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Discussion Starter · #1 ·
2007.5 year model with 93326 miles, 2500hd. Truck is used to carry a truck slide in camper.

My cream-puff is throwing the dreaded p2563/p003a codes. Has only occurred when idle, no drivability problem, no lag, would not know there was a problem if it were not for the cel. I have had the sensor replaced but that did not cure the problem. I have been told that the only cure is to replace the turbo. Doing some research I see some of you are having the turbo cleaned.

I am wondering if some of you would share your experiences with either replacing the turbo or having had it cleaned?

What causes the vanes to stick? I've heard carbon and corrosion, not being driven frequently. Any way to prevent it from happening?

Thanks for any thoughts.
 

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Any way to prevent it from happening?
Do the Turbo Brake mod, and use it.
Full vane sweep action keeps it free and open.
Kind of a 'use it or lose it' thing, IMO.
 

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Discussion Starter · #3 ·
My understanding is that the turbo braking is actuated by the EFI Auto Cal when in the tow/haul mode. I can hear and feel the braking action when the truck is coasting to a stop. Should the vane braking be available when the truck is not in tow/haul?
 

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Do you have the tuning for it?

Two things that are different, but work together;
Grade Braking
Turbo Braking
With the TB active and running in TH, you'll 1st feel the grade braking kick in, then a few seconds later, the TB kicks in on top of that.

Easy to hear/tell when it kicks in.....when you have a blown up pipe bellows (I recently experienced). :teehee

Whether you have the EFI Tunes to wake it up, or you do the Mod to activate the logic that's already there in your ECM for it, it's always active.
It's just more noticeable in TH because of the TC lockup, but so too is the grade braking.

If the only use it gets is with the slide-in, I'd be running in TH mode all the time with it.
 

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Discussion Starter · #5 ·
I'm thinking the grade braking is a standard feature of the Allison for that year and that the TB vane braking is instigated by the EFI Auto Cal. I think the TB braking was a standard added feature to later year models. But don't hold me to that. Lol
 

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Grade braking has always been there since '01 models.
The autocal is just an interface used to load/change tuning, a one use thing if you will.

The TB logic in the ECM was a carry over from the Medium Duty Kodiak/Topkick trucks, waiting in the wings to be activated by the mod. It's there in yours still, waiting on some pins to be installed (mod). Or, thru EFI tuning.
 

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Discussion Starter · #7 ·
Thanks for the info Hook'em.
 

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Discussion Starter · #9 ·
Lots of good reading there. It will give me something to do tonight.

What's your thoughts on cleaning a sticking vane ass'y vs. replacing the turbo? I think I want to see the actual condition of the turbo before making that decision. The tech who will do my work has cleaned many turbos and says none have come back with problems. Garrett supposedly has made improvements to the turbo linkage that should help with the sticking issue. Any thoughts?
 

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Never have run into an issue with 'em.
But all of ours run the TB and tow daily.
I'd look into doing the mod....it's like it was designed to run a TB and TH with the TC locked up all the time.

Disengaging all of that calms it down for Mall cruising ease. It prefers to be unleashed to it's natural state.
It runs it's best and quietest, when it has a load to pull.

I don't think it's a problem in design, but more lack of use.
It's okay to park 'em for a while, but once started, Diesels need to be ran and used....worked and not babied.
 

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Never have run into an issue with 'em.
But all of ours run the TB and tow daily.
I'd look into doing the mod....it's like it was designed to run a TB and TH with the TC locked up all the time.

Disengaging all of that calms it down for Mall cruising ease. It prefers to be unleashed to it's natural state.
It runs it's best and quietest, when it has a load to pull.

I don't think it's a problem in design, but more lack of use.
It's okay to park 'em for a while, but once started, Diesels need to be ran and used....worked and not babied.
So for those that do not tow very often you would still recommend activating the TB (by w/e means we have) and thereby exercising the vanes? Did i understand that correctly?

(yes, i get the worked not babied part but I dont always need to pull a trailer)
 

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I think of the TB feature as Turbo maintenance (and a brake job extender).
Engaged and running bobtail with no TH, you'll probably not even notice it as it will blend in with any grade braking action. (yes, on a steep downhill slope with a red light at the hill's bottom...it sensed a panic stop and got all kinds of busy in downshifting....no TH engaged)

Even when it's full on towing heavy, the TB is very subtle acting compared to a butterfly exhaust valve's action.
 

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Discussion Starter · #13 ·
Hook'em Horns.... been doing some searching and studying. Is there anywhere on this site, or elsewhere, where I can find locations of the various sensors on the LMM engine? I've done a lot of searching this am and found one post showing vane position sensor location but none of the pics could be found. Thanks for any help.
 

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Front top center, with the white wire going to it?
 
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