Can't find the culprit P0046 thats it??

[MTL_Dmax]

Originally Posted by CanadianDmax

Well for all of you that were wondering...... I finally pulled the turbo apart (WHAT A PITA) and........ I only had one vane that could move at all. Its like an lb7 turbo. I guess all of you that said the turbo was bad were right, yay for you. Its still hard for me to say it. Now I guess I have to find a new turbo. Any one have some ideas what i should be looking for let me know. Its not gonna be a race truck so i don't need a stage 2 or anything like that. Thanks for everyones support on this thread... CD out

Sorry to hear that bud but I can't say I'm surprised in the least. I would either try and rebuild the one you have or if it's too far gone, I would look for another used LLY turbo to go back in. You can also swap in an LBZ or LMM turbo too but you'll need to run EFI and adjust your boost tables because those turbos operate a bit differently (they make boost quicker with less vane position but sacrifice a bit on the top end). I would call up some of the turbo reman folks (Danville, Fleece, etc) and see what they might have for stock rebuilds as well as keeping your eyes open for a good used turbo in the for sale section.

[terryk]

Originally Posted by redbull660

I forgot to add, I did talk to a Gm master mechanic in the "Ask Gm Mechanic" thing on the internet and he told me that a relearn was NOT neccesary as long as I unhooded both batterys for at least 10 minutes. He said that it would relearn on its own. Cost me $15 bucks but what the hell, so far so good.

I get a P2563 (Boost Position) that shows up in history but never matures so I never get a CEL. It's just there. One time I had an overboost with it. I borrowed my buddy's Tech 2 and did the relearn. I think a good turbo cleaning is in my future but I figured I'd try it.

I noticed if I turned on the key but didn't start the engine, the learn would come on by itself and the solenoid would sweep exactly the same as if I had commanded a relearn. The learn would be on. I played with it for a fair amount of time and I think the PCM will do a relearn all by itself.

On the downside, every time I have checked the solenoid/sensor tracking it works fine (current and %) but there is that P2563 staring at me. I've been doing a fair amount of WOTs to see if the crap will clear out but if the malf keeps showing up, I will pull the turbo and go from there.

[MTL_Dmax]

Originally Posted by terryk

I get a P2563 (Boost Position) that shows up in history but never matures so I never get a CEL. It's just there. One time I had an overboost with it. I borrowed my buddy's Tech 2 and did the relearn. I think a good turbo cleaning is in my future but I figured I'd try it.

I noticed if I turned on the key but didn't start the engine, the learn would come on by itself and the solenoid would sweep exactly the same as if I had commanded a relearn. The learn would be on. I played with it for a fair amount of time and I think the PCM will do a relearn all by itself.

On the downside, every time I have checked the solenoid/sensor tracking it works fine (current and %) but there is that P2563 staring at me. I've been doing a fair amount of WOTs to see if the crap will clear out but if the malf keeps showing up, I will pull the turbo and go from there.

With that code I would pull, clean and test the vane position sensor first then check the solenoid, then pull the turbo. Unscrew and use brake cleaner to clean the sensor first and then (with key on and engine off) use your finger on the plunger to make sure it's reading properly (ie check to make sure the % position changes smoothly from 0-100%). Let us know how you make out on that first.

[terryk]

Originally Posted by MTL_Dmax

With that code I would pull, clean and test the vane position sensor first then check the solenoid, then pull the turbo. Unscrew and use brake cleaner to clean the sensor first and then (with key on and engine off) use your finger on the plunger to make sure it's reading properly (ie check to make sure the % position changes smoothly from 0-100%). Let us know how you make out on that first.

I've run it through the tests on the Tech II a couple of times and tested the solenoid. It always passes but I agree I should pull the solenoid and check it out. I'll let you know. Thanks for the suggests.

[MTL_Dmax]

Originally Posted by terryk

I've run it through the tests on the Tech II a couple of times and tested the solenoid. It always passes but I agree I should pull the solenoid and check it out. I'll let you know. Thanks for the suggests.

It's one thing to do a sweep test on the Tech 2 but after that if you don't find anything definitive, then you should pull the VPS and check it on the Tech 2 while pushing the plunger in with your finger. You'll want to be looking for it sticking, non-linear vane % or excessive wear at the tip. If it sticks, then I would try cleaning it with brake cleaner and then use a little WD40 after to make sure it slides well and then reinstall. Check again for codes and if it returns I would try replacing the VPS as a first step for that code.

[terryk]

Originally Posted by MTL_Dmax

It's one thing to do a sweep test on the Tech 2 but after that if you don't find anything definitive, then you should pull the VPS and check it on the Tech 2 while pushing the plunger in with your finger. You'll want to be looking for it sticking, non-linear vane % or excessive wear at the tip. If it sticks, then I would try cleaning it with brake cleaner and then use a little WD40 after to make sure it slides well and then reinstall. Check again for codes and if it returns I would try replacing the VPS as a first step for that code.

I've tested the sensor a couple times in the turbo and out (manually slowly and quickly depressing it). It works fine with no issues. No signs of wear. I cleaned what little was on it. Now maybe it gets intermittent at high temps but when scanning I have never seen it mis-track by enough to throw a code. Same could be true for the solenoid. Since I don't get an CEL, it's not happening twice in a key-cycle but all it has to do it happen that once at the wrong time and you are crawling pulling 11k lbs.

I was wondering if I could insert something into the solenoid hole and press on the vane plate. Could I feel any binding? I don't see a spring in there so I doubt it would return once I pressed it. In fact, I am not sure what returns it to it's neutral position (for lack of a better term), exhaust flow?

I am going to take out the solenoid in a few minutes and check it out. I notice the manual says to replace the banjo bolt and washers. Hopefully I don't have to do that and it still seals. I really want to know how crudded up the vanes and plate are but I think removing the turbo is the only real way to know. It some point I will likely bite the bullet and just do it. I've done harder things. I have 91k on the engine so it's certainly not pristine!

[cbryant]

After reading all the good information that has been posted, I finally decided that the truck I am working on needed the turbo pulled apart. The good thing is that cleaning the turbo seems to have fixed the problem. I have attached some pictures of what the rust and soot does to the vanes and plate. I had to pry the plate from the turbo, once i cleaned everything i could move it easily by hand. Boost went from around 22psi to 34psi. I also spent about $40 from the dealer for gaskets......i definately dont want to pull this turbo again just to fix a leaking gasket. I am not a turbo expert, but i can try to answer any questions if yall have any.

[CanadianDmax]

Welcome to DF. I literally just finished putting the turbo in my truck. It was probably one of the toughest jobs I have ever done. I am just waiting for my new exhaust to come in to finish the job. I had to get a new turbo for my truck the old one was to far gone to clean. I sure hope that I solved the problem for good now.

[terryk]

Wow, this is great information. I smell a turbo cleaning in my future so this really help!

[terryk]

Originally Posted by CanadianDmax

Welcome to DF. I literally just finished putting the turbo in my truck. It was probably one of the toughest jobs I have ever done. I am just waiting for my new exhaust to come in to finish the job. I had to get a new turbo for my truck the old one was to far gone to clean. I sure hope that I solved the problem for good now.

I'm curious what was the "tough" part? Access to the bolts to get wrenches on them?