Idle Issue with '99 SHO

[Rick Vavra]

Would appreciate some help with an issue that's developed on my '99 car.

I'm aware of a bad coil pack on the #2 cylinder but have been living with that issue for a while now. Recently, however, the car will not idle upon restart when the engine is hot after the ignition has been shut off. It idles fine when hot as long as the ignition has not been shut off after a cold start. The car starts and idles fine if stopped and restarted repeatedly with a cold engine.

The engine will start and run after being shut off when hot but requires the throttle to be opened with the accelerator in order to keep it running.

Any ideas as to the issue/fix?

Thanks.

 

[Izzmo]

Have you checked codes?

A simple thing to do is you might want to see if your IAC is gunked up (the little silver thing right on top of your throttle body).

 

[Rick Vavra]

Thanks very much for the reply. I did get a code indicating an IAC circuit problem and I did inspected the valve but found it was surprisingly clean. I cleaned and lubed it anyway but saw no difference. Assuming it still could be malfunctioning I've ordered a replacement that should be available today or tomorrow.

Hope that works as the situation has gotten worse. The car now is failing to idle when hot without the ignition having been shut off.

Thanks, again, for taking the time to reply with your suggestion.

 

[stephen newberg]

The looks of the IAC cannot really tell you if it has gone bad. And often they die completely when you clean them. So there is a reasonable chance a new one might correct your problem. Be sure to let us know after you get it in.

pax, smn

 

[Rick Vavra]

Thanks for the quick follow-up input on the IAC valve. The symptoms have gotten worse since I tried "fixing" the valve so hopefully the new one will be the cure. Looks like the part will not be available until tomorrow but I'll post the results after it's installed.

I appreciate your help.

 

[Rick Vavra]

Happy to report that the replacement of the IAC valve has solved the problem with the hot idle on my SHO. Thanks very much for the input and help!

Hope it's OK to post another question here. I've been a SHO fan for years with my first being a '93, then a '97, and currently the '99 and a 2012. I drive the '99 daily and am kinda attached to it. I had the cams welded some years ago and would like to keep it on the road but I struggle with the cost of replacing the coil pack on the firewall side...even at a non-dealer shop. Is anyone aware of a good tutorial/video that can guide me through that job?