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Discussion Starter · #1 ·
I have an 02 LB7 and I've noticed here the past month and a half as the air temperature here in Indiana has been averaging in the 30s, that my truck hazes at idle. It only does this when the air temperature is cold out even after the truck is warmed up. It's not burning oil or making oil, the oil smells like normal used engine oil, I am not using more coolant than normal, it doesn't knock, it idles smooth as can be, and the performance has not decreased by any means. The injectors were replaced in 2006 under the GM warranty at 104,200 miles and the truck now has just under 180k miles. The only thing I have not checked is the balance rates. I know that'd give me a definite answer as to whether or not it is the injectors or not but what else could it be? The air temperature here yesterday was in the 60s and it was not noticeable at all. I started it up this morning when the temp was back down in the 30s after sitting for over 12 hours not plugged in and it blew a puff of blueish/whitish smoke out immediately after startup. That's another thing, when it's cold, sometimes it blows that color and other times it won't. When it's warm, it just sends out a VERY SLIGHT puff of black. The truck has EFI Live DSP5, FASS 150, Modified LBZ CP3, rail shims, and a PPE boost increase valve. I run 8oz of Stanadyne Performance Formula(Blue Bottle) to my 26 GAL tank EVERY fill up as well. I'm just curious as to what this may be because the only bad injector symptom it is giving me is the haze and nothing else. Like I said it runs great and idles smooth as could be and doesn't miss. Sometimes when it's cold and I start my truck up to go to work it will lope once or twice 20-30 seconds after starting it as well. Any help would be greatly appreciated! Thanks!
 

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Discussion Starter · #2 ·
And GM replaced all 8 of the injectors back in 2006 just to clarify. I have the papers from my local Chevy dealership. It had 8 under the "quantity" section.
 

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I have an 02 LB7 and I've noticed here the past month and a half as the air temperature here in Indiana has been averaging in the 30s, that my truck hazes at idle. It only does this when the air temperature is cold out even after the truck is warmed up. It's not burning oil or making oil, the oil smells like normal used engine oil, I am not using more coolant than normal, it doesn't knock, it idles smooth as can be, and the performance has not decreased by any means. The injectors were replaced in 2006 under the GM warranty at 104,200 miles and the truck now has just under 180k miles. The only thing I have not checked is the balance rates. I know that'd give me a definite answer as to whether or not it is the injectors or not but what else could it be? The air temperature here yesterday was in the 60s and it was not noticeable at all. I started it up this morning when the temp was back down in the 30s after sitting for over 12 hours not plugged in and it blew a puff of blueish/whitish smoke out immediately after startup. That's another thing, when it's cold, sometimes it blows that color and other times it won't. When it's warm, it just sends out a VERY SLIGHT puff of black. The truck has EFI Live DSP5, FASS 150, Modified LBZ CP3, rail shims, and a PPE boost increase valve. I run 8oz of Stanadyne Performance Formula(Blue Bottle) to my 26 GAL tank EVERY fill up as well. I'm just curious as to what this may be because the only bad injector symptom it is giving me is the haze and nothing else. Like I said it runs great and idles smooth as could be and doesn't miss. Sometimes when it's cold and I start my truck up to go to work it will lope once or twice 20-30 seconds after starting it as well. Any help would be greatly appreciated! Thanks!

Regarding the above statements and following question that jumped out at me.
First I'm going to disagree with your full faith in balance rates, heres why;

The difference between the commanded rate and the adjusted rate of fuel is defined as the "balance rate". The problem with this definition(and what the ECM outputs) is the commanded rate is seldom the actual rate. So your observed/scanned balance rates OR the acceptable range(+–4) must be corrected before they have any significance compared to each other. Even then poor balance rates are just indicators of cylinder contribution problems, NOT a sure sign of injector failure.

Note: Cylinder contribution is a function of Pressure(compression), Fuel & Air mass.

At idle, the ECM can only adjust fuel mass, so we can assume Air mass and compression are constant values specific to each cylinder at idle.

This is where your specific case gets convoluted because, as described the haze condition is triggered by Air Mass(Temp).

And the white cloud on startup condition as described is more dependent on time, namely how long the truck sits between starts.

Bottom line here is our trucks ECM's "know" proper stoichiometric ratios and (assuming all mechanical functions are sound) should never run rich enough at normal operating temps to haze at idle unless there is a fuel injection pressure or timing issue.

Contrary to your statement in red the white cloud on startup at any ambient temp almost directly points to a mechanical function fault i.e. an injector.
The white cloud is more than likely raw fuel accumulated in a cylinder while the truck sits for a long period. Fact here is mechanically sound duramax injectors need a differential pressure of 1500 psi and input voltage from the FICM to open(release the ball from the seat).
This suggest at least one of the injectors ball&seat seal is compromised enough to leak fuel under very little pressure(not running).
Finally i'd assume theres a damn good chance those suspect injectors leaking at little to no pressure will surely leak enough fuel at 5-6,000psi to make a haze at idle.

The extra heat(energy) the cylinder holds when Ambient temps are 30+ degrees higher just happens to be enough to burn the raw fuel past a visible point by the time it exits your exhaust.

Heres a link to how properly read balance rates Duramax LB7 White Smoke Diagnostics - iATN

Regardless of what you find balance rates to be, I would try the "DIY injector cleaning" process found on this forum at least once before buying any new injectors.

Goodluck
 

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I think that's pretty normal especially if you have a straight exhaust system, mine does it too and so did my 04.
 

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Discussion Starter · #5 ·
I think that's pretty normal especially if you have a straight exhaust system, mine does it too and so did my 04.
Thanks guys I appreciate the feedback. You think the haze is normal too? I am well aware the my engine is notorious for eating up injectors but I'm just kinda beating around the bush before I spend big $$$ on parts.
 

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Discussion Starter · #6 ·
Regarding the above statements and following question that jumped out at me.
First I'm going to disagree with your full faith in balance rates, heres why;

The difference between the commanded rate and the adjusted rate of fuel is defined as the "balance rate". The problem with this definition(and what the ECM outputs) is the commanded rate is seldom the actual rate. So your observed/scanned balance rates OR the acceptable range(+–4) must be corrected before they have any significance compared to each other. Even then poor balance rates are just indicators of cylinder contribution problems, NOT a sure sign of injector failure.

Note: Cylinder contribution is a function of Pressure(compression), Fuel & Air mass.

At idle, the ECM can only adjust fuel mass, so we can assume Air mass and compression are constant values specific to each cylinder at idle.

This is where your specific case gets convoluted because, as described the haze condition is triggered by Air Mass(Temp).

And the white cloud on startup condition as described is more dependent on time, namely how long the truck sits between starts.

Bottom line here is our trucks ECM's "know" proper stoichiometric ratios and (assuming all mechanical functions are sound) should never run rich enough at normal operating temps to haze at idle unless there is a fuel injection pressure or timing issue.

Contrary to your statement in red the white cloud on startup at any ambient temp almost directly points to a mechanical function fault i.e. an injector.
The white cloud is more than likely raw fuel accumulated in a cylinder while the truck sits for a long period. Fact here is mechanically sound duramax injectors need a differential pressure of 1500 psi and input voltage from the FICM to open(release the ball from the seat).
This suggest at least one of the injectors ball&seat seal is compromised enough to leak fuel under very little pressure(not running).
Finally i'd assume theres a damn good chance those suspect injectors leaking at little to no pressure will surely leak enough fuel at 5-6,000psi to make a haze at idle.

The extra heat(energy) the cylinder holds when Ambient temps are 30+ degrees higher just happens to be enough to burn the raw fuel past a visible point by the time it exits your exhaust.

Heres a link to how properly read balance rates Duramax LB7 White Smoke Diagnostics - iATN

Regardless of what you find balance rates to be, I would try the "DIY injector cleaning" process found on this forum at least once before buying any new injectors.

Goodluck
Do you think that my timing could be off due to switching my tunes with my DSP5? I drive daily in my 'stock' tune but pull horses as well in my 'tow 2' tune so I switch back and forth on occasion and once in a blue moon the dial finds it's way to the 'street/race' tune:rolleyes:
 

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Thanks guys I appreciate the feedback. You think the haze is normal too? I am well aware the my engine is notorious for eating up injectors but I'm just kinda beating around the bush before I spend big $$$ on parts.
Mine has a very light haze as well and it's only seen in the right light. I have read numerous threads asking this same question and there are many that say they see it as well.
 

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Discussion Starter · #8 ·
Mine has a very light haze as well and it's only seen in the right light. I have read numerous threads asking this same question and there are many that say they see it as well.
Mine is noticeable during the daylight too. I just assailed it was my additive along with the fuel I get. It can contain up to B20 here
 
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