eatmydst1234

My car is a '93 auto coupe. When trying to start in the morning, if the ambient temp is below 65 the will not idle on its own. If I feather the throttle until the engine has a little heat in it it will idle on its own. After it will idle on its own it tries the idle at 500 rpm or less in gear, or 950 in park until it reaches operating in which it will then idle at 950 in gear or 1200 in park.
When pulling up to a light it sounds like it is trying to hunt for an idle though the tach is steady at 950.
This all started after changing the opti 2k miles ago and hasn't gotten any better. With the old opti it would start and idle fine cold but would lose spark after that, sometimes it would be 15 mins sometimes run all day.

Is this idle issue something the opti can cause? The car runs great otherwise, just wish the idle was better and at the right rpm.

AirForceOne!

Have you checked the TPS (throttle position sensor)? I have heard that this could cause your trouble too.

TGM

Is your engine throwing codes?

http://tech.corvettecentral.com/2011...trouble-codes/

I would also check your vacuum lines and move around your coil wires around to see if they are grounding.

I hope this helps!

eatmydst1234

There are no trouble codes related to the engine. Just a code for vss which I already know about. I have sprayed carb cleaner all around intake and vacuum hoses and no change in idle so I am fairly certain that is ok.

Would the check for the TPS be the same as on a L98 car? I had to adjust the tps on that one.

TGM

Does you RPMs change when you turn your A/C on and if it does it could be your IAC valve. Have you looked at your EGR?

eatmydst1234

The rpms do drop when the a/c is on. It has thrown an egr code at random, but not since replacing the egr valve. I was just worried that in some strange way the opti was causing this since it did start as soon as it was changed.

aboatguy

sounds like it could be the IAC... .... Cleaning it is simple and may fix it. A few years back I replaced mine with an autozone replacement and the car ran worse.. I did some more troubleshooting and finally cleaned my OEM IAC reinstalled it and all is well. Sucks to have a guaranteed for life part that SUCKS from the git go/

Reminds me of this

eatmydst1234

What is the best way to clean the iac?

TGM

Throttle body and air intake cleaner is your best bet. If you want to replace it I would try NAPA Auto. I never had any problems with their parts!

aboatguy

Remove the IAC before cleaning the Throttle body..

TGM

For your info the answer is no. The factory TPS is not adjustable. The only thing you can do is test the voltage between idle and WOT. They do make aftermarket adjustable TPS.

TGM

Oh you can use a toothbrush with the throttle body cleaner to clean the plunger. If it is sticking try a little WD-40 on it!

TGM

eatmydst1234

I will give that a shot this weekend. Can I get the gasket by itself or no?

TGM

It has a O-Ring that you should be able to match up at a auto store. The new IAC come with one.

92ragtop

Search and read threads on cleaning and re-setting the IAC. When you remove the TB to clean it, note that there will be some coolant spilling out. Good time to do the TB coolant bypass.

eatmydst1234

I'm not too concerned with bypassing throttle body. I will search cleaning and resetting iac however. Thank you