2011 Avalanche, 5.3, 6L80, ALL stock, stock tune, 180k miles. After going WOT and letting off the gas the trans will slam hard into 4th, then 5th, then 6th (depending on speed, shifts are about 1-2 seconds apart from each other). Is there something I can adjust in the tune file? It downshifts into the correct gear going WOT without any issues, just slams into gear during the upshift after WOT only.
Last edited by Ls1c5vette; 01-19-2023 at 12:53 PM.
2015 Yukon SLT 5.3
I'd scan it for codes when it starts shifting hard.
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Zero codes. Trans shifts excellent otherwise.Originally Posted by Alvin
I know why the T42/4-speeds do this - run it up just before it would make a WOT shift, lift off, and it looks at the part-throttle shift table and immediately upshifts, but RPM is still high and delivered torque is low, so it doesn't pull any timing and it shifts much harder than if you'd stayed in the throttle. The 6-speed stuff is doing things much differently though, but the conditions to make it happen are the same I guess.
A copy of the tune file would be nice...
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Stock tune, no changes
2015 Yukon SLT 5.3
Do you feel delayed Drive/Reverse engagement from Park/Neutral?
May be it's time to inspect pressure switches is the TCM.
2011 Cadillac Escalade L94 w/LS3 valves and valve springs
I thought about that, but zero issues with engagement both hot and cold.
2015 Yukon SLT 5.3
Can you record a log with all PCS pressures @ high sampling rate? Prolonged air purge phase may indicate fault of the corresponding pressure switch.
2011 Cadillac Escalade L94 w/LS3 valves and valve springs
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