Having problems with your 2005 GMC Sierra 2500HD 4WD ?
5.7 gm runs rough and back fires through the intake
\015 I have a 2000 2500 gmc and it runs rough and misses and when under heavy acceleration it back fires through the intake... I have replaced the plugs and wires and it didnt help.... What to do??\015
I agree with the timing. Your timing is way advanced causing pre-detonation and throwing your flame front and/ or unburnt fuel out through your valves and into your intake manifold. If you have gone off-roading a lot or someone has been beating on your engine or engine compartment while the engine is running your knock sensor will advance your timing to try and fix that. I agree that you should get that thing on a scanner ASAP but I can almost guarantee that you need a timing job and possibly a new knock sensor.
Repair Help & Product Troubleshooting for 2005 GMC Sierra 2500HD 4WD
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