LB7 Blowing Smoke under heavy acceleration

[greeenlb7]

I bought a green extended cab lb7 with 125k miles on it a few months ago and have been noticing this problem slowly getting worse. It seems to be that whenever I really get into the throttle I seem to get some type of lighter colored smoke, I believe it white with a possible tint to it. But it usually happens in the beginning of the drive even if the truck it let fully warm up and idle for 15 minutes before driving, and it only really happens when the turbo lights up. I used a block tester(combustion leak tester) the other day and it came back negative and the coolant level isn't dropping, plus the radiator hose isn't tight whenever I let it sit overnight and squeeze it, so I want to say I don't believe its a head gasket problem. I have noticed a ticking noise that I'm assuming is the injector getting ever so slightly louder than when I bought it but I don't think that's my problem. I was thinking maybe the turbo or turbo seals were going, maybe a bad valve, or it could be the injectors, I think it has to be oil burning some way because of the blue tint? any advice would be greatly appreciated, just a broke college kid trying to keep this thing going. Everything on the truck is stock besides turbo resonator delete.

Here's a video of me holding it at 3k rpms while not moving:

Source: https://youtube.com/shorts/lZCrEC_9Hpg?si=AZc4kOZhSjM7HaFN


Here's a video of it through a mirror while driving:

Source: https://youtube.com/shorts/5gTbI54L8PE?si=ygjRu3VAE5YD_By2

 

[2004LB7]

Could be oil leaking past the turbo seals

Try some injector cleaner and see if it clears any. That might tell you if it's injectors or oil

Oh, and welcome to the forum

 

[TheBac]

Time to break out the scanner and start checking injectors. Might want to check if the truck has a tune in it that you werent told about, too.

 

[jlawles2]

Blue colored smoke would most likely be oil as suggested by the leaking turbo seals.

However the ticking is the thing that triggers me to think you may have a valve guide / seal issue. I know my LLY had wear and play in the exhaust valve guides at 160k (ish) when I had them checked. Also had a similar ticking (think it was more related to valve lash needing adjusting).

 

[greeenlb7]

Could be oil leaking past the turbo seals

Try some injector cleaner and see if it clears any. That might tell you if it's injectors or oil

Oh, and welcome to the forum

What type of

 

[greeenlb7]

what type of injector cleaner should I try? I am going to try and get my hands on a scanner soon. Would it be helpful if I posted a video of the “ticking”sound? Also just letting you guys know I changed the fuel filter 1.5k miles ago just to rule that being a problem out.

 

[2004LB7]

The good GM cleaner has been discontinued. So maybe try some hot shot secret. Or a tank of bio or that HPR fuel

 

[Ron Nielson]

A little more info for you

White or Blue smoke at idle when cold​

If the smoke clears in less than 1 minute, this would be normal depending on temperature and altitude. Blue white smoke that burns your eyes is unburned fuel; cold temperatures, high altitude and excessive idle time all mean cold combustion and white smoke.

1. Possible bad injector, use the scan tool to cancel one cylinder at a time and see if the smoke clears up. However, using the scan tool to kill the injector does not reduce rail pressure in the injector and the tip can still leak fuel, cap off lines one at a time (cap is tool # EN-47589) to pinpoint injector. Also look at the balance rates, if the tip is leaking fuel then the balance rates may be out of specification. By increasing the rail pressure, we find injector nozzles that leak at idle pressure, but do not leak at higher pressure.
2. Check glow plug operation when cold.
3. Check rail pressure when engine is off, it should be 1.0-1.8 MPa (145-261 PSI) LB7 and LLY, or 0 PSI LBZ and LMM. Skewed rail pressure readings will usually not cause a hard start.
4. Excessive idle time can cause white smoke when cold due to carbon build up on the injector tips. More than 20% idle time is excessive. If the injectors have excessive carbon on the nozzle tip, then balance rates should be high on that cylinder.
5. Some LLY engines have a re-flash that addresses rough run, miss, and smoke concerns. Check to make sure the ECM is up-to-date.

 

[wydopenLb7]

Looks like turbo is pushing oil. I just dealt with the same thing...check your exhaust for oil first.

 

[greeenlb7]

Looks like turbo is pushing oil. I just dealt with the same thing...check your exhaust for oil first.

what do you mean by check it for oil, what specifically am I looking for?

 

[wydopenLb7]

what do you mean by check it for oil, what specifically am I looking for?

Unburned oil in the exhaust pipe. Can remove the front pipe (where downpipe from the turbo attaches to the rest of the exhaust that runs under truck) and have someone rev it up while you are looking and see if any oil comes out. On mine it would only put oil into the exhaust when you revved it.

 

[2004LB7]

Unburned oil in the exhaust pipe. Can remove the front pipe (where downpipe from the turbo attaches to the rest of the exhaust that runs under truck) and have someone rev it up while you are looking and see if any oil comes out. On mine it would only put oil into the exhaust when you revved it.

That's because of the higher oil pressure

 

[jlawles2]

Have you tried smelling the exhaust to see if it has a fuel smell. I know that sounds odd, but it may help pinpoint the issue faster.