Cleaning someone elses tune

New to the forum and kinda lost. I've got an 87 C-10 with a '99 Vette 5.7 and an '01 Camaro trans. Someone has already tuned it, but customer wasn't happy. I got an additional 23 hp from the truck as it arrived to me, but the trans is all out of whack. Traveling around 50 mph, if you stomp into it, it either goes neutral or revs up then slams into 2nd. I don't know enough about the trans tuning to know what needs to be corrected. If someone could look at it and help, would be greatly appreciated. If I need a log, I'll get it, just need to know which PID's to record. Thanks all.

turn your torque management back on for the trans as a start. you have way over shot MBT BTW.

I'll do that. Forgive my ignorance, but what is MBT? As is I said, someone else tuned it, and I'm trying to get it to a point that the customer is happy, without starting over. It only has a mild cam in it, otherwise it is stock

I recommend beginning with clean (OE) tune files from
the donor vehicles ('99 Vette, '01 Camaro) but also one
from a vehicle that does a better job of trans settings
(like for example my '02 Vortec van with the 4L60E).
Go ahead and use the compare function of each of
these against what you've got. A whole raft of point
discrepancies ought to show up. Prioritize what you find
different, according to the symptoms.

I doubt TM has to do with the weird shifting. TM only
applies some spark retard during a portion of the shift
cycle. Its whole purpose is to let the wimp trans shift
clean (not overpowering the frictions). Instead I'd focus
on force motor current across the shifts. If it jumps all
the way up (highest load capacity is at current=0) then
look at the rightmost column of the force motor table
(in conjunction with the little fill-box for max line %).
Some vehicles have a "blow-off" value there that if you
ever index there, will give no (or minimum) line pressure
at WOT. The limit-field is supposed to keep you out of
it, but some "smart guy" might have raised the limit to
100% not knowing that this allows you to index a bad
column and lose rather than gain holding torque.

Also look to the actual TPS voltage (not %) because
over-the-top values from TPS will engage some fault
responses in-the-moment (codes take 10 sec of
sustained out-of-bounds voltage to set, but any time
you are over 4.7V you'll see stuff like short shifting
and other weirdness relating to the PCM having no idea
about a prime input).

Forgive my asking but I've always wondered why people take on paying customers without the knowledge to do the job?

Thank you sir! Very valuable info. I've downloaded what I hope are clean OE tunes and compared them. I simply don't have the knowledge of trans cals to know what could cause the neutral or "slam shift" down to second. I was trying to avoid wiping it back to stock, but seems that may be the best option. The customer wants a daily driver with some umphh when he needs it, but the person that tuned it seems to have gone overboard a bit. Unfortunately, I've grown accustomed to a different software platform, so I'm trying to feel my way through HPT for the first time. Again, thank you.

Quote:

---

Originally Posted by 2xLS1

Forgive my asking but I've always wondered why people take on paying customers without the knowledge to do the job?

---

The primary reason I got the software was to perform the more basic operations (speedo cal, enable the PE tables on trucks earlier). This customer asked if I could look at it for him, and I agreed. I was upfront with him that I'm not an experienced tuner. I don't make any major changes, and I don't charge nearly what I have in it as far as time, because I know I'm still learning.

Quote:

---

Originally Posted by 2xLS1

Forgive my asking but I've always wondered why people take on paying customers without the knowledge to do the job?

---

Because theres all the free help you need on hpt forum.:confused:

trans is slam shifting because the base shift pressure is too high. also neutrals into 2 or 3 because the upshift and downshift mph's are too close. probably a slam on the backout shift too.

Quote:

---

Originally Posted by Jason B

trans is slam shifting because the base shift pressure is too high. also neutrals into 2 or 3 because the upshift and downshift mph's are too close. probably a slam on the backout shift too.

---

I appreciate it. I just finished changing the shift speeds back to stock and driving it, still hesitates on the downshift from 3rd to 2nd(or slams if I stay in the throttle long enough). I'm not completely sure that it's not a mechanical problem with the pack.