GM Drivetrain & Suspension Chassis | Transmission| Driveshaft | Gears/Rear End/Differential | Traction Aids

WOT Shift Overshoot...Trans or tune?

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Old Aug 4, 2014 | 09:51 AM
  #11  
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Originally Posted by Gadgetized
I did have to lower mine a little bit as I made more power. Can you log the gear to see if it is commanding a shift? That should tell you if it is a PCM issue or a tranny issue.
Yes, I will do some trans logging once I get it back together and out to the track again. I was more concerned with the engine first time out and didn't realize what was going on until I looked more closely at my logs.

One thing I noticed in my tune is that for Normal shift mode I had the WOT shift MPH values setup so that the corresponding RPMs were 400-500 below the 5800 I was using in the WOT shift tables. For Performance mode they were only 40-50 RPM less. Not sure if this made a difference. Looking at a stock 80E tune the differences are 1400 - 2300 RPM. Probably should have left the WOT shift MPH tables stock.

Last edited by DrX; Aug 4, 2014 at 10:04 AM.
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Old Aug 5, 2014 | 10:04 AM
  #12  
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The speed calculated for shifting parameters are not the same as the speed calculated for the speedo and scanner display. Make sure you have the correct rev/mile for your tire size and gear. HPT has a sanity check for this on the gear/tire screen but not sure what's available in EFILive.

This thread may be helpful from when I had this issue after doing the 80 swap.
https://www.performancetrucks.net/fo...ft-wot-422365/
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Old Aug 6, 2014 | 08:29 AM
  #13  
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Originally Posted by BigKID
The speed calculated for shifting parameters are not the same as the speed calculated for the speedo and scanner display. Make sure you have the correct rev/mile for your tire size and gear. HPT has a sanity check for this on the gear/tire screen but not sure what's available in EFILive.

This thread may be helpful from when I had this issue after doing the 80 swap.
https://www.performancetrucks.net/fo...ft-wot-422365/
Thanks. Appears that my revs/mile was off, at least according to my calculation based on a 31.5 tire and 3.73 gears. This could have made a difference with the WOT Shift at VSS tables bumped up close to the Shift at RPM tables as I had them.

Last edited by DrX; Aug 6, 2014 at 08:38 AM.
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Old Aug 6, 2014 | 06:19 PM
  #14  
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Mine shifts right on the money after I got the shift adapt ability removed at higher torque values. I'm also running a 2-relay mod with a 60E tune. With the shift adapts left in I would occasionally have late (hit the limiter at 6600) shifts due to the PCM apparently pulling the line pressure because the shifts were "too fast". (This also caused TCC slip in 4th under load).
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