M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: Mannix on August 01, 2007, 10:03:04 PM
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So - I replaced my AFM with the reconditioned unit from Pelican. Revs right to the revlimiter now. That's great.
The only code left in the computer is 1222. So, I went on a hunt for vacuum leaks. I could not find any.
I sprayed carb cleaner all over the place, and got a change in idle when I sprayed the ICV/ISV/whatever it is called (Audi people {the 5cyl turboguys} call them ISVs, I-Stabilization-V).
So, I took it out and sprayed it out with carb cleaner. Seems OK. Put it back in, wound up creating a HUGE vac-leak under the intake. Got that back together, ziptied the hose onto the bottom of the ICV, just out of principle. No cracks in any hoses.
Symptom - slightly lumpy idle which eventually results in a CEL (1222), but if I rev the gas a tiny bit, the CEL goes off.
While the car is idling, there SOUNDS like there's a vac-leak down by the ICV. I can't feel it. I can smooth the idle out with carb cleaner. No cracks in the hoses in that corner. Hoses are connected tightly.
Could it be my manifold gasket? That's all I can think of at this point - the upper half gasket has a slight leak. Again, it can't be felt, but there is a hiss.
That said, if I unplug the ICV while it is running, the idle smooths out and climbs up to ~1500. Hiss is still there, but it sounds like air is running through the valve. Reconnect, hiss gets smaller, idle drops to ~800, rough idle but not awful.
I'm thinking it kinda has to be the intake gasket - does that seem plausible?
Thanks for all the help. The car is 98% normal now, just down to idle issues - it revs all the way to redline, has good power, is smooth, but the idle is just a smidge off.
Thoughts?
Thanks!
Iain
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Just went out and retorqued the upper manifold nuts. Tight. Bah.
I'll probably take the upper manifold off and see what's hiding under there - kinda hard to get at stuff & see it at the same time.
Iain (I should know better than to let cars sit for several months...)
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see if a shop around you has a smoke machine.... so awesome for finding vaccum leaks. Or if your in the south carolina area i have one....
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Yeah, that'd be helpful!
I'm going to take the upper half off this weekend, see what I find - I suspect it is either the gasket or a cracked hose under the manifold that I can't see - although I get the best idle improvement when I spray carb cleaner AT the ICV.
Hmmm. Who knows.
I'm in Denver, CO - no SC for me, sadly, but thanks!
Iain