LML Turbo Vane Trouble

I have been fighting an issue on some LML trucks and in pretty much in all operating systems where the turbo desired and actual boost do not follow eachother. Please see the attached log file. It appears that when the truck transfers from Open loop VGT to some other vane control table the turbo vanes actually open up rather than closing down.

I see this has been discussed before but is the resolution that there is a series of tables not mapped out by EFI live that we don't have access too? Similar to the LMM I would expect there to be a turbo vane min and max set of tables. I don't see this being tied to EGR, MAF or a max airflow table, I have logged and not found any correlation.

Thanks for any assistance.

Attachment 20138

I have trouble with this also, I have been able to make it a little less noticeable by closing up the open loop tables so it's a little less laggy transitioning from open to closed loop, but when your already cruising in closed loop it doesn't help. It would be nice to have some more stuff for boost control, I'm fighting one that acts fine normally and I get what I ask for until a 12000+ load is pulled up a steep grade then it will wig out open the vains and throw a P2263.

I believe the vane change is tied to load in some way. Sure wish we had the proper tables. I am seriously considering going away fro the factory charger just because of that. I like the turbo brake is the only thing that could keep me using it along with the right tables for adjustments.


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Thanks for all the help. I figured it out in hex. There is a slew of tables not mapped out for turbo control alone.

Can we get them added in EFI then?

I have also had the P2263 on a few truck only when pulling huge trailer up a long hill, would sure be nice to have the tables added.

Sounds like a similar problem i have with a 17 Colorado (Aus model)

I see a 30-45kpa difference between desired & actual & get turbocharger underboost dtc's

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I would love to be able to expand on the vgt table above 50mm3 of fuel. I feel that is killing these bigger chargered LML vgt guys.

getting a P2263 in a LML swapped '76 GMC I have. after pulling a light load up a grade.

Any ideas? Its got to be tune related, all hardware is verified to be fine.