[V8] Idling & Starting Problems

[George Kauffman]

Recently I submitted a description of current problems with uneven idling
and a couple of smells. Well, the problems have gotten stronger. The car
won't idle for long without getting very rough and is reluctant on a warm
start (even in cold weather). Yet on the highway, it seems fine & mileage is
normal (about 18 mpg).
Now, I'm afraid to drive it all because it seems like whenever I have to
stop it is going to stall out. If it doesn't start then I'm looking at a
rollback to get it home. Just after this happened, Eddie Dial started a
discussion (0n December 15 or so) that seems to hit my car's problems
directly. Here are the specifics on my car:
1. During warm weather the car wouldn't warm start for about 60-90 min.
2. The fuel pump is loud, at least threatening the need for replacement.
3. The tachometer generally doesn't work anymore. Could that be the RPM
sensor? Or the reference sensor?
4. It's not warm idling well at all. In fact the last day I drove when it
was struggling at idle, the loud fuel pump sound was cutting in and out.
5. I haven't replaced the O2 since I had the car (about 50,000 miles).
Does anyone want to suggest how to go about solving this in the most cost
effective way? Which to do first, how to do them and where best to get parts
(an approximation of parts cost and hours of labor would be great).
Help would be *greatly* appreciated!

George Kauffman
90 Audi V8 automatic, 156,000 miles