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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 29518
Experience:  GM Grand Master Technician 2007. 14 years experience.
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On a 2006 envoy when A/C is running it has a problem

Customer Question

on a 2006 envoy when A/C is running it has a problem starting and poor idle when turning the key on.
Submitted: 1 year ago.
Category: GM
Expert:  GM Tech (Cam) replied 1 year ago.

Hi there, I am Cam. This is a common issue on the 4.2L engine. What happens is the system was likely reset because of the battery being remove. Then when it was hooked back up, the adaptations it had learned specifically for the throttle have been erased. It then idles differently when a load is put on such as the AC or rear window defogger. To correct this, take the upper intake plenum off, the black box that says 4.2L Vortec. There are 2 10mm bolts and 2 hose clamps. Then clean the throttle plates with a rag and carb cleaner. After that, take the battery cable off and reset the vehicle. This should fix this.