1994 Silverado 5.7 liter high idle issue

[1bignordic]

Greetings! My '94 Silverado is having cold engine high idle issues. There is no high idle! I've replaced all kinds of sensors, etc...I even brought it into a reputable mechanic, which I don't like doing, they said they fixed it. They didn't! They said it was a rusty ground issue. I'm at a loss. The truck runs great but when I start it cold there is no high idle, I have to keep my foot on the pedal until its warm enough to run on regular idle.

Does anyone have any words of wisdom to help out with this situation? I appreciate your help!!!

Sincerely,

1bignordic

 

[skylark]

Check the coolant temperature sensor near the thermostat housing. It is a different one from the gauge. If it thinks the engine is warm it will be too lean on cold start. If someone can scan the actual values while it is running that would be better.

 

[Ironhead]

I think Skylark has the right answer to this one.

 

[sntrym]

If the CTS checks out, check the IAC. If you remove the IAC, the engine will idle around 2200 rpm. Make sure the wiring harness is disconnected when you start it otherwise the IAC will eject its guts.

CTS testing link: http://67-72chevytrucks.com/vboard/showthread.php?t=425788

 

[1bignordic]

CTS and IAC have both been replaced. Still no change. Sorry for the delayed response, my computer died! At least the '94 is still running like a champ, just not idling!

 

[sntrym]

Check the throttle plates for carbon build up. Check vacuum connections.

 

[1bignordic]

Update! How many months later! I could not find the problem so just gave up, brought in to the shop, its was a faulty IAC. Problem solved, runs like a top.