Boost issue

[zombie_style]

So a while back I had a "Turbo Underboost" code and took apart the turbo and cleaned the living s**t out of it, like I mean it was pitted bad and the vanes were stuck hard, but I followed the DIY that I was linked to here (DTS Articles - Turbocharger Reconditioning) and everything ran perfect for a few months.

But now it seems that the truck has lost a lot of bottom end power almost like not building enough boost low range but as soon as I pass 2000rpm all the freakin boost in the world is contained within the truck and it spools and all the power is ready at the pedal.

I did NOT change the unison ring when I cleaned the turbo as none of the slots were 'ovaled' or worn, I cleaned around the actuator that runs the unison ring as best I could making sure it was free to turn.

Could my vanes be stuck again? are there tests to I can do to make sure the actuator is actually moving? and lastly any good sources for new or re-man'd turbos? and are there any aftermarket turbos that I can slap on without an additional tune, even if there are no power gains but reliability or ball bearing that spool faster?

Any input is greatly appreciated since this is my daily driver/work horse.
Thanks in advance.

[southend]

You need to update your sig, what year is your truck? You may need to google the turbo relearn procedure. Maybe you have an exhaust leak.

Sent from my phone that somebody didn't help me get.

[zombie_style]

sorry it's an 06 bone stock, and do I still have to do the relearn if I'm using the same actuator? I checked for exhaust leaks at the V-bands and Y-pipe under the truck. Also checked over all silicone couplers last night, no leaks.

[a2elvis]

Unplug the VGT plug and see if the tone of the engine changes, that will tell you if the ring and vanes are moving. With the connector plugged in the vanes should be in the closed position while at idle, so lots of backpressure which will result in a very deep exhaust note.

I find that the more you drive the truck after cleaning the better it will get. The PCM needs to relearn VGT duty cycle.

[zombie_style]

this may be a dumb question, but do I disconnect it as the truck is running? or run with it plugged, listen, shut off, unplug, start again and listen again?

and found a write up on how to do VGT relearn,

The low power and lag problem could be a result of the sevice "Tech" not performing the VGT re-learn strategy after flashing the computer. Here is the strategy you can perform it.

KAM (keep-alive-memory) reset & VGT learn procedure

1. Drive the truck until the engine and transmission have reached normal operating temperature.
(The VGT learn procedure requires that the oil and coolant temperatures be at normal operating temperature)

2. Flash truck back to stock (Only need to do this if running a tuner or module)

3. Turn on the headlights

4. Disconnect both batteries

5. Short out + to - battery cables to each other (Make sure both batteries are disconnected before doing this).

6. Let truck sit like this for 10-minutes

7. Turn off the headlights.

8. Re-connect batteries

9. Cycle the key to the run position twice. Pause in the “ON” position each time until the wait to start lamp goes out (minimum 5-seconds) and pause in the “OFF” position each time for 10-seconds to be sure the PCM has "gone to sleep".

10. Start the truck and let it idle for a minimum of 5-minutes at normal operating temperature. This allows the PCM to learn the EGR valve closed position value. Also you will likely hear the turbo pitch change several times during this period as the PCM learns the necessary duty cycles for accurate VGT control.

11. Complete the road test Drive Cycle:
15 miles of mixed driving (*should* be enough in most cases) to allow the PCM to "re-learn" its adaptive strategy.

Note: Anytime the batteries are disconnected, the PCM will throw the P1000 code until the “Drive Cycle” is completed.


As for the Tow/Haul mode, the transmission must re-learn your driving style and loads hauled again as this was cleared when the truck was re-flashed.

this actually makes a lot of sense since I the truck was on a EDGE programmer "Hardcore" tune before the turbo 'stuck' and after I cleaned it I didn't do a relearn.

Will keep this thread updated, as this seems to be a common issue.

Thanks for the help in advance.

[southend]

Just at idle.

Sent from my phone that somebody didn't help me get.

[sinner6.0L]

an 06 does not need a vain position relearn procedure. That is only for 03 and early 04 with the inferred EBP strategy.

If your turbo center housing is pitted you're in for problems in the long run. You may never be able to effectively clean it. I bet your turbo is stuck again

[zombie_style]

ah ****, that's what I figured too, so any sources on good replacement turbos? If not I was looking at the Garret Powermax GT3788 or the 94 any word on those ones?

[southend]

Can't the unison ring be replaced?

Sent from my phone that somebody didn't help me get.

[sinner6.0L]

yes but the unison ring is stainless and doesn't get rusted up. the main problem with the ring is wear in the cam slot and vary rarely it can end up cracked from being frozen to the center housing.

The turbo center housing is cast on the exhaust side and is prone to rusting up causing more problems than coking alone. rust cannot be cleaned from the center housing, it will just reform again.

The best fight against rust is to not make short cool trips and not let the exhaust stay cold enough for moisture to collect.