4L80E swap wont 2-3 shift at WOT

[kyotey1693]

This seems to be a fairly common issue when tuning a trans. I've been through CoolAid's guide on trans tuning and I've tried using BlueCat's numbers as well. I've even tried zeroing out the shift MPH and RPM as some suggest, but still no luck. I've tried going back to completely stock numbers as well and still no dice on 2-3 shift. It always hits the rev limiter. This is a built trans with a 2800 converter in an 01 RCSB truck with 3.73 gears, 31.6" tire. 5.7 with Truck Norris cam. The mph is within a couple MPH according to GPS.

What am I missing?

Tune and log file attached.
Trans Rev4 no 2-3 shift.hpl
New Trans Strategy Rev.1 - VE Update.4 E85 Lowered trans shift mph and rpm.hpt

[Alvin]

Have you double checked trans fluid level? A lot will miss shifts just half a quart low.

[rhackstall]

This seems to be a fairly common issue when tuning a trans. I've been through CoolAid's guide on trans tuning and I've tried using BlueCat's numbers as well. I've even tried zeroing out the shift MPH and RPM as some suggest, but still no luck. I've tried going back to completely stock numbers as well and still no dice on 2-3 shift. It always hits the rev limiter. This is a built trans with a 2800 converter in an 01 RCSB truck with 4.10 gears. 5.7 with Truck Norris cam. The mph is within a couple MPH according to GPS.

What am I missing?

Tune and log file attached.
Trans Rev4 no 2-3 shift.hpl
New Trans Strategy Rev.1 - VE Update.4 E85 Lowered trans shift mph and rpm.hpt

At a glance under speedo, your final drive ratio is wrong. Also your vss rotations for tire size is likely off which will make the trans command the shift late. Correct that first and try to make the shift. After you try that if it still doesn't shift lower the shift MPH way down for the 2-3 shift to like 70mph.

[RDF1]

Just becuase your speedometer = GPS speed doesnt mean all your settings are correct.
There are 2 calculations in the tune.

One for Speedometer which doesn't matter as far as we are concerned with your problem.
Then there is the numbers that the pcm uses for shifting.



Trans Revs/Mile: The number of trans output shaft revolutions per mile. This value is used to calculate the speed that is used for shift and TCC calculations.

VSS Pulses/Mile: This value is used to calculate the speed value for the engine routines and gauge cluster. It is the number of pulses received from the VSS sensor per mile traveled. If you know your gear, tire, and location of your VSS sensor you can calculate this value manually.



So you stated that you have 4.10 gears and a 4l80 but no tire size. Going by the numbers in your tune and 4.10/4l80 it calculates out to a 21.55" tire to equal 3839 Trans Revs/Mile. But your VSS Pulses per mile equal to a 4.10/4l80 and a 34.08" tire.
SO something isnt correct here.
If we go by your correct speedo readings with 97066 PPM then use that to determine you need 2426 in Trans rev/mile and i bet it works out better for you.

[kyotey1693]

Just becuase your speedometer = GPS speed doesnt mean all your settings are correct.
There are 2 calculations in the tune.

One for Speedometer which doesn't matter as far as we are concerned with your problem.
Then there is the numbers that the pcm uses for shifting.



Trans Revs/Mile: The number of trans output shaft revolutions per mile. This value is used to calculate the speed that is used for shift and TCC calculations.

VSS Pulses/Mile: This value is used to calculate the speed value for the engine routines and gauge cluster. It is the number of pulses received from the VSS sensor per mile traveled. If you know your gear, tire, and location of your VSS sensor you can calculate this value manually.



So you stated that you have 4.10 gears and a 4l80 but no tire size. Going by the numbers in your tune and 4.10/4l80 it calculates out to a 21.55" tire to equal 3839 Trans Revs/Mile. But your VSS Pulses per mile equal to a 4.10/4l80 and a 34.08" tire.
SO something isnt correct here.
If we go by your correct speedo readings with 97066 PPM then use that to determine you need 2426 in Trans rev/mile and i bet it works out better for you.

Man I'm sorry.. It's a 3.73 gear and 31.6" tall tire. I edited the original post too. I wasn't paying attention when I typed that part.

I used the built in calculator when I installed the gears and just assumed it populated all of those numbers for me. Can you show me the math on how you came up with the numbers?

[kyotey1693]

Just an update for anyone else following along, correcting the Trans Rev/Mile corrected my issue. Thanks for the help guys!