LBZ Surging

Stock 2006 LBZ 190K. From a dead start , standard acceleration, 1st and 2nd gear feel typical, shifts into 3rd and if or when the RPMs hit about 2K get noticeable power surge. Coming up on a fuel filter replacement so swapped in a fresh one. Still doing the same. I have owned this truck from brand new and it feels different. nothing else appears wrong. I have been driving my 3500 van that is a gasser most of the time as I work out of that truck so maybe it is me. Any thoughts ? Thanks in advance.

Sounds like it may be due to either fueling or turbo boost pressure variations.

In either case, codes should be set if the variation is outside of allowable limits.

A good tech with a Tech II scan tool can evaluate both fuel rail pressures and turbo operation on a ride-along.

Found out that the turbo has an issue. Computer talking to solenoid, solenoid is good. Turbo only operating at 17%.
Need to tear it down to see the turbo I guess?

What shape is your air filter in or have any critters moved into the housing?

All filters are GTG and changed regularly.
Shop is telling me that it is the Turbo. Local GMC shop stated that is not uncommon and they stock several units just for that reason.

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Originally Posted by Bravo Whiskey 21

All filters are GTG and changed regularly.
Shop is telling me that it is the Turbo. Local GMC shop stated that is not uncommon and they stock several units just for that reason.

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This is the result of continuous, poor diagnostic practice. A failed turbo is NOT common, although shops and dealers do replace them frequently. The turbo (the turbine and compressor unit), (as opposed to "the turbo", the turbine, compressor and conglomeration of parts that attach to it), in fact rarely ever fail, and normally last the life of the engine. I'm not saying your turbo has not failed, only that it is unlikely at this point, with such an inadequate diagnosis. Many "shops" and dealers have become no more than parts-exchangers, with little actual practical diagnostic experience.

Ask the shop and dealer for the list of DTC's they are basing their conclusion, and post them here, if you don't mind. If they can't/won't, then we are wasting your time, as are they.

The turbo vane control ring can crack or seize on the pilot due to corrosion. Depending where it sticks it can make the engine run kind of crazy at shifts etc. It is easy enough to disassemble and clean. We just did the turbo on my 2007. I had to pry the ring off the pilot like lid off a paint can and mine still rotated on command just a bit slow. When done it worked free as can be and actually had good clearance. It follows the commands exceptionally quickly now.

DTC P2563/4 and possible P0003A are usually present if the ring is stuck.

Went over to the shop. This is a local garage and I know the guys fairly well and as my vehicles pass out of warranty I use them. They have always been very fair with pricing and as a contractor that fills up my trucks there on a regular basis, worked side by side with the owner on local volunteer projects and we have a good relationship.
The "piston" that the turbo solenoid controls was stuck in the in position. They got it free. The turbo did not look bad. Lots of sludge around the piston , although I change the oil religiously , I was surprised at that. 192K miles and I have been using DELVAC for the most part.
This is the first thing to go wrong with the truck except ordinary consumables.
I just put my second set of brakes on it! I tow a dump trailer and a boat trailer now and then. I am going to have them replace the complete unit that contains the turbo/piston with the AC/Delco part. Not cheap but I want to keep this truck running great as a replacement is stickered at $64K and I have one in College and another in private HS. All new gaskets and solenoid switch, sensor, along with a fresh oil change ( just did it about 1K ago).

I have a suspicion that unless you split the turbo and clean the pilot for the unison ring you will continue to have issues.

Maybe I did not describe it correctly. I am having the entire unit replaced. The back part has the turbo, center contains the piston, front part I think is wear the air gets compressed. One complete assembled pc from GM.

To each his own I guess. We've done it 2 different ways:

1) R&R/clean and reinstall
2) Replaced with upgraded Garrett unit new

Some people are exceptionally cautious and figure that they don't want to be in there again so they replace the unit at an added cost of about $1650.

These turbos are highly reliable with the exception being the vane control ring sticking. Once that is fixed they are doing well again. Time will tell if they ever repeat

Thanks to all for offering info.
I was able to get a Brand new GM unit for $1253 and as it was a lot of work to get in there, so I went with the new unit instead of cleaning up the sticking part. maybe over kill but I figure I should not need to worry about this for a long time.
On another note, the truck feels brand new again. I suspect that for a few weeks it most have been intermittingly sticking until it got bad enough to throw a code. I did not realize it until it was really bad, now the truck is sing like it always had.