CTS-V 6L90E Reduced TQ Management Shift issues

[slo895.0]

I reduced my transmission TQ Management to ~50% in part throttle areas and tapering off to ~15% at WOT shifts. After doing this i hit the fuel cut briefly during my 2-3 shift when i have traction control turned on. you can see the AFR spike to ~20:1 for a split second.

If i turn off the traction control i don't have this issue.

I am commanding 6300 rpm shifts and the 2-3 shift goes all the way to my fuel cut rpm which is 6500 rpm.
I tried increasing TQ Management to 36% for 2-3 shift but it didn't help.

Beside for returning TQ management back to stock what can i do to make my transmission shift when i want it to?

View from frames 3950 to 4100 to see the issue.

Thanks for any help.

Custom 4.5'' Intake 2-18-15 Virtual VE needs tuning. reduced TQ Management.hpt2-3 shift issues frame 3950-4100.hpl

[DSteck]

Just because you command the rpm doesn't mean you will achieve it.

FYI, traction control inhibits up shifts if it is active, so if you're spinning and traction control is trying to stop the spin, it won't let you upshift. You'll hit the limiter no matter what.

You should be adjusting the shift mph.

[slo895.0]

ok, so do i just zero out the shift rpm's and set the shift MPH to the desired MPH? i also understand that commanded is not always what you will get, but i did not have this issue until modifying the TQ Management. My 2-3 shift was just fine with the stock TQ Management settings, it would shift right at or close to the commanded 6300 RPM. So why am i now unable to get the transmission to shift @ 6300 RPM?

Also my shift MPH are set a little bit low. 6300 rpm is ~63 mph but i am set to shift at 57 mph. The reason i mention this is the car always shifts around 62-63 mph, how do i get the computer to use MPH and not RPM?

Thanks DSteck

[DSteck]

Set the shift RPM to where you want it to shift, and adjust the mph to make that happen.

Reducing torque management means the engine is not pulling back power while the transmission tries to complete the shift. This makes it more likely to sail towards the rev limiter.

The shift mph is when the shift process BEGINS, and not when it actually completes. It takes time for the shift to occur. The oncoming clutch has to fill, then the offgoing clutch has to release, and then the oncoming clutch has to engage. It's automatically using mph.

Log Trans Current Gear. You'll see that it'll show the next gear at the commanded mph even though the shift doesn't complete until later.

[slo895.0]

ok ill give that a shot.

Could i add pressure to speed up the filling process in an attempt to speed up the shift process? Or do the adaptive features of the transmission do that automatically when you reduce the shift time?

[DSteck]

You'd have to increase oncoming pressures. It sounds like this is purely a shift timing problem.

[slo895.0]

im about to go make a quick run and see how it reacts. Thanks for the help DSteck.

[slo895.0]

Well that did work, but because of the reduced Tq management it does spin a tad when changing gears which engages TCS. Is there a way to "reduce" the effectiveness so to speak of the TCS? I would like if the car was allowed to chirp the tires and not engage the TCS. Can I make an adjustment to the Delivered DC Max or Min to achieve this result? And if so which one should be adjusted and in what direction?

[DSteck]

Don't use traction control, pussy.

[slo895.0]

Haha I'll take that as a no.

[8850]

I bet you will et faster if you bring your shifts down from that 6300 rpm.

[slo895.0]

What shift RPM do you recommend, and at what time do you typically raise the shift RPM?

[8850]

What shift RPM do you recommend, and at what time do you typically raise the shift RPM?

6000 or 6100 assuming stock cam. I don't feel supercharged engines need to shift above peak hp as do n/a engines.

[slo895.0]

Was your car faster when shifting at 6000 vs 6300?

[8850]

Have not tried 6300. I did try 6000 and 5800 and did not read any time differences via my HPT than what differences one scan vs. another with no tune changes. All I can suggest is to give it a try when at the track.