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Ask Gm Tech (Cam) Your Own Question
Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1672
Experience:  GM Grand Master Technician 2007. 14 year experience.
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My 2003 avalanche is backfiring when I go above 60 mph or

Customer Question

my 2003 avalanche is backfiring when I go above 60 mph or pull a load
JA: Where exactly do you think the noise is coming from? And how long has this been going on?
Customer: I think is the pcm shutting down because it thinks the torque is too high
JA: Are you fixing your Avalanche yourself? What have you tried so far?
Customer: i tried a new intake manifold gasket new plugs and everything i can form the repair manuals
JA: Anything else you want the mechanic to know before I connect you?
Customer: i had the dealership to look it it one time and they drove it and it didn't act up and they said they saw nothing wrong with it
Submitted: 6 months ago.
Category: GMC
Expert:  Ryan Schott replied 6 months ago.

can you pull codes or have any way to watch the engine data? I would guess by the description one of your front oxygen sensors has gone bad.

Customer: replied 6 months ago.
i already changed the front and rear sensors new catalatic converters new exh pipes new muffler new plugs new intake manifold new air filter cleaned throttle body and airways new pvc but this truck has no egr valve. i also tried different grades of gasoline and i tried addatives to clean injectors
Expert:  Ryan Schott replied 6 months ago.

Wow you put a lot at it, do you have access to a scan tool so you can watch your fuel trims while its acting up?

Customer: replied 6 months ago.
no I do not have a scan tool and no access to one.