Another weird idle problem

[bpestilence]

This one has me stumped. Right now I am running the stock TB with the ISC but no FIAV, running a 16g turbo w/ 750 cc injectors and F/IC-8 for tuning.

I have done boost leak and vacuum leak checks. Actually after fixing a vacuum leak my problem got worse.

So, after setting base idle properly I got the car running pretty good at 800 RPM, which it will do UNLESS I go into boost. Then it will idle very high for a short time (how high and how long seems to be related to how long I was in boost), then after axwhile returns to normal. Shutting the car off doesn't drop the idle; only time.

I also tried using my spare ISC and tuned the F/IC to get zero STFC.

Has anyone heard of this before or did I manage to invent a new one?

 

[Calan]

Sounds like your ISC is out of adjustment room.

Check out this article, if you haven't already. He uses a 420a TB as an example, but the article applies to all TB's.