M3 evo idle issue

[evobob]

On a cold start the revs would go upto around 1500- 2000rpm and bounce/ hunt for about a minute or two, then it settle with a slightly juddery idle... No problems on the road and performance wise just this issue..!

anyone any ideas? does this sound like a O2 sensor?

thanks..!

[MarkwG]

I hate to say "they're all like that", because a) I don't really know, so b) they might not be! But mine has done this pretty much since new, on & off, & it's no more than an occassional nuisance - tends to be after a shortish run, & I think it may be battery related - if that's fully charged, it's fine. I have found it's less prone to it, once it's had a good thrashing: which makes me think it's a useage issue, rather than a specific fault. I've had the diagnostics done, & nothing ever shows. Good excuse for a blast, as well

[thegreengoblet]

Check around the rubber coupling from the airbox to the engine. Mine started hunting when cold and it turned out to be a split in the said coupling.

[andye30m3]

could be an airleak between the airflow meter and the engine.

The gaskets between the throttle bodies and the head used to get to the age where they need replacing on the E30's so the E36's might be suffering now.

You can check for air leaks on the induction side by spaying wd40 around the gaskets / inlet pipe work when the car is ticking over, if there is an air leak the revs will pick up.

[andygtt]

andye30m3 said:

could be an airleak between the airflow meter and the engine.

The gaskets between the throttle bodies and the head used to get to the age where they need replacing on the E30's so the E36's might be suffering now.

You can check for air leaks on the induction side by spaying wd40 around the gaskets / inlet pipe work when the car is ticking over, if there is an air leak the revs will pick up.

strangelly mine has started slightly idling too high in last few months and I noticed a large split on the pipe from the airbox...

[racedriver]

2 options. The idle air control valve can get clogged up and not operate properly. 99% of the time if you remove it and clean with carb cleaner it should cure it.
Of it could be vacume hoses from air box. There is a plastic Y piece that can split.

[evobob]

racedriver said:

2 options. The idle air control valve can get clogged up and not operate properly. 99% of the time if you remove it and clean with carb cleaner it should cure it.
Of it could be vacume hoses from air box. There is a plastic Y piece that can split.

awesome.. does the Y piece come of the idle control valve..? will also check for air leaks..

MarkwG- your right mate..! its been fine last couple of days.. strange..!

[racedriver]

The Y piece is near or under the airbox and nothing to do with the idle control valve. It is awkward to remove the inlet manifold but it is the only sensible way to get to the valve.

[falkster]

andye30m3 said:

could be an airleak between the airflow meter and the engine.

The gaskets between the throttle bodies and the head used to get to the age where they need replacing on the E30's so the E36's might be suffering now.

You can check for air leaks on the induction side by spaying wd40 around the gaskets / inlet pipe work when the car is ticking over, if there is an air leak the revs will pick up.

Was just about to say that!

Not cheap to fix either.