I was running on 7 cylinders. It pretty much ruined my evening as I WAS going to the LA auto show :( The next day I had my car towed back home.

It idles rough and at about 500 rpms. I haven't investigated it fully, but there seem to be no coolant or oil leaks, and no exhaust smoke. The engine is still very r3v happy, but again it seems like 6 or 7 cylinders. If I hold the rpms at around 1500, it feels pretty smooth, but will burble here and there.

Possibilities that seem relevant to me: a bad coil, bad fuel injector or loose connections, a failing fuel pump or clogged fuel filter, a hidden vacuum leak (have replaced a few gaskets already), failing MAF, failing o2 sensor?

Thanks for reading my rant. Just looking for ideas or suggestions on what to investigate first. I am going to start with the fuel filters.

[BarryM6]

Go to www. E38 . Org

[JoeMadoo]

Look like they've got a lot of good info there. I'm going to try the things on this page.

Just curious if anyone has had similar problems like this in the past and what they did to solve them.

[JoeMadoo]

Anyone have any advice?

[bkbimmer]

Anyone have any advice?

Buy my M5, it runs great :) Other than that, I got noth'n.

[xxx-Lost-Soul-xxx]

My mom has the same ride, When the Plugs went on it, It would do what you described.
Also are you sure the Valve covers arent leaking? Ive heard of when the oil seeps in it would have a slight miss.

[JoeMadoo]

Buy my M5, it runs great Other than that, I got noth'n.

Maybe. I'm in love with the v8/6 speed combo though, especially when it runs.

My mom has the same ride, When the Plugs went on it, It would do what you described.
Also are you sure the Valve covers arent leaking? Ive heard of when the oil seeps in it would have a slight miss.

Thanks for the info. I changed my plugs a few months ago when I got her smogged. I don't think my valve covers are leaking but I will check it out when I take the drivers side cover off. I think my issue might be worse than I though.

Once I took the cover over the coils off, it revealed a fairly loud knocking or tapping sound as shown in the video. I might need some head work.

[xxx-Lost-Soul-xxx]

Are you sure ALL the coils are Making contact?

Im moving to Palm springs and I have Friends in Pomona.so maybe sometime i can see this car,and lend a hand.

[JoeMadoo]

That would be great. My car is in Victorville right now. The coils seem to be fine from what I can tell. I think it's strange that it slowly got worse and worse over the course of about 2 hours of driving.

[ToPLeSS(e30)FeinD]

i had/have a similar problem with my 540i/6. turned out to be bad O2's.. i say "had/have" because i havent gotten around to replacing them but unplugging them solved my issue (for the most part). try and see if the engine temp has any effect on the symptoms.. besides that the only thing i can say is either try compression test or start unplugging sensors and see what happens..

another thing a buddy of mine pointed out was that the boots between the coil and the spark plug will create a misfire if there is a microscopic crack. after the rubber heats up, the spark grounds to the head rather then through the plug. easy solution, just find a 740 at the yard and pocket a batch, see if it makes a difference..

hope any of this helped. let me know if i can help with anything else.

[JoeMadoo]

Thanks for the reply Topless. At first I was thinking it could maybe be the o2 sensors, coils, or plugs, collant temp sensor, etc. But the fact that it has such a pronounced tapping/knocking coming from the head makes me want to rip the head apart. Maybe I'll pocket a drivers side head from the junkyard today.

[ToPLeSS(e30)FeinD]

Haha. Pockets ain't deep enough. Good luck man. Let us know what it turns out to be.

[straight6pwr]

had a running rough/car dying/suspected intake leak or o2 sensor or whatnot and it ended up just being a partially plugged fuel pressure regulator. car would only throw a code when it was stumbling REALLY bad and then would die. my mech was able to diagnose the low fuel pressure with his tools after I found that the MAF was fine and there were no intake leaks.

[ToPLeSS(e30)FeinD]

Nice! I'll put that on the list if I have any other problems.

[e34_spangler]

yo id try putting premium in your car cause i let my old man drive my car for a while and he put regular in for a while got that same noise then i put premium back in the noise went away fast!