02' 2500HD w/ 6.2 LS3, Poor Drivability

[AaronAutoCS]

Got it loaded, let me go do a fresh log with the stuff you need boss.

[TransGo Robert]

Got it loaded, let me go do a fresh log with the stuff you need boss.

Perfect, it seems to me like the load is not calculated correctly for the engine so it does not command the right pressure. It only really cranks up the pressure (lowering force motor amperage) properly when you are at WOT). It is a bit hard to tell with for sure but with better data it should help. What rear end ratio do you have and what tire size? It also does not seem to command the force downshift at the right time, that' why I want that info to make sure the VSS is reading correctly.

[AaronAutoCS]

cruiseNew.hpl

Hope that works!

It's a wot pull, cruise, decel (does funky things/felt funky things 3 minutes in and it shows)

[TransGo Robert]

cruiseNew.hpl

Hope that works!

It's a wot pull, cruise, decel (does funky things/felt funky things 3 minutes in and it shows)

This was a good log, it seemed to work ok at WOT except for lowering the pressure a bit during the 1-2 shift but that's not a huge deal. However when you were coasting back down it looks like your pump at low RPM is not able to keep up. You will need to look at the pressure gauge to see what it does at that point. in this screenshot you can see in the two red boxes that I put around the white trace for gear ratio that the transmission upshifted by itself back up to 2nd gear when being steadily commanded to remain in 1st. That's usually from having low line pressure, AFL pressure drops below ~46 psi it will upshift to second gear like that on its own. It could be just an AFL valve issue but what makes me think it is a main line pressure issue instead is because in the lower red box I put around the green trace for TCC slip you can see what appears to be the clutch slight grabbing on and off in the converter due to a lack of converter charge (what happens when line goes below baseline). The part that puzzles me a bit is that both times it upshifted by itself to second gear you can see the computer lowered the pressure (pink trace in light green boxes) which does not make much sense if it was just the pump that could not keep up at idle like it appears at first glance. Try to reproduce this issue while monitoring the gauge and let me know what the gauge reads when it upshifts by itself like that coasting down.
1-2 1-2.png

The other thing I would like to see are some upshifts under normal acceleration instead of WOT just to see how it commands things and how it shifts. If you could also look and see if it has a parameter for calculated engine load in % it would be great if you could log that as well.

[AaronAutoCS]

Earlybird.hpl

Here's another one with the added parameter-

Pressure on downshifts (cruising to a stop) is 45-50psi and then bumps itself up to 110psi and goofily drops back down to 45psi as it shifts from 3-2

Pressure on cruise varies 75-130psi

Decel is 75psi until you hit the brake, and then pressure immediately drops to 45psi, then pops back up to 110psi as it downshifts.

Wide open is 170 in 1/2. 150psi in 3rd, 4th is unachievable at WOT.

Gears (4x4) are 4.10 factory, 265 tires (30.9") (also factory size/calibration and perfect on the gps)

[TransGo Robert]

Earlybird.hpl

Here's another one with the added parameter-

Pressure on downshifts (cruising to a stop) is 45-50psi and then bumps itself up to 110psi and goofily drops back down to 45psi as it shifts from 3-2

Pressure on cruise varies 75-130psi

Decel is 75psi until you hit the brake, and then pressure immediately drops to 45psi, then pops back up to 110psi as it downshifts.

Wide open is 170 in 1/2. 150psi in 3rd, 4th is unachievable at WOT.

Gears (4x4) are 4.10 factory, 265 tires (30.9") (also factory size/calibration and perfect on the gps)

Thanks for all the info, sorry took me a while to get to this one. So yes no problem there ratio and speed calculated right, the factory tire diameter was only 30.47" but that's a negligible difference. The pressure you report matches the command perfectly. However what I wrote before was wrong as well as the previous attached screenshot. The two section where I put the red boxes were good part where you are in 1st gear (2.482 ratio), in between was the issue where it upshift to 2nd gear (1.482) by itself while still being commanded for 1st gear. I am still not clear what your line pressure reads on the gauge when it does that upshifting by itself. Here's a new screenshot with the red box in the right place this time where it does the problem.

Acting up.png

I am leaving for Poland tomorrow to go give a class adn won't be back till next Wednesday so let me give you some pointers as to what to do depending on what the gauge reads at that time. If the pressure is down to 45 psi or so when it upshifts to second gear like that by itself while the PCS line % is in the 30-40% range as in the screenshot then the pump can't keep up. If on the other hand it is around 75 psi then the AFL bore in the valve body is worn out, it will need to be fitted with an oversized valve.

Now that is all about this issue coasting down but does not do anything for your upshifts that you say feel very weak. The shifts look ok in the movie but it is hard to get a feel for them just looking at a log. With a higher stall the shifts feel always suffers, but since I believe you said it shifts fine at WOT and since the load does appear to be calculated properly, you might want to tweak the tune so that it raise line more. You can see in this screenshot that at 65% throttle, the calculated load is 72% but it is only boosting line pressure by 54%.

load.png

That's not right, the boost in line should always be more or equal to the calculated load %. The exception being at 100% load since PCS Line % max is 90%. It is right most of the times in the mid load % range but could be boosted up to get firmer shifts and less chance of slippage.

I hope this helps, it is all a bit challenging to explain. I am honestly surprise that you say it works so poorly considering how it looks in the log. Makes me wonder if there is not something wrong on the engine side as well.

[AaronAutoCS]

"AFL bore in the valve body is worn out, it will need to be fitted with an oversized valve."

Will pull the VB and take care of it hopefully before your return, pump is literally brand new (fun fact- this trans blew up it's pump and killed a converter simultaneously after only 700 miles, turned a beautiful purple converter black black and sent everything in for cut/clean/rebuild) but the AFL bore would make sense in this case since everything for the 80's is ancient plus 20 years of wear on the thing prior to the upgrade rebuild.

I'll come back and post results incase some other poor soul runs into this.

Drivability (in my opinion) is poor in the low speed side, just a bit lazy and does funky things like not shifting into the correct gear when told. If you drive like a prick everywhere/heavy foot it's not noticeable. I really want the transmission and shifting to "feel" proper like it did when it was bone stock and untouched (firmer is fine, but that's not the problem).
If the #3 cam bearing hadn't walked out of the original engine, it would still be stock... I wish it was.

Part of that is the low timing/gas chosen (I'm already working on a 93 table to see how that feels overall) and part of it is transmission issues providing garbage drive feedback/feel/dying in less than 1000 miles. I'd say 80% trans feedback, 20% engine tuning is the problems.

If I can't get it worked out in the long run, I'll find a nice 8.1 truck and pull the drivetrain/harness and enjoy a nice stock tow pig. LS3 can get slapped into the little 1500 silverado. All I wanted was to tow shit and enjoy some power, and I know there's folks with way more power out there driving around satiated.

I've serviced and driven around 4K different vehicles over the years so I have a good "feel" for how things should drive/act and in a perfect world, this thing would be programmed to feel like the newer Jeep/Dodge stuff (love their trans strategy, very responsive and never laggy/lazy)

Thanks for all the help Robert, hope you enjoy the trip.