Sounds like electrical. What's your MAF rate while when it's getting 25psi and laggy?
LBZ odd problem...
- Thread starter Cknight199
- Start date
Sounds like electrical. What's your MAF rate while when it's getting 25psi and laggy?
And your tune wasn't messed with? That happens running way advanced timing
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If someone would send me a PM with their email and look at these logs for me I would be grateful. Thanks
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Logs all checked out fine :/ huge thanks to Quinton for looking at them. I'm going to tear out the y bridge as well as the turbo and housing and go from there.
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Which boost did you log? Map or boost dma2? And I can't remember if that's a iat temp sensor or a boost sensor on the y bridge... But that's a very delicate wire
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Map, it's an IAT2 sensor, the truck has had that broken for years, but I replaced it just to double check and didn't change anything
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So it's not in the tune? Not a crazy amount of timing for pulse or rpm
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Nope, literally almost no timing rattle even though it smokes so bad. It was the same tune before/after the swap, even flashed in a stock tune and it does the same.
Just did a compression test and all cylinders are within 290-300 psi.
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Logs looked great other than low boost. Only thing I couldn't see was actual rail pressure but everything was smooth up to 4k Rpm.
Rail pressure checked out too. Holds 26k psi fine
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Figured it did being everything else was seeing what it was supposed to.
Tomorrow I am going to go through the engine harness. Took the turbo off today again just to triple check that nothing was off...
Could injectors be a reason its happening?
Today I noticed something weird. So I already knew it was backfiring, but I can go in more detail now. It revs up to 4k fine, but when I let off the throttle it acts fine as well. Its only when I get back into the throttle above 3200 rpm's that it will POP and white/black smoke will come out of my tailpipe. I have to give it about 50% throttle before it will respond and then it will POP and rapidly get back into the throttle.
Could injectors be a reason its happening?
Today I noticed something weird. So I already knew it was backfiring, but I can go in more detail now. It revs up to 4k fine, but when I let off the throttle it acts fine as well. Its only when I get back into the throttle above 3200 rpm's that it will POP and white/black smoke will come out of my tailpipe. I have to give it about 50% throttle before it will respond and then it will POP and rapidly get back into the throttle.
I don't think i would waste time checking the engine harness if all sensor inputs are ok according to logs. I would be looking at taking it to a shop that was very good with duramax diagnostics and had all the right tools and info to figure it out.
There Weren't any signs when I pulled the plugs and did a compression test
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Going to swap my nozzles to a stock set and see what happens...
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Just for grins, I would check all of the ground wires... I fought a intermittent fuel knock for over a year. Turns out a ground wire had worked loose at the right front of the engine
I was super pissed it was something so simple but grateful to have finally found the issue. My point is to keep it simple, good luck.
I was super pissed it was something so simple but grateful to have finally found the issue. My point is to keep it simple, good luck.