IAC valve?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jason Spears · 01-15-2003, 07:54 PM

I think my IAC valve is not working correctly on my truck ('87 GMC 4x4, 305 TBI) but I'm not quite sure. When I start the truck cold it idles fast for about 45 seconds like it is supposed to and then slows down. I'm pretty sure this is normal operation. After driveing and I put the truck in park the engine starts to idle really fast. (Sorry, no tach yet, I bought one last week end but its been way too cold outside to hook it up.) If the IAC was shot why would the truck slow down after a cold start? Could this be a bad coolant temp sensor? I want to figure this out before I start buying parts. The temp sensor is $32 and the IAC valve is $92 from GM. Thanks for the help.

Jason

01-15-2003, 07:54 PM	#1
Jason Spears Registered User Join Date: Dec 2002 Location: Stoney Creek, ON Posts: 89	IAC valve?? I think my IAC valve is not working correctly on my truck ('87 GMC 4x4, 305 TBI) but I'm not quite sure. When I start the truck cold it idles fast for about 45 seconds like it is supposed to and then slows down. I'm pretty sure this is normal operation. After driveing and I put the truck in park the engine starts to idle really fast. (Sorry, no tach yet, I bought one last week end but its been way too cold outside to hook it up.) If the IAC was shot why would the truck slow down after a cold start? Could this be a bad coolant temp sensor? I want to figure this out before I start buying parts. The temp sensor is $32 and the IAC valve is $92 from GM. Thanks for the help. Jason



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