Hey guys (and gals)...

I'm new to this post but recently have found it VERY helpful in troubleshooting some ongoing problems in my car (1995 Audi 90). For some time, despite some major work performed on it recently, problems with running rich and stalling persisted. My father has worked on these cars for over 25 years and even he is becoming baffled.. we're thinking at this point it's got to be electrical.

The scope of the 'major work' performed is hard for me to communicate in every detail, but basically they did a valve job, air conditioning work, checked many possible vacuum leak areas, replaced hoses, etc., etc. They replaced the 02 Sensor.

Taking a cue from this message board, I suggested we clean the ISV and that seemed to fix the stalling problem for some time - I was so ecstatic! But the car started stalling intermitently again about 2 months after the cleaning (The check engine light/running rich problem did seem to be fixed permanently by the ISV cleaning though). He also tested the ISV before he put it back on.

I love my little car, but I'm weary of spending yet more money to have the problem persist... and I don't even pay full price!!! (I get special rates and Dad's shop!)

Any ideas would be much appreciated!
Thanx!

Amy

I think that your ISV may be going bad, sometimes when they are starting to go south a good cleaning helps to revive them for a little while. I really, really dought it got dirty and carboned up in a two month time frame! Try testing the ISV by using the Bently cd if you have it. The crankcase brether hoses can lean or richen a bank on the engine, not enough to stall it though.

I think mine is running rich, because of horrible smell... but I am not having any idling problems. I have replaced the O2 sensors recently. Maybe its the ISV then...

Mike

Crankcase brether hoses are located on the back of each valve cover. They go to the big black box on the 12 v6. These wouldn't cause stalling i don't think but may cause the engine to run a little rich. I'm not really sure though. The isv only controls air flow to keep a steady idle; does not add fuel which could cause richness. I'm not sure why you have such a bad smell in your car. Maybe burning coolant or oil? You have replaced o2's and CAT's so i really can't say.

Richness is caused in two ways:
1) Too much fuel
2) Too little air

The result is the same but the way you get there can be quite different!!

Hello! I'll try to answer some of your questions:

1) There's not very much rhyme or reason to how it stalls. I will be stable, not stalling at all for days of driving and then it will go into a cranky mode.

Even on days when it doesn't stall though, I can usually note subtle dips in the rpms when I'm sitting idling... instead of it staying constant.

Once it's in a mode to stall... rarely does it do it right away, upon start up. But it doesn't always take a lot of warming up either.

It's always pretty much a case of taking my foot off the gas and coasting to a bit lower speed - if it's in the mode to stall, the idle will dip down, sometimes so far that it's fatal. Other times, the idle will dip toward the 250 rpm level, almost to zero but will save itself and not stall. Other times I can sit for a while idling (e.g., at a drive-thru) and it seems quite stable for some time and then without warning, it stalls.

2) The running rich problem was only fixed by the ISV cleaning because when we went to take it off the car, it was visibly loose! I think it was creating a vacuum leak. So once it was replaced tightly, it seemed to fix the running rich and the check engine light hasn't come on since, even though it now stalls occasionally.

I just talked to my dad.. we're going to try replacing the ISV. I PRAY that this works. Otherwise, we must delve into the ugly and expensive world of electrical exploration. :|

Thanx guys!
Amy