I am having an issue with the idle of my 86 camaro when it starts up. It idles like the iac valve is closed. Barely runs and dies. It will idle fine most of the time after I drive it a couple miles. roughly 6-700 rpms in D 9-1000 in P. Sometimes after I drive it somewhere and come out to restart it, it idles at 1500. Sounds like it wants to break the u joints when I put it in gear. but when I get to the stop light its normal again.
Here's what I've done...
Set the base idle following chilton's and third gen
Set the tps to 5.4
Cleaned the throttle body including a gasket kit. Its clean enough to eat out of.
While cleaning the throttle body I cleaned the iac valve passage too.
Checked the intake temp sensor and coolant temp sensor. Ohms were spot on.
When I bought the car 2 months ago I had to replace the iac because it would intermittently fail. It seemed ok (would still occasionally idle to 1500) until I took it to a shop to figure out another problem that they couldn't figure out (I later figured it out). They did take it upon themselves to turn my idle screw in "because someone had messed with it"...yeah me! Following the correct procedure. I re adjusted it and it won't run when its cold. ?????? Runs like a champ everywhere else...Why does it do this cold only?

BTW, the car is bone stock with a gutted catalytic converter. Couldn't seem to locate any vacuum leaks either. Replaced any questionable hoses and sprayed carb cleaner every where I could think of that may have a vacuum leak.

 

I hope that's a typo, and your actual PS voltage is 0.54V, not 5.4V.

Check the throttle body shaft bushings for wear. If the minimum air position is set correctly and it still doesn't idle consistently, the TB may be worn.

 

Yeah .54 is what I meant.

 

Well I checked the throttle body and there is a tiny bit of play there. I assume there should be none at all but wouldn't that make my idle too high? I am wondering if I bought a faulty iac valve too. It doesn't ever idle high anymore. Anyone know what the ohms are for the cold start switch? Better check that too. I assume thats what the part is. Its right next to the coolant temp on the front of the motor. Looks like it has a fuel injector connector.

 

Try plushing the throttle blade completely closed with it running and see if it makes a difference, if theres play in the shaft its basically a vac leak-its letting air thru thats not meant to be going thru there. If you hold it completely shut does it make a difference? Try wiggling it around some too to see if you get any response from it.

As far as i know, if you talking about the cold start injector (9th injector, drivers side) it should ohm like the others i believe...

 

The 2 month old iac valve was siezed up. Now it's idling high so I am gonna check that throttle body. Probably needs fixed. Thanks

 

Ok so it still idles high but not everytime i start it. some times it idles down to around 900 in park other times it idles at like 1300. It does this when its warm as well as cold however when its cold I assume its suppose to idle high. When its cold and warming up it will idle down on its own and sometimes idle back up. Its like the iac is confused. I can't find a vacuum leak. I've sprayed ether all around the throttle shaft and nothing. I even unplugged the maf started it without the snorkle on and put my hand over the throttle body and heard no whistle. The car died quickly. I thought maybe there was an internal intake vacuum leak or something so I replace that. Still does it. EGR valve looked good. Opened and shut completely. I am starting to thing the ecm is bad but I figured there would be more issues if that was the case. My injectors ohmed at 16.3-16.5. Any more ideas?

Also, it is hard to start cold. I have to let the pump cycle, turn the starter then let it cycle again and the car will start up. If I dont' do this it won't start. Just threw that in there incase it helps diagnose. Fires up warm just fine.

 

did u fix it? have same issues

 

My new idle air control motor had froze up. Still trying to figure out the 1500 rpm idle issue though. I have done everything I can think of including a new ecm. That didn't work so I took it to a shop. They think I got a defective ecm cause they can't figure it out either. Anyone ever heard of a bad prom chip? That's just a theory...oh and my fan quit. Ecm isn't commanding it on. Checked all related parts and it all looks like a bad ecm?????

 

I shoulda read through my replies. Guess I had already announced the bad iac valve. I 're-gasketed and thoroughly cleaned the throttle body, checked base idle and tps 3 times, cts is good, changed intake gasket, changed ecm, I'm lost and so is the shop

 

I got it fixed. It was a faulty program on the prom. Got another memcal by a tgo member and the car idles just as it should.

 

So much for keeping it stock, What a great score on the L98

 

I am very excited to get this L98 cleaned up and put in. It opens up alot more options for performance upgrades in the future.