6L tune issues

[Mogman]

I know this is a little off topic but I also know many of you have experience with the 6L transmissions.
I have a stand alone 6L80 behind a 6.2L diesel, everything is going well but I need to get into the tune to adjust the shift points as I have to lift the pedal to get it to shift.
The stand alone controller/harness has an OBDII connector to talk to the transmission, my EFILive V2 can auto detect the correct controller (T43) but will not upload the data to my laptop, it goes through all the steps to "read" then says no data.
I was wondering if anyone else has ever had this issue and also I wonder if I should try and get a tune and see if I can load it, the stand alone folks say the corvette tune is best but probably any 6L80 tune would do.

EDIT, I found some tunes but I am on the fence about trying one yet.

 

[JoshH]

You're probably going to want a tune from an Express van with a Duramax. Shift points from other tunes will probably be too high for use behind a 6.2 diesel.

 

[Mogman]

THAT is a GREAT idea, thank you Josh!!
Now does anyone have that tune for the 6l transmission??

I did manage to flub the TPS calibration so it does not think the throttle is as far open as it actually is and now I can see just how GREAT this conversion is going to be!!!
I am not sure what the deal is with the TH400s they put behind the 6.2L in the HMMWV but I always thought it was a VERY POOR match as the TH400 is the least efficient light duty transmission ever built by GM, sure you can put a ton of HP in front of it, actually you NEED extra power to overcome the losses.

I have gone from a whopping 27.4 sec from 0-60 to under 20 sec
I have also gone from 2900 RPM at 60 MPH to 1800 RPM, even in 5th it is only around 2300 RPM what an improvement, it cruises comfortably at 70 now at 2150 RPM.

I have also just picked up a 2009 GEP 6.5L turbo with only 100 mi on it, that 1800-2200 will be right up that engines alley!!!!!

I still cannot read the TCM tune, it goes all the way to "read" then says no data, the stand alone controller has up to 2 programmable CAN terminations available but that is not helping, I am thinking it is a tune issue not communications so after going for a ride today I am going to try and dump a tune into the TCM and see what happens, if that works I can try and hunt down the van tune..

I am ecstatic about this conversion, I believe I am the first to install a 6L behind a Detroit in a Humvee

 

[Mogman]

THAT is a GREAT idea, thank you Josh!!
Now does anyone have that tune for the 6l transmission??

I did manage to flub the TPS calibration so it does not think the throttle is as far open as it actually is and now I can see just how GREAT this conversion is going to be!!!
I am not sure what the deal is with the TH400s they put behind the 6.2L in the HMMWV but I always thought it was a VERY POOR match as the TH400 is the least efficient light duty transmission ever built by GM, sure you can put a ton of HP in front of it, actually you NEED extra power to overcome the losses.

I have gone from a whopping 27.4 sec from 0-60 to under 20 sec
I have also gone from 2900 RPM at 60 MPH to 1800 RPM, even in 5th it is only around 2300 RPM what an improvement, it cruises comfortably at 70 now at 2150 RPM.

I have also just picked up a 2009 GEP 6.5L turbo with only 100 mi on it, that 1800-2200 will be right up that engines alley!!!!!

I still cannot read the TCM tune, it goes all the way to "read" then says no data, the stand alone controller has up to 2 programmable CAN terminations available but that is not helping, I am thinking it is a tune issue not communications so after going for a ride today I am going to try and dump a tune into the TCM and see what happens, if that works I can try and hunt down the van tune..

I am ecstatic about this conversion, I believe I am the first to install a 6L behind a Detroit in a Humvee, most go for the same 4L80 that was installed in later models behind the 6.5, same dang transmission as the TH400 only with OD and TCC, the 6L was designed 50 years later when economy was important.

 

[Mike L.]

You are totaly wrong about the 400. It used a vacum control valve to shift it and in most cases wasn't adjusted correctly or the vacum lines were crossed or the valve itself failed.

 

[Mogman]

I have been dealing with the TH400 for over 45 years, I have had MANY of them over the years and I am not wrong, they are an energy inefficient transmission, and the HMMWV has NO vacuum it uses a cable similar to the 700R4 and shifting is not the issue.

Anyway after fudging the TPS it shifts reasonably well, I have knocked almost 7 seconds off of the 0-60 times by keeping the engine in its favorable RPM range.
Even if I cannot ever read/write the TCM I can live with it!
Worth every damn penny!!!

 

[Mike L.]

You are wrong.