e39 Fluctuating Idle,black smoke and loss of power. HELP!

My recently bought e39 540i sport 98' with about 150 thousand miles is acting up!

On cold start the idle fluctuates form about 500 to over 1000 rpm. It jumps up and down but the longer it idles the better it starts to get. After about 5-7 min it evens out and seems to be normal again.

The engine also shakes a bit when and there is black smoke coming out of the exhaust!

When pushing down on the gas while in drive it sometimes loses power for a sec then jerks and accelerates rapidly.

The check engine comes on and off but i will post codes later. (possibly tmrw?)

ANYTHING HELPS! THANKS>

so no one has any idea what this might be?

Have you cleaned your ICV lately? That could fix your idle issue if it's gummed up.... very easy job.
Black smoke sounds like burning oil, which most commonly seems to be the CCV, or rear manifold cover (on the rear of the intake manifold, the black box thing with a few hoses coming out of it). Lots of DIY links on replacing this, and I think it's $200-$300 part.
First, you need to scan and report back with codes. The codes will tell you what is happening to cause the CEL so before replacing any parts make sure you get the codes.
hope this helps.

^ i didnt know that the rear manifold cover gasket might cos black smoke.. well need to check up on that in my car too.


i would suggest you taking off your intake manifold, replace all the gaskets, clean it, and see what happens.

Originally Posted by theroosh686

so no one has any idea what this might be?

Hmmm... I once googled for someone "white smoke BMW E39" and found these threads which I put into the VERY best of E39 Links to help others:
- Diagnosis of white smoke out of your exhaust pipe (0) (1) (2) (3) (4) (5) (6) (7) (8)

Some of those threads, IIRC, also cover "any smoke" coming out of the tailpipe ... but ... what I recommend ... (since I haven't done it myself) is for you to google for "black smoke BMW E39" and then list for us the threads you find most applicable.

Then, given those best-links, we can put them in the VERY best of E39 Links so that others benefit from the effort (as is always our mantra).

Let us know what links help you out best!

Good luck. Sorry I can't help more.

Originally Posted by theroosh686

On cold start the idle fluctuates form about 500 to over 1000 rpm.

Well, in the VERY best of E39 Links we have the following diagnostic trees which may be of help to you ...

- How to diagnose a BMW E39 engine misfire (1) & a cold-engine intermittent misfire (1)

Originally Posted by theroosh686

so no one has any idea what this might be?

You need to post the codes. Otherwise we are just guessing.

Thnks. and yes codes coming soon.

UPDATE!
so i got my codes ran at autozone and this is what i got.

p0300-?
p0305- misfire cylinder 5
p0304- misfire cylinder 4
p0100-?
p0111-?
p1585-?

( the codes with the ?= the guy at auto zone gave explanations for all but i noticed he only ran two of the codes under bmw, the others were explanations and probable causes for other oem brands like Volkswagen and "domestic". He did say they were going to be close explanations but i just dont trust him so i wanna find out exactly what the codes mean bmw wise.) makes scene? ^

I also found a couple leaks in my air intake pipe and a few hoses were leaking air,fixed and replaced. all right next to the maf leading to the icv . also cleaned icv. and now NO MORE BLACK SMOKE OR WEIRD FLUCTUATING IDLE!!!!!! Codes still remain.

the car idles at about 1100-1200 rpms now. is this high? how do i turn in down. pictures please!!!!!!!!!!!!!!!!!!!!!!!!! where is it located.

thnks to all, earlier replies helped me alot! sorry for the bmw lingo, im a nube when it comes to explaining things.