Turbo issue ?

[MNStroker316]

Hey all,

I recently had an issue arise on my truck during a little road trip I was on. The issue I am seeing is the turbo will spool up to about 10-12 lbs, then all of a sudden the boost drops off to zero and the truck starts smoking and will not accelerate, as if the veins opened all the way up. The boost will stay at 0 until you let off the throttle and get back into it, and it still will only boost to 10 lbs

During this, all PIDs look normal to me. EBP, VGT, ICP all look normal for an accel situation. The only thing that is incorrect is the boost. I recent took the turbo out and cleaned it (didnt look bad at all) and also tried a different VGT solenoid, Neither of those things changed the problem.

To me it does not seem like a CAC pipe leak since I cannot hear any loud *wooshing* when the boost level drops to zero. I was told by a friend it might have to do with the internal actuator in the turbo that moves the veins (I was under the impression the VGT solenoid was the component that did this)? I'm at the point where I might just buy a used turbo and throw it in. Turbo is an 03 style.

Any input is appreciated.
Thanks

 

[ghohouston]

Sounds like a mechanical issue to me. Something with the vgt movement, solenoid, check the pigtail to the solenoid, etc. It wouldnt hurt to look for boost leaks either. Ive seen the plastic cold side pipe develop cracks, i/c boots, the o ring between the intake elbow and intake manifold, etc.

 

[MNStroker316]

Sounds like a mechanical issue to me. Something with the vgt movement, solenoid, check the pigtail to the solenoid, etc. It wouldnt hurt to look for boost leaks either. Ive seen the plastic cold side pipe develop cracks, i/c boots, the o ring between the intake elbow and intake manifold, etc.

So I tried a different Vgt solenoid, I received the same symptoms but the numbers on my CTS were reading all goofy (i.e. 85% while in gear at idle but the veins were clearly not wide open as an 85 value would be). It was a use solenoid but was "claimed" to be good.

I'll probably run through all the piping this afternoon, only thing left would be the IC connections and the intake elbow

 

[MNStroker316]

Ebp has been cleaned. No change in symptoms.
The part that's confusing me is I can get the turbo to spool full boost when I first drive the truck. This is how my drive went today.
Started the truck, let it warm up a little bit, left the house, got on the interstate. Did 1/2 throttle onto the highway (saw 20lbs boost) did a few OD locked highway pulls seeing anywhere from 20-25lbs boost. Turned around, got on it to get back onto the highway, started to boost up then no boost, and smoking. Then on the way home tried doing some more highway OD pulls and at about 10-12lbs the boost drops off and it smokes.
Made a stop for some fuel, the truck does the same thing (boosts then at some point doesn't boost at point)
As if it's resetting somehow..

I would like to note I'm seeing good fuel pressure and when the no boost scenario happens I'm getting ebp:18 psi, Vgt: 62% as in it will stay at 0 boost and those values until I let off the throttle

 

[GW03X]

Have you inspected the MAP hose?

 

[MNStroker316]

Have you inspected the MAP hose?

Yes, just did that yesterday when I cleaned the ebp. The hose looks to be in good condition. No cracks.