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Jake Cheek
Jake Cheek,
Category: GMC
Satisfied Customers: 24
Experience:  Automotive Technician at Hendrick Chevrolet
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Second opinion] - 4.3 starts great cold hard to start warm.

Customer Question

Second opinion] - 4.3 starts great cold hard to start warm. has erratic idle. when warm idles at 1800 rpms the drops down to 600rpms then back to 1800rpms and stays there. ran obd11 found no codes. cant locate iac location on engine. 2002 gms Sonoma 4.3,automatic*****
Submitted: 21 days ago.
Category: GMC
Expert:  Jake Cheek replied 21 days ago.

Hi my name is ***** ***** welcome to JustAnswer.

Sounds like a bad IAC valve (idle air control valve). It is strange there are no codes. I'm guessing sticking when warm. I would suggest removing and inspecting for blockages or debris, but it still may need to be replaced. Also check your throttle body for excessive deposits, use intake cleaner and clean the plate and bore.