OK, getting closer - idle issues now.

[Mannix]

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

[Mannix]

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...)

[thebigbadyeti]

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....

[Mannix]

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