07.5 Silverado 2500 LMM

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07.5-10 LMM Duramax Powertrain
07 Silverado 2500 LMM injector
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John LaClair
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Joined 2 mo ago · 11 Posts
Discussion Starter • #1 • 2 h ago
Having an issue with my LMM injector. When I first got the truck, it would billow white smoke, stall out, and drip fuel from the tailpipe. Code was on for cylinder 6 injector. Replaced that, and has since been running and driving, but I am getting a cylinder 6 misfire, no fuel related codes. Injector balance rates for the others all looked good (I believe they were all around 0.5), but the new one is reading +4 at idle. It also smokes and shudders in idle. When I push on the pedal with my foot on the brake, that balance rate goes into spec with the others, but as soon as I drop back to idle, it starts getting worse until it starts with the white smoke and shuddering again. Definitely burning diesel, but not sure if maybe the new injector is bad, or maybe there is something else it could be that I'm unaware of.

This truck is also tuned (no idea what kind of tune)
Has a FASS fuel system
Currently has a GP Sorensen injector in cylinder 6, new from Autozone in early January
I have coded the injector already, didn't change anything

Exhaust Manifold leak right at cylinder 6 (could this be causing the problem?)

Not knowing the history it coulkd well be a broken or eroded piston. Often times a failed piston creates a high positive balance rate (+15) as there is just no combustion at all taking place.

I never trust parts house injectors. Swap from hole to hole and see if the issue follows the cylinder or the injector.

Exhaust manifold leak? Not common and a potential sign of some previous issue.