LBZ odd problem...

Cknight199

Cknight199

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Aug 23, 2012
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So got my motor back together last week, and it ran awesome, on Thursday I decided to swap my .90 housing to a 1.0, so I did so, and I went for a test drive and it was laggy, smokey, and wouldn't build over 25 lbs of boost. (Used to hit 50). At one point the truck backfired when I let off the accelerator in high rpm's (3600ish). It will continue to backfire if I don't give it any throttle while its in a high rpm.

The symptoms are it literally acts like it has a boost leak somewhere, super smoky and High egt's.

I have:
Pressure tested the system, changed the turbo to a smaller s472, put my .90 housing back on, swapped ecm's, swapped maf's, replaced my IAT2 sensor, scanned it with a tech 2 and all sensors look like they are working fine.

It's literally like it has a shit load of smoke, so the fuel is there, holds rail, etc. the turbo just won't make the boost to clean it up.


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Cknight199

Cknight199

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Aug 23, 2012
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Bustedknuckles said:
You didn't leave a rag in a intercooler pipe did you? Only reason i ask is i ALMOST just did that on a lb7 injector job this morning....
Click to expand...


I thought that last night while thinking about it and got modivated thinking it makes perfect sense... I just pulled my hot side pipe and got a video of inside the intercooler and it's a clean as a whistle :/ really bummed that I can't figure it out, been at it for 3 days now with another 4-5 mechanics that know duramax' like the back of their hand and they are clueless.


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Bustedknuckles

Bustedknuckles

Honey Badger
Sep 25, 2010
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Hagerstown MD
Cknight199 said:
I thought that last night while thinking about it and got modivated thinking it makes perfect sense... I just pulled my hot side pipe and got a video of inside the intercooler and it's a clean as a whistle :/ really bummed that I can't figure it out, been at it for 3 days now with another 4-5 mechanics that know duramax' like the back of their hand and they are clueless.


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Click to expand...
Odd, it almost has to be mechanical if all sensors are looking ok and rail pressure is good. Id be looking into the y bridge to see if something is stuck in there.
 
H

Hot COCOAL

May the farce be with you
Jun 9, 2012
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Do y'all remember when I left a rag in my charge air system?
Let me tell ya, it didn't stay in the pipes!
Lol
At idle that rag got sucked into the #8 intake valve and partially pushed out the exhaust valve!!!

Good luck man, I truly hope you didn't leave a rag in there...:hug:
 
Cknight199

Cknight199

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Aug 23, 2012
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Hot COCOAL said:
Do y'all remember when I left a rag in my charge air system?

Let me tell ya, it didn't stay in the pipes!

Lol

At idle that rag got sucked into the #8 intake valve and partially pushed out the exhaust valve!!!



Good luck man, I truly hope you didn't leave a rag in there...:hug:
Click to expand...


Did it go through your intercooler??


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H

Hot COCOAL

May the farce be with you
Jun 9, 2012
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Cknight199 said:
Did it go through your intercooler??


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Click to expand...

Lol
Nope!
But that would be been somethin if it did!!!!
:cool:

I had my ssytem apart for several weeks and stuffed all the openings with rags. Well, i stuffed 2 rags in the cold side of the new intercooler and I accidentally left one of them in there when I reinstalled the charge air pipes.
:(

Yeah, it was a bad day...
 
Last edited:
Cknight199

Cknight199

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Aug 23, 2012
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What is weird is it happened within an hour of the truck just sitting, as if someone flipped a switch. I never took of my cold side pipe as well while I was swapping the turbine :/


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Harbin_22

Harbin_22

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Dec 4, 2010
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Southern Indiana
Broke crank? Mine missed acted weird when it happened. Ran fine down low, little vibration, would cut out and pop in the higher rpm, assuming from reluctor wheel flopping around, ended up throwing miss fire codes and got worst until it was done for sure. Might check your balance rates too. May have an injector stuck or something
 
Cknight199

Cknight199

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Aug 23, 2012
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Salt Lake City, Utah
Harbin_22 said:
Broke crank? Mine missed acted weird when it happened. Ran fine down low, little vibration, would cut out and pop in the higher rpm, assuming from reluctor wheel flopping around, ended up throwing miss fire codes and got worst until it was done for sure. Might check your balance rates too. May have an injector stuck or something
Click to expand...


What's odd is mine only pops when I let off the throttle, like when it's using the engine as a brake in rpm's past 3k.


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Cknight199

Cknight199

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Tomorrow I'm going to pull my crank sensor and feel my reluctor wheel. What has me so confused is it happened all at once, like I bumped a wire or something. If the reluctor wheel checks out good then I guess I'll just have to go through the entire wiring harness...


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Cknight199

Cknight199

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onebaddmaxxx said:
You could flash a 100% stock tune in and check to see if any codes are thrown like rail pressure sensor, maf, map, etc. tuner might have them turned off.
Click to expand...

going to try that tomorrow.

I am thinking that it must be something electrical, because one second the truck was running great and then after letting it sit and swapping a turbine housing it caused it to happen. If it was something mechanical it wouldn't do that instantly like it did correct?

if anyone has any recommendations I am very open minded at this point to what it could be. My sensors seem to be reading correctly, and what blows my mind is my truck has the fuel and heat to spool the turbo, but it doesn't seem to build more than 25 psi :confused:I honestly just don't know what to start looking at...
 
quinton

quinton

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Nov 28, 2011
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I bet you smashed a wire or something electrical happened while swapping housings. That's the only thing I can think of being it sat for just the swap and then acted up. You double check all your connections? Might have hit or pulled one off by accident.
 
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