Hey Guys,
I've been having turbo issues lately. I have an SCT X4 so I"ve been using that to watch VGT duty cycle.
Truck has not thrown a single code - but the VGT has been doing everything BUT acting normal. Sometimes when I start it up, it's stuck on 0.84. Other times, it's stuck on 0.29. Sometimes when it's stuck on 0.29, when I give it enough throttle, I can get it to move, but it seems to be cycling too hard and I get into overboost territory so I lay off the throttle. The last few times I've driven it it's been stuck on 0.84, when I give it some throttle it will cycle a bit, maybe go down to 0.70, but I can just tell by the sound of the turbo that if I really give it hell it's going to overspeed/overboost the turbo.
So - am I looking at a control issue here? Bad VGT pigtail, bad VGT solenoid, or does this sound like the turbo is sticking, and I should pull it apart and rebuild it.
The truck has 365k miles. The turbo was cleaned roughly 100k ago.
At this point, I'd almost be tempted to just throw a new turbo on it - IF it's a hardware issue.

 

Solenoids are not typically prone to problems.
I would suspect, at least according to what you are describing, sticky vanes. 100k miles is a fair amount in between a cleaning.

 

 

A bad EBP sensor will make a turbo act like it is sticking.

 

Not sure I would buy anything until it's torn down.
If it's just needing to be cleaned it won't cost you much besides the turbo install kit and some scotch brite pads.

If the housing is pitted under the vanes, it's shot.
If there is too much shaft play, or the bearing housing bore is scored, it's shot

 

if there is shaft play, can it be rebuilt, or am i looking at a new turbo?

 

There will always be a little bit, it's normal and needed for lubrication.
One way to tell is to spin the front by hand, if it binds easily on housing it's toast.

I just check it with a magnetic base dial indicator if I am in doubt, but most guys don't keep one of those around.If you have access to one it's not that hard to check if you pop the front cover off.

 

 

 

Yes it would

 

It's worth a mention even if you likely did this, be sure that nipple off the intake is clear as well.

 

 

SCT X4. Only code that's stored is ICP circuit voltage low but that's a different issue that I've been dealing with before all of this.
I'm also replacing up pipes w/ BD Diesel up pipes, since my stocker was cracked. But i wouldn't that thank would cause this issue. It would mess the EBP readings up though.

 

Cracked up pipes will affect your boost for sure, I can see this perhaps messing with your other readings as well.
That over boost you mentioned makes me wonder if it's the PCM trying to compensate for your leaking up pipes. You would be surprised how much boost even small leaks in the up pipes will cause.

It's worth mentioning, if you use the BD up pipes you might want to start snugging things up from the TOP, and not the bottom as the instructions tell you.
I bought them for the kids truck last fall, and really like them, but when I did things according to the instructions I ended up with 3 lbs LESS boost than I had before with bad OEM's
I loosened the whole dang works up and started topside, worked like a charm. I have read of other guys doing it this way with this brand as well.

 

My plan was to tighten the connection to the turbo first, then the two clamps that connect the up pipes to the collector, and finally tighten them at the manifolds. Is this the way you did it?
Thanks for the tip... notice any performance difference? I guess anything is better than cracked up pipes.. but who doesn't like quicker spool up