4l80e shifts won't shift until redline

[bubba68ss]

I have a 2003 6.0 with 4l80e DBC swap in 89 FS. It will not up-shift until almost redline. The only things that seems to affect it and get shifting closer to where it should be is if I change VSS pulse/revolution from 40 to 20. Trans is an early 90's 4l80 with newer harness and solenoids. I've tried multiple tunes and PCM's (DBC, express van PCMs from 03 and a few 03 Silverado PCM's with the IAC drivers). Any ideas on what I can try next? I am using OS 12592618

[joecar]

Post tune file.

Your 4L80E should have a 40x VSS reluctor...

do you have ISS connected to PCM...?

[bubba68ss]

ISS is connected.

Here is the latest tune I have tried.

19174

[Taz]

Take a look at D0910 and D0925 - you have the shift logic backward. Upshift speed must be greater than downshift speed. Your part-throttle shift tables look OK - but only glanced at them, did not look cell by cell.

[bubba68ss]

I see that. Could that be causing all my problems?

I looked at a stock 6.0 4l80e tune from tunedepot and it has the logic reversed as well. http://www.tunefiledepot.com/calibrations/stock/Chevrolet/2002%20Chevrolet%20Silverado%20Truck%20Automatic%2 0LQ4%206.0%20Litre%20(12212156).ctz

[Taz]

Some OEM tunes have the WOT shift logic backward - we as tuners strive to improve upon the OEM tune.

D1206 to D1209 (I think) determine the TPS% when the PCM will use the WOT parameters. If this vehicle shifts OK below about 80% TPS, but then fails to shift property at WOT - then this is likely the problem (or one of the problems). I generally set the last 3 cells of the part-throttle shift speeds to the same value as the WOT speed - for each respective shift.

[joecar]

And the other WOT shift MPH parameters are backwards also (e.g. D0915 and D0930, D0920 and D0935).


The rule is (applies to all MPH shift parameters/tables): downshift MPH must be below the upshift MPH...

this difference in downshift/upshift MPH is called "hysteresis", you want it to be about 5 mph or greater.

[joecar]

Also, set D0960,1,2 Throttle Kickdown to 100% all cells (otherwise these interfere with the PT upshift/downshift tables).

[joecar]

Yep, stock truck files are the worst offenders, it's a wonder they shift...

they are also the worst offenders for PE enabling, I'm shocked at GM.

[bubba68ss]

Which PIDs should I watch that could reveal any potential problems? After I change the up shift and down shift points of course. ISS? OSS? Commanded gear? Anything else?

[bubba68ss]

Just pulled a p0706 trans code. Related?

[Taz]

From memory DTC P0706 relates to the transmission mounted Gear Position (Park-Neutral) Switch used by Trucks and Corvettes.

[bubba68ss]

Does it affect shifting or indicate internal problems? Info not have the range selector in the harness.

[Taz]

If you are not using a transmission mounted Gear Position Switch, then the tune needs to be adjusted accordingly - as the PCM is not receiving these inputs.

When you get your shift speeds sanitized post your tune again. I can turn off the Gear Position Switch for you - I don't think the necessary parameter is available in EFILive.

[bubba68ss]

19178

[Taz]

19178

That is a completely different tune than you originally posted in post #3. This one looks like a Corvette tune (from the TuneFileDepot) with 4L80 segments swapped in. The WOT shift speed logic is still backward.

I have a limited amount of time available to help out on this Forum ... I get a little frustrated when people don't first help themselves by trying everything that they can to make things work ... I'm stepping out of this thread.

[bubba68ss]

I was trying to start over with a 12212156 OS (which I have used a lot before) with DBW and simply uploaded the wrong file by mistake. This was the version I had saved after segment swaps and BEFORE I corrected trans shift points. I apologize.