idle started hanging up

[94opalgt]

on our way to the mustang show at summit last weekend. car starts hanging the idle at 1500rpm. now, it dont do it all the time. when we left summit it didn't do it. got in the car later that evening, did it again. i'm thinking tps or maybe the meter. any help here?

 

[Fopar]

could be TPS, but since intermittent i'd say IAC

 

[HISSIN50]

Does shutting the car off and back on make it fix itself for a little bit? If so, think TPS.

If not, the IAC idea is a good one. When the IAC hangs up, you can see some hot-idle surging as well.

Good luck.

 

[94opalgt]

if i shut the car off and start it again, the idle goes back to normal. till i drive it again and it starts hanging up again. it's not surging at all, it just sticks. or if it comes down to like 1100-1200rpm it will climb up to 1500-1600rpm by itself.

 

[HISSIN50]

Though it might not be your case, that's a sign of a bad TPS. If you have a spare or one from a buddy's car, I'd try swapping it out.

Good luck.

 

[94opalgt]

allright, found the iac screw all the way in. backed it out 1 1/2 turns, took the car out, idle still hangs up. but now it's different, i hangs at 1600-1700rpm till the car comes to a complete stop, then drops to where it should be. i'm gonna swap the tps from my coupe and see what happens.

 

[HISSIN50]

Your rolling idle should hang at around 1200-1500 RPM from the factory. This is done so the car doesn't stall while you use PS, brakes, etc but are otherwise at idle.

 

[1TallMF]

Mine randomly started doing that a while back, then I decided to take-off the IAC and clean it. It was caked in carbon crap, so I guess it was just sticking. The car has been idling perfectly ever since.
Edit: BTW the bottom screw is a b^%$# to get to, unless you already have an intake spacer on there or something.

 

[final5-0]

Mine randomly started doing that a while back, then I decided to take-off the IAC and clean it. It was caked in carbon crap, so I guess it was just sticking. The car has been idling perfectly ever since.
Edit: BTW the bottom screw is a b^%$# to get to, unless you already have an intake spacer on there or something.

I also say to give it a good cleaning

I'd keep the screw at 1 1/2 turns

Reset the pcm

Give it a couple of days to gather enough data to make sufficient adjustments

If not stable ... back it out 1/4 more turn and wait a couple more days

The key is to give the pcm enough time do its thing

You just find the best setting your car likes

Grady