High idle

[90GMCJim]

Good morning and happy new years

I have recently noticed a high idle on the jimmy. Drives good with no problems. Just a high idle.

Replaced the IAC valve and the TPS. Since the TPS replacement I noticed when first starting it’s a little rougher on the idle surging like it wants to die then it goes back to high idle

I also noticed something clicking pretty frequent in the engine bay as I let it warm up.

EGR valve is a few months old. Also just replaced the PCV valve.

Any ideas of what it could be?

 

[sweetk30]

huge common problem with the tbi is the base gasket to the intake . they age out and suck in making a huge air leak for higher rpm at idle .

 

[shock88]

an old school check of air leaks is to spray brake cleaner/carb cleaner on the suspected areas, but a TBI base gasket isn’t all that involved to replace to ensure it’s good.

 

[90GMCJim]

Thank you. Just ordered a base gasket.

 

[sweetk30]

Why not do testing and not parts swapping . Its cheeper .

 

[shock88]

i should have added, if you do spray carb cleaner on the engine parts for testing while it’s running, and it does actually have a leak, you will hear and probably even feel a stutter/misfire, that tells u it sucked in the carb cleaner essentially.

 

[90GMCJim]

Why not do testing and not parts swapping . Its cheeper .

Base gasket is cheap. I’ll replace it then spray the carb so see if it leaks. I also have some valve cover gaskets I need to replace. While I’m there

 

[formercruiserhead]

I found my throttle was worn and wasn't actually returning all the way back to the idle stop. As a temp fix I put a weak return spring on like a carb has to help force it back to idle. Takes a small blip of the throttle to get it to set. I have another used throttlebody for it but am starting an LS swap so will be leaving it alone. Ebay has some fairly cheap reman tbi units if that's what it is. Or find a place that'll still rebush the throttle shafts for you.