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Discussion Starter #1
Hello everyone,
First post here. Some info about the truck. It’s a 2007 GMC Sierra 2500hd classic body, bone stock, no upgrades. I’ve had a 4 straight on it before and it never blew black smoke at all, up until I needed to pass emission. Reinstalled the stock pipe with the catalyst. Ran the truck and it blew a ton of white smoke. So I figured I’d pull out my snap on Solus edge and check balance rates. They look fairlygood with the exception of 2 5 and 6 which were +4 so I ran some injector cleaner and It actually cleared up the smoke. No smoke at idle but WOT will blow black smoke. So I figured leaking injectors still. Bought reman injector and installed them. And it’s still doing the same thing. Did some research, so far I’ve cleaned the mad sensor, replaced thermostat due it not getting up to operating temp. Visually inspected charge air cooler hoses for damage. Air filter it’s near new. I’m starting to question the turbo and egr valve. I’m not a 100% if a stuck unison ring would cause smoke or the egr valve. Can anyone elaborate ?
 

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Welcome to DieselPlace
Do you have an aftermarket or OEM air filter installed in the truck?
 

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Discussion Starter #4
One other I would like to add is that after replacing injectors. Do I have to reprogram my injector trim codes?
 

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Are you being tested at WOT? Have you monitored/logged vain position and fuel pressures with your scanner? What kind of boost pressures & EGT's are you seeing?

In very very simplified mechanical terms, to make X horsepower in a Diesel engine you need air in (intake), fuel, compression, which produce air out (exhaust). Think of intake and exhaust air as linear "constants" (based on parts, pipe diameters etc) increasing/decreasing w/ rpm and fuel as the controlling variable increasing or decreasing based on your right foot. You reduced the engines ability to efficiently get the air out with the stock exhaust install (or increased the restriction depending on how you want to look at it). The engine is attempting to produce the same X horsepower with the same volume of air in and less exhaust air out. The engine has to work harder to do this and the only variable that can be controlled to achieve X horsepower directly is fueling. Less efficient exhaust means less overall volumetric efficiency so some of that added fuel isn't completely burnt and exits as black smoke. Again, very simplified and takes into account nothing other than air in, fuel, combustion and air out. Its pretty late so Im not sure if it makes sense or helps at all lol.

When I had stock exhaust with the typical 5 position switch and tunes it would smoke plenty and get hot quick too. Removed the exhaust restrictions with a 3" downpipe, EGR delete, LB7 up-pipe and 4" straight pipe exhaust and in the same conditions/situations it just barely hazes if it smokes at all. EGT's run 100-150F cooler typically with sometimes 2-3 psi less peak boost.
 
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Well for starters I don’t have any tunes. It’s completely stock. I have yet to monitor those parameters, don’t have a way to monitor boost, but one thing I will add is that I’ve need I don’t get the typical rumble and hissing at idle noise. Which led me to believe that my vanes were stuck. So I finally got the turbo out and apart. Found no problem with turbo. Vains were moving freely. Could it possibly be the vgt solenoid that would make it not hiss at idle?
 

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Hello everyone,
First post here. Some info about the truck. It’s a 2007 GMC Sierra 2500hd classic body, bone stock, no upgrades. I’ve had a 4 straight on it before and it never blew black smoke at all, up until I needed to pass emission. Reinstalled the stock pipe with the catalyst. Ran the truck and it blew a ton of white smoke. So I figured I’d pull out my snap on Solus edge and check balance rates. They look fairlygood with the exception of 2 5 and 6 which were +4 so I ran some injector cleaner and It actually cleared up the smoke. No smoke at idle but WOT will blow black smoke. So I figured leaking injectors still. Bought reman injector and installed them. And it’s still doing the same thing. Did some research, so far I’ve cleaned the mad sensor, replaced thermostat due it not getting up to operating temp. Visually inspected charge air cooler hoses for damage. Air filter it’s near new. I’m starting to question the turbo and egr valve. I’m not a 100% if a stuck unison ring would cause smoke or the egr valve. Can anyone elaborate ?
My 06 LBZ has done it since the day it was brand new.
 

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Are you being tested at WOT? Have you monitored/logged vain position and fuel pressures with your scanner? What kind of boost pressures & EGT's are you seeing?

In very very simplified mechanical terms, to make X horsepower in a Diesel engine you need air in (intake), fuel, compression, which produce air out (exhaust). Think of intake and exhaust air as linear "constants" (based on parts, pipe diameters etc) increasing/decreasing w/ rpm and fuel as the controlling variable increasing or decreasing based on your right foot. You reduced the engines ability to efficiently get the air out with the stock exhaust install (or increased the restriction depending on how you want to look at it). The engine is attempting to produce the same X horsepower with the same volume of air in and less exhaust air out. The engine has to work harder to do this and the only variable that can be controlled to achieve X horsepower directly is fueling. Less efficient exhaust means less overall volumetric efficiency so some of that added fuel isn't completely burnt and exits as black smoke. Again, very simplified and takes into account nothing other than air in, fuel, combustion and air out. Its pretty late so Im not sure if it makes sense or helps at all lol.

When I had stock exhaust with the typical 5 position switch and tunes it would smoke plenty and get hot quick too. Removed the exhaust restrictions with a 3" downpipe, EGR delete, LB7 up-pipe and 4" straight pipe exhaust and in the same conditions/situations it just barely hazes if it smokes at all. EGT's run 100-150F cooler typically with sometimes 2-3 psi less peak boost.
I just wanted to say thank you to all of this information. This is the first I have seen someone quantitatively list the benefits of downpipe and exhaust upgrades

Sent from my SM-G977U using Tapatalk
 

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Well for starters I don’t have any tunes. It’s completely stock. I have yet to monitor those parameters, don’t have a way to monitor boost, but one thing I will add is that I’ve need I don’t get the typical rumble and hissing at idle noise. Which led me to believe that my vanes were stuck. So I finally got the turbo out and apart. Found no problem with turbo. Vains were moving freely. Could it possibly be the vgt solenoid that would make it not hiss at idle?
You won't hear the vanes cycle w/ a stock exhaust nor hear any hiss or rumble. At least I couldn't. If you're having vane position issues you would be setting codes. Are you 100% sure you didn't pinch a gasket/o-ring or miss/break a bolt or 2 on either side of the turbo? Its real easy to do, unfortunately.
 
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