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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15133
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2007 GMC Sierra vortec max rough idle. Runs fine under load

Customer Question

2007 GMC Sierra vortec max rough idle. Runs fine under load but shudders at low idle or when in Park.
JA: Is the rough idle intermittent or consistent?
Customer: Consistant. Mech says the fuel injectors are working properly. Just completed new plug/wire change due to mileage (114,000) but issue still exists.
JA: Are you fixing your Sierra yourself? What have you tried so far?
Customer: I'm old school mech- not up to snuff for modern systems. I do routine maint and use a ASE certified mech for anything else. Plugs, wire, even tried swapping coil packs between cylinders- nothing changed so went back to original configuration on packs
JA: Anything else you want the mechanic to know before I connect you?
Customer: Have been told by one garage I need a complete valve job on engine ($3000 minimum)another says to re-flash the computer at a dealer
Submitted: 1 month ago.
Category: Chevy
Expert:  Jared D replied 1 month ago.

Any time we see one of these trucks in for a rough idle it's almost always caused by bad lifters. They get gummed up and need to be replaced all the time.

Are you getting any trouble codes?