Really Hard Shifting with 87 Tune

[HostileJava]

2002 Avalanche 2500 8.L, just got an i2030 to adjust for larger tires and try the different tunes. I plugged in the new tire size, sent the 87 tune, and that all went smooth. First trip around the block and I thought I was going to break something. The tranny was shifting so hard the entire vehicle was banging and shuttering on every shift. It was so bad that I pulld over and restored the backup, I thought if I kept going something was going to break before I got back home. After restoring the backup everything was fine and shifting was smooth. It's an older truck but only has 55k miles on it. It's not supposed to be like that is it?

[06MonteSS]

2500hd truck with the 8.1L engine.. so that has the Allison tranny?

[HostileJava]

2500hd truck with the 8.1L engine.. so that has the Allison tranny?

4L85E, same as the Suburban 2500 of the same vintage basically.

[06MonteSS]

odd.. normally those 2500's with the 8.1 usually have the allison tranny.. which can not be tuned/adjusted, and requires a custom tune to put the tranny settings back to stock so that hard-hitting issue doesn't happen with the allison's..

if you have a normal GM tranny, then the shift pressure is usually cranked up about 20-25% higher than stock, so when you install a tune, modify it and lower the shift pressure down by -15 or -20% and see how that is for ya..

[HostileJava]

I don't specifically see something called that, maybe I am looking in the wrong spot but this is what I see(sorry for the poor quality, my phone was having trouble focusing in the dark): Would it be part throttle shift pressure?









I did do as suggested by support and restore my back and then send the tune without modifying anything, that however did not result in any chang to the shifting issue.

[HostileJava]

So I tried messing with the settings for part throttle shift pressure and upshift MPH on the 87 tune but they seemed to have zero affect on shift time or hardness. I went back to stock again. I'm really hoping someone can figure this out. Of course I'm not entirely sure I'm doing it right as there appears to be no manual for this unit yet?

[HostileJava]

So I went digging through the forums and found this:

https://forum.diablosport.com/viewtopic ... he#p276371

https://forum.diablosport.com/viewtopic ... he#p257903

https://forum.diablosport.com/viewtopic ... he#p248823

https://forum.diablosport.com/viewtopic ... he#p248657

None of the threads seem to have resolutions, is this an ongoing issue with the 8.1 and 4L85E and Diablo built in tunes?

Just throwing it out there, but I'll be down in FL next week for a week........

[mike_m]

So I went digging through the forums and found this:

https://forum.diablosport.com/viewtopic ... he#p276371

https://forum.diablosport.com/viewtopic ... he#p257903

https://forum.diablosport.com/viewtopic ... he#p248823

https://forum.diablosport.com/viewtopic ... he#p248657

None of the threads seem to have resolutions, is this an ongoing issue with the 8.1 and 4L85E and Diablo built in tunes?

Just throwing it out there, but I'll be down in FL next week for a week........

The guys that can help us are at SEMA this week, but if you can send me copies of the files in your Tunes folder (the i2 must be married), I can have them whip something up next week. Please include a line or two in your email as to why you're sending the file so I have something to reference.

[email protected]

[HostileJava]

I have been emailing back and forth with Garrett from support, I sent him backups a day or two ago but haven't heard back I'd they are the correct files.

[mikel]

you should have a new file today.

[HostileJava]

Thanks! It will be about a week till I can try this now. We are about 1100 miles from home this week, don't want to risk it.

[HostileJava]

I responded to the email as well, but I think I am having this problem with the custom tune now.

https://forum.diablosport.com/viewtopic ... 62&t=52928

[HostileJava]

I just wanted to follow up here in case anyone else comes across this thread with the same problem. Support was able to resolve this. I sent them a backup of the tune and they were able to adjust the shift firmness.