So I know a few other people with the same problem but each case is slightly different. ..

On cold days of course my car will idle really high when warming up, like around 2k RPM for a few minutes. However, once it is warmed up, it stays at around 1600 idle if I am coasting, and 1100 if I am just sitting at a stop light.

The car used to idle fine, then I replaced the distributer shaft (the old one was shot, was causing surging/power problems) and this happened.

Also, if I unplug the computer and allow it to reset, it'll run fine for awhile but then go back to its old ways. Replaced the IAC and rebuilt the entire TBI unit and it didn't help.

Anyone know any fixes/causes?

 

The first thing to check is actually your tach. factory tachs suck and are known to go bad, so make sure your readings are correct. Also, I believe while you're coasting, and the the vss is shooting a signal to the ecu, the rpm will be a little higher, even in nuetral.

 

Sorry I don't mean to highjack this thread but....


Did the old distributer shaft cause you car to die at idle? How did you know distributer shaft was bad?

 

When I would floor it, the engine wouldn't provide constant power, it would like buck or surge. Also, when I took the cap off, the insides were coated in rust. Also sometimes it would like flip out and the check engine light would come on, and I would have no power till I restarted it. Don't think it died a lot.

Anyway, thanks for the response r90, but the tach is good (I've hooked it up to a scanner)

 

I have a 94 tbi truck - but i idle around 550-600rpm warmed up at a light, and on really cold days, it will idle around 1200rpm for a minute til it warms up and drops down to 700-800rpm. Get out a digital volt meter and see if your losing voltage or not getting a good ground somewhere? charging system is fine right?

 

my charging/starting system is a little screwy...sometimes it will turn over like there is no battery even though there is, and other times after driving it for awhile and turning it off, then starting it back up it won't turn over for like an hour.

could a screwed up charging system cause these kind of idling problems? My battery never runs down or anything

 

well if your battery was drained and the alternator was no good it could/would, you don't have those problems though.