4l60e WOT torque Management 1 - 2 shift

I'm running a mostly stock 5.3 LH6 with a 4l60e from a 2005 Trailblazer. E40 ECM T42 trans controller. I had the transmission performance rebuilt by a reputable builder so its good for some abuse. I'm trying to firm up and reduce shift times but the WOT first to second shift has a significant torque reduction throttle blade closure that I can't seem to alter. The 2-3 WOT shift has no TM and performs as commanded. I've changed values in all of the transmission torque management tables (including zeroing them out) but it has no effect on the 1-2 WOT shift. Data logs show the throttle blade closing to about 35% and then re-opening, which takes about 400 ms. The logged shift time is between 730 to 750 ms. The throttle blade action is consistent no matter what the values in the TM tables. The commanded time is 350 ms. The 2-3 shift is about 350 ms as commanded. I'm sure I'm just missing a setting or table value somewhere but I cant seem to find it. What am I missing?

The 1-2 should be able to complete in around .300 in a bone stock trans, I'd be real concerned if I had a 'built' unit that wouldn't do it any faster than what you're seeing. Have you done an adaptive reset, or changed the adaptive settings to disable that feature?

As far as the tune settings, it's real, real hard to say what you might be missing when you don't post the file.

2006 LH6, stock trans so I do still have a bunch of Shift TM in it because I don't like walking. But it makes the 1-2 in .300, 1-2 is commanding .250 across the board.

Attachment 112417

Part throttle 1-2 shifts are good, just seems WOT that has the problem. I'm just running this vehicle at the track so WOT performance is my focus.
I've attached a log and tune. This is my first attempt at tuning an automatic transmission so i'm not very familiar with the settings. I don't know what the adaptive functions are.
It seems to me that the ecm performs a torque reduction with the throttle blade first and then the shift occurs which makes for a horribly long shift. I was expecting that if i could successfully eliminate the throttle closure the shift time would be as commanded.

The throttle closure is happening because you are hitting your rev limiter before completing the shift. The rev limit is 6500 and set to ETC. Your transmission is looking to see 38mph, and 6200rpm before commanding the 1-2 shift. Start by lowering your commanded rpm/mph on the WOT 1-2 to allow a little more buffer between commanded and rev limit.

Personally, I would start by lowering the commanded WOT shift RPM on the 1-2 to say 6000 and make a pass to get data without being on the rev limiter (hopefully). If it still hits the limiter, bring the MPH down from the 38 and make a pass

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Originally Posted by village_idiot

The throttle closure is happening because you are hitting your rev limiter before completing the shift. The rev limit is 6500 and set to ETC. Your transmission is looking to see 38mph, and 6200rpm before commanding the 1-2 shift. Start by lowering your commanded rpm/mph on the WOT 1-2 to allow a little more buffer between commanded and rev limit.

Personally, I would start by lowering the commanded WOT shift RPM on the 1-2 to say 6000 and make a pass to get data without being on the rev limiter (hopefully). If it still hits the limiter, bring the MPH down from the 38 and make a pass

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Thanks for that review. I got caught up thinking it was torque management and didn't look at the peak rpm in the shift. Makes more sense to me now. I'll drop the rpm shift point as suggested and change some rev limit values to confirm.

Nothing in my posts was about part throttle, dunno where you thought it was. WOT 1-2 should be able to finish way quicker than .700 in a built trans.

Adaptive settings are at Trans > Shift Pressures > Adaptive

Reset adaptives is in the scanner under special functions. My trans used to do a thing where after a while it would forget it was supposed to shift fast and it would revert to ~1sec shift times, clearing adaptives brought it back to what was commanded in Shift Timing. I think the reason it got confused was at that time I had timing all zeroed out, since it was changed to .250 the issue hasn't returned.

Quote:

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Originally Posted by blindsquirrel

Nothing in my posts was about part throttle, dunno where you thought it was. WOT 1-2 should be able to finish way quicker than .700 in a built trans.

Adaptive settings are at Trans > Shift Pressures > Adaptive

Reset adaptives is in the scanner under special functions. My trans used to do a thing where after a while it would forget it was supposed to shift fast and it would revert to ~1sec shift times, clearing adaptives brought it back to what was commanded in Shift Timing. I think the reason it got confused was at that time I had timing all zeroed out, since it was changed to .250 the issue hasn't returned.

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Village_idiot provided some insight regarding the rev limiter after reviewing my tune and scan. I didn't notice that the engine went over the 6500 rpm limit setting when the shift was occurring (looked to be about 6550). Stands to reason that is my throttle reduction and I confused it with a TM issue. I'll adjust the shift points a litttle lower to provide more room to stay under the 6500 rpm limit. Once I have that taken care of I expect that the shift time should shorten up. I agree that the shift time should be much faster and I'll work on that with timing and pressure mods once I get the limiter throttle issue resolved. Thanks for the info on the adaptive settings, I'll check that out as well.

I understand the separate limiter issue but the limiter doesn't affect how quickly the band applies, or override the shift timing tables. That's down to trans internals and I suspect you have a problem there.

Yeah I see what you're getting at. I hope to get to the track on Friday and get the limiter issue resolved. Once that is out of the picture I can get a clearer indication of the shift timing.

Got to the track with it 2 weeks ago, the rev limit issue was resolved and 1 - 2 shift time was about .5 seconds. Second run of the night the 3rd gear clutch pack fried and that was it. Took it back to the builder and he repaired it and checked pressure circuits and replaced pressure control solenoid. Ran it last night and 1 - 2 shift time was in the .3 second range and 2 - 3 was .275. Obviously an internal pressure issue, so looks ok now. I'm logging solenoid current values, pressure and engine torque and all looks in line. Thanks for the help with this.