Turbo not lighting in 1ST GEAR ONLY after new turbo install

[Izpowered22]

Hi guys, long time lurker, first time poster here. I just finished installing an aftermarket VGT turbo and brand new 45 over injectors. I have an odd problem that is stumping me and I was hoping someone here might be able to help me out. I did search, but could not find anything relating to this exact problem. When I do a 50 mph full throttle punch, the truck downshifts and turbo lights like it should, boost to around 35 psi, and pulls hard. But from a stop or rolling first gear punch, the truck has very low power and tons of black smoke, and only makes 17 or so lbs of boost all the way through 1st gear.

I have double checked and tightened down all turbo/intercooler piping, and all up pipe bolts were torqued correctly during the install. Plus, it couldnt be a boost leak if it lights properly and pulls so hard in the rolling 50 mph acceleration I described above, right? Truck is an 06 LBZ. Any ideas or thoughts appreciated very much! I posted this on duramaxforum as well... really hoping to get this thing sorted out tonight! Thank you

 

[06gmc]

Posting more info about the truck will help

 

[Trimox]

Who did your tuning?

 

[2004LB7]

Sounds like a tuning issue to me. What rpm is it at/go through when this happens. Normally when you do as you describe it should upshift to 2nd with very little time in 1st. If its staying in 1st then the rpms should be real high as the converter will not lock. Maybe too tight of a converter?

 

[Izpowered22]

Update: The truck is throwing a ECM P2564 code, it looks like this is a turbo vane fault. Do my symptoms sound like this could be a vane position sensor? I installed the new VPS that came with the new turbo, but I still have my original VPS that was on my factory turbo. Would it hurt anything for me to throw my old VPS back on to see if this fixes the problem?

After doing some research on vane position sensors it sounds like they communicate with the ECM and you need to have them "Re-learned" with a tech 2. Is this what everyone is doing after a turbo install?

Funny you mention the trans and torque converter being a possible problem, because that's actually what it feels like when you step on it in first gear. Almost as if the converter is slipping. But I THINK that feeling of slippage is actually just the sluggishness of the turbo. I would say at this point though that it is possible the converter is slipping. But I know for sure I have 17 lbs of boost at WOT and gobs of black smoke.

As far as what its doing in 1st gear:

It does not short shift, it runs through the whole 1st gear. In my stock/ econ tune I stayed in it through 2nd and it chirped the tires on the gear change. Very abrupt, quick gear change.

 

[Izpowered22]

I would rather not mention who did my tuning because he has treated me great so far and I think this thread could possibly end up being construed as bad mouthing him. I will say he is a reputable duramax tuner. I do plan to call him Monday obviously if I cant get this figured out before then.

As far as mods on my truck:

Drop in VGT turbo
45 over injectors
modified CP3 rated 650 hp
Mike L built trans
All other supporting mods

 

[2004LB7]

Stuck vanes in the closed position could definitely give you tons of smoke on acceleration. I've had this same issue before. It was tuning but yours sounds like the turbo vane actuator or sensor