1990 3.1 engine idling way to high

[Panther15]

lately my engine has been idling very high for some reason which i cannot figure out. Doesnt seem to have a throttle cable issue, not sure what it could be. any help would be greatly appreciated. i gotta change the water pump this weekend anyways, one of many other things wrong with this 158 thousand mile motor lol.

[Pabz]

check your iac (idle air control valve) on the throttle body. Clean it out, it might be getting stuck. Otherwise check for vacuum leak.

[Q-Ball]

Did you disconnect the battery? Try and idle re learn. I didnt do this for about 1.5 years. The gas i save now! 1100 rpm idle down to 500 rpm idle!

 

How high is your idle? does it get any better after you drive it and warm it up?

[Panther15]

usually if i drive it for a bit it goes down. but i will go ahead and check that valve and what not. might end up doin the battery idea.

[Pabz]

usually if i drive it for a bit it goes down. but i will go ahead and check that valve and what not. might end up doin the battery idea.

 

if you clean the IAC, do the idle relearn.

[Doug Goodwrench]

I had the same problem on a '93 Olds VIN T (3.1L).

When I hooked it to a computer... it turned out to have 5% throttle angle at an idle.

Disconnecting the battery would fix the problem for a number of drives, but I replaced the TPS, and now have no problems.

 

The other guys are right though, IAC and vacuum leak are the first 2 things you should check.

 

Later.

[ns87]

after that also check the engine's coolant temperature sender. That also leads to a high idle if it isn't working

[WC-Frogger]

I have had a sim issue ...3 time the pvc line broken , valve bad or dirty iac if you can get a TECH 1a bidirectional scan tool look at the counts for tps to valve counts along with requested iac , if you computer is asking for lets say 10 counts your iac output should be with in 2 counts if it is you have a vac leak and look hard at pcv and the plastic hose and rubber hose ( ALL ) .....

[R Dubya]

so will the idle drop, but as soon as you tap or press the gas jump back up and then take a long time to drop back down, or is it just stuck high?

[WC-Frogger]

VAC leak

[Panther15]

if i hit the gas it stays high for alittle bit, then slowly goes down basicly what you said above. 2 posts up

[R Dubya]

it's either a massive vacuum leak, which you should check over anyway, but more than likely this problem is caused by tired injectors. I had the exact same problem with my 3.1 turbo engine. New injectors smoothed out the idle and the throttle response big time.