Can you post the tune to look at?
How's the part throttle shifting? Good part throttle but WOT could mean the line pressure isn't high enough at WOT.
Did you put a line pressure gauge on it? I suspect you have to modify at the shift pressure or force motor tables but without a gauge you're just guessing.
Here's the tune file.Originally Posted by lionelhutz
I haven't got a line pressure gauge so haven't checked that yet.
I was hoping to check the force motor current tables but they don't seem to be in the xdf.
When it is flaring? Just slips when driving?
If it's a shift flare then I would go after that shift pressure table first. You should be able to take it up to at least 90 and possibly to 96. 90 or 96 would give you the most line pressure possible without modifying the force motor current tables. Log the motor torque and see where you're torque wise during the shift. Then increase the table in that area. I expect it needs to be ramped up quicker to 90 or 96 as the final value. It also needs to plateau for the highest torque part of the table.
Also, drop at leas the 3-4 shift times to 0, possibly lower the other shift times as well and see how that helps.
Is it an actual flare, which is where the engine rpm increase during the shift, above the rpm at which the shift was initiated?
or
Is it a shift "bog", rpm drops properly during the shift, but the perception of an excessive decease in forward acceleration is evident.
If it is a "bog" and you are using an L31 calibration as a base in the 0411 PCM, the Torque Management could be an issue. The amount of Spark Advance removed is quite large, even more than in the newer 1999+ LM7 5.3 calibrations. IN stock type inductions/engines it can be especially noticeable at part throttle and downright annoying in modified configurations.
Doesn't entering "0" for shit times essentially eliminate the Adaptive Shifting strategies?
peace
Hog
Yes, but adaptive shift is not torque management. Adaptive shift adjusts the line pressure during the shift.
I didn't suggest that disabling Adaptive Shifts was the same as TM
You recommended zeroing out the Shift Times, I'm assuming for diagnostics, and was attempting to follow your logic, which makes could help if its a shift flare..
Thanks
peace
Hog
....
Last edited by LRT; 05-24-2021 at 11:27 PM.
If you are running MAF, make sure it isnt contaiminated. Trans gets primary load information from MAF, if that data is skewed, youre screwed.
If it don't fit force it, if it don't force fit f&%@ it!
Yes, increases in transmission pressure can be accomplished by tuning other tables, but only up to the pressure possible due to the lowest current in the force motor current table. So, altering the force motor tables can allow you to reach a higher maximum line pressure.
I posted to take the 3-4 shift to 0 and lower the time for the other gears.
The transmission tune still looks off, even without considering the torque calculation being off. Shifting 472 ft-lbs at 66% of full line pressure makes no sense. Just to compare, older PCM's for 300-350 ft-lb engines would pass that level at around 25% throttle at low speeds and 50-60% throttle at higher speeds.
At the dyno, they should be able to force the line pressure high so it won't slip and they can do the tuning. Then, either them or you can go back and do the transmission.
....
Last edited by LRT; 05-24-2021 at 11:27 PM.
#1. The transmission line pressure doesn't go from 0 to 96 psi. It goes from about 60 to 180 psi.
#2. The force motor current tables typically do not go down to 0A.
#3. Picking 96 "psi" in the tune tells the PCM to use the lowest force motor current, which is not 0A. So, lowering the table closer to 0A can increase the maximum line pressure.
#4. Suggesting to use a shift kit as the way to modify the line pressure makes little sense, because modifying the line pressure response to the force motor current really doesn't do anything different than ramping the currents in the table down to a lower final value to get a higher line pressure, until you do reach the limit of 0A.
The "psi" in the tune is just a number. The PCM uses the tables to pick a value from 0 to 96, and then goes to the force motor table and gets the current to apply to the force motor. So, the force motor current sets the actual line pressure.
I was just in a Canyon tune with a 3L 4-banger and the 3-4 shift pressure was 90 "psi" across the board and the shift times were all 0. The lowest force motor current was 100mA. So, suggesting the force motor currents could be lowered a bit or to use 0 time for the 3-4 shift just isn't that shocking...
Last edited by lionelhutz; 10-05-2017 at 06:18 AM.
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