2005 Chevrolet Silverado Codes, smoke, noises

ALABAMA95

MEMBER
2005 CHEVROLET SILVERADO
6.6L
V8
4WD
AUTOMATIC
321,525 MILES

Hey, I have an 2005 Chevrolet Silverado 2500hd duramax diesel. When I accelerate it smokes grey and white from the exhaust and will make a knocking noise from under the hood. Codes read are P0303 cyl 3 misfire and P0670 glow plug module control circuit. Please help!

Saturday, August 15th, 2015 AT 9:59 AM

1 Reply

RIVERMIKERAT

MECHANIC
6,110 POSTS

Cylinder 3 misfire: I would check compression on all cylinders. Hook it up and do a live scan, check the dwell on injector #3 to see if it's even firing.

White smoke is USUALLY a coolant leak. Does it dissipate fairly quickly? If you can, see if it has a sickly-sweet smell to it. If so-coolant leak.

Grey smoke is usually unburnt fuel.

About the knocking: Is it "in rhythm with the engine-does it speed up and slow down as engine speed varies?

The P0670 is strange. I would normally think that if the glow plug is acting up, it wouldn't start. Do the highly technical test we call "the wiggle test." Wiggle all the connectors relating to the glow plug circuitry. Then clear the codes and check it.

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Saturday, August 15th, 2015 AT 9:18 PM