0411 Transmission Flaring - Tuning or Trans issue

[evilstuie]

Hey all,
I'm heading to the dyno in 2 weeks to get my project car tuned, its a SBC406 with AFR heads, HSR EFI intake, EX276HR cam, with a 0411PCM running it all with a stock 1997 4L60E, stock converter and 2.73 diff.

The tune LRT helped me with has been fantastic for idle and driving it around, there's a weird issue with a temporary bog-down and backfire spot, but that's not my issue.
My issue is when it is working nice, I'll put the foot down and the engine will rev great, but the transmission is flaring and not putting power to the back wheels.

I'm not sure what the transmission calibration is that was swapped in, but I'm wondering if there transmission calibration is for something meant to be a lot softer or slower changes etc, if someone can take a look.

The other issues I have that might/maybe affect it are:
* Possible vacuum leak causing the brakes to not work that great (could also be the issue with the backfire/bog down issue)
* Fuel sounds like it boiling back in the tank. After 20 minute drive the fuel is just bloating in the tank and you can hear it hissing and bubbling

Trans fluid is at correct level, there's no leaks or anything, and all gear changes are working and fast into gear at idle.

I just need to know if it's possibly a tuning issue or a problem with the trans before I lay out $1000 for a day of tuning to find the power won't transfer and they cant tune the engine under load.

[lionelhutz]

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.

[evilstuie]

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.

I haven't got a line pressure gauge so haven't checked that yet.

[lionelhutz]

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.

[Hog]

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

[lionelhutz]

Yes, but adaptive shift is not torque management. Adaptive shift adjusts the line pressure during the shift.

[LRT]

....

[buddrow]

If you are running MAF, make sure it isnt contaiminated. Trans gets primary load information from MAF, if that data is skewed, youre screwed.

[lionelhutz]

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.