Hey folks. I have a 1991 NA S5. I was wondering, is it at all possible to adjust the "fast idle screw" or "cam adjusting screw" with the throttle body in the car? Or is one expect to remove it, adjust, warm the car, then remove again and adjust? It just seems too inaccessible back there for my fat fingers to get at it; I can't even see the alignment marks with a mirror!

I'm doing this to try and troubleshoot a high idle/high fuel consumption problem in my 1991 NA S5 car. I took it to a mechanic for the "free" $500 of Consumer Assistance Program money after it failed a smog test, and it's never quite been the same since. Since they reinstalled the CAS off by one tooth, I can't discount that they might have tampered with the fast idle system.

I haven't discounted a vacuum leak, either, but I can't see it, hear it, or find it. I suppose they could have reconnected some of the vacuum hoses wrong. That's going to be a chore to check...

 

my 90 GXL was messed with by previous owners and stuff, it was completly driveable but just not right and that pissed me off, idleing at ~1400 rpm.
but if you remove the decel dashpot and re install the TB, with flexable screwdrivers or angled screwdrivers and such you may be able to reach those screws.
ive never had to do that though.
with the dashpot off you can get to the screw that controls the opening of the primary throttle plate, but that screw has a locknut, so take it out smere locktite on the screw and put it back. then adjust the screw with a long skinny cabnet screwdriver and reinstall the locknut.
also there should be a vacum restrictor in the vacum line to the pressure sensor, as close to the intake mani as possible.
and any electric connetor check it wih the values in the FSM. and grounding is very important.