E38 with T42 shifting through gears way too quick and dead pedal syndrome.

[truckfan2]

I am still banging my head on the wall with this combo. 2005 silvy 2wd got an LS3 out of a 10 camaro installed with a 15 pin 4L60E trans and I am trying to get this thing right. I swapped out the ecm for an 08 tahoe ecm and a T42 out of an 09 silverado as the T42 from the tahoe was damaged and I couldnt read it. I was having the speedo stuck at 158 issues until I unlocked another 08 tahoe tune from the repository and did a write entire to get the OS matched to the E38. Yesterday I took it for a drive and it would shift through all the gears about as fast as it could and wouldnt downshift until you completely stopped. I put the scanner on it and this time it shifted great and the TCC did its thing so life was good. I stopped and tried to do a launch and it did the dead pedal thing and now wont shift normal anymore. I have attached the tune and the drive I scanned when the pedal goes dead around 15:48. Any help would be greatly appreciated as I have wasted plenty of credits already on this thing and hope its a setting of some sort pissing it off.dave lewis 1st drive.hpldave lewis final 08 tahoe os.hpt

[blindsquirrel]

Your trans settings are set up for a 4WD (donor tune file is a 'K' VIN). Your trans settings are still identical to a stock Tahoe 4WD reference file except for torque management stuff.

[blindsquirrel]

And don't zero out Abuse Mode on Gen 4s unless you have a speific need to do neutral drops - that's the only time Abuse Mode is active. Changing that back to stock would be the first thing I'd try before anything else.

[truckfan2]

Thanks man, I pulled a tune out of the repository for an 08 silverado 2wd and moved my trans settings over to those and reenabled abuse mode. Here is the latest version I will try next. Another thing I have noticed is its running really rich with the trims hovering around -20% if you look at the drive. I noticed the camaro cal I put in it has a ton more timing and maf numbers than any of the truck stuff, should I just average them or run the truck settings? The truck is a shortbox 2wd so it doesnt weigh much compared to the camaro but it seems like a lot of timing. dave lewis final 08 tahoe os3.hpt

[GHuggins]

Typically when it shifts fast like that your missing a turbine shaft speed sensor reading from the trans. Log all of your speed sensor and shift command parameters. Usually all do to OS mismatch or wrong for the particular trans. That's if it's still doing it after loading your latest OS change.

[truckfan2]

When I first start the truck it wont shift correctly at all until I hook the scanner to it one time then its all good for a key cycle. Anybody dealt with this before? Dave Lewis final3.hpt

[Shnraines]

Do you have input shaft speed sensor on your trans?

[truckfan2]

Yes its a 15 pin 4L60.

[Shnraines]

Any dtcs?

[truckfan2]

No codes set. My concern is with the 09 t42. I have seen where folks say you can just write it how you need it and others say you cant use an 09 and up with an 08 ecm.

[blindsquirrel]

and others say you cant use an 09 and up with an 08 ecm.

You can't. Is that what you did? I thought it was pretty explicit before, about early with early and late with late and do not mix them.

[Shnraines]

Squirrel you posted this on his earlier thread


I have not found any T42 that won't interchange with any other T42. There's about 20 different service numbers and they all interchange. '08 Tahoe and '09 Silverado both have the same list of compatible numbers.

There was a comm protocol change (in the software, not hardware) in '09, if you have an early ECM you have to use the early TCM OS. Late ECM must use a late TCM OS.

[Shnraines]

Truckfan you wrote the 08 file from the repo to the TCM?

[blindsquirrel]

I'm not sure if he's confusing hardware with software. There's no such thing as an early or late T42, the hardware is the same. Writing an early TCM OS turns it into an early TCM that only talks to an early ECM, and writing a late TCM OS turns it into a late TCM that only talks to a late ECM.

Any of these numbers:
24223112, 24226863, 24230461, 24234503, 24235340, 24235776, 24239224, 24239427, 24242391, 24243901, 24251062, 24252114
can be used in anything with a T42 from 2005-2014. AFTER programming with the correct file.

[blindsquirrel]

If you mix early/late ECM/TCM, they will both show up on the bus and talk to a scan tool and give valid data, but will not talk to each other.

[truckfan2]

I used this tune and did a write entire to both the TCM and ECM just now and the thing still shifts instantly when you take off. I went to the salvage yard and grabbed a T42 out of an 08 tahoe just to make sure they would play nicely. Can you look at this tune and see if I am missing anything here. So strange that connecting it to scanner makes it act fine even if you disconnect the scanner. Next key cycle its back to the same old fast shifting stuff.Dave Lewis final3.hpt

[truckfan2]

Truckfan you wrote the 08 file from the repo to the TCM?

Yes, the original ecm I had didnt come with a T42 so I pulled an 08 stock tune and paid to unlock it then did a write entire to the T42 so I had the correct trans program. Then I used a 2wd tune to get the 2wd parameters and wrote just the calibration part of those. Could anything being leftover from the 4x4 parameters be causing this weird issue of connecting to the scanner making it shift?

[Shnraines]

Maybe it thinks it's in 4 low? Don't know why or how scanner would change anything. Did you log everything trans related in scanner?

[Shnraines]

https://forum.hptuners.com/showthrea...g-for-my-setup

Looks like you need a 2wd OS

[truckfan2]

Here is the current tune I am running and 2 scans. One with the shifting issues and one after I disconnected scanner and cycled the key and it started shifting good. Any help on this would be greatly appreciated as I am out of ideas. 08 tahoe tune file test dave lewis.hptshifting issues.hplshifting correct after scanning.hpl