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58 Posts
Discussion Starter · #1 ·
I might have to go to the LT1 Edit mailing list for this, but I'm going to try it here anyway.

I just recently installed an Edge 3000 RPM stall and a rebuild trans with a Pro-Built Automatics Pro-Street rebuild kit.

Since installing the converter and trans, I have noticed that if I turn off TCS, and stomp the pedal from a stop, the car will spin 1st, shift to 2nd (seems to be early really), then back to 1st, and finally back to second. This does not happen instanenously or anything, but that's the pattern that it exhibits.

Now, I'm using LT1 Edit.

If I look at the Automatic transmission settings, I see this:

KickDown Mode
Normal Shift RPM:
1-2: 5344
2-3: 5440
3-4: 5344

Hot Shift RPM settings are same as above.

WOT Shift MPH:
1-2: 34
2-3: 70
3-4: 120

2-1: 30
3-2: 64
4-3: 113

Hot shift MPH settings are same as above.

In the Normal Mode Shift vs TPS in MPH, the 100% settings are the same as above as well.

Does anyone here know the rule the PCM follows for shifting?

Is it checking for a single condition to be met, or do multiple conditions have to be met?

58 Posts
Discussion Starter · #3 ·
I was going to ask you if you would email me one of the later tunes you ran, after installing the 3.73s so I could see the differences.

I have one of your tunes from a couple years ago when you still had the 3.23's, and have been looking at it for ideas.

58 Posts
Discussion Starter · #6 ·
Think I got it solved tonight.

I tried replacing the vacuum line for the trans, but that didn't help.

So to I tried different shift points.

I had been running a Madwolf tune, with his shift points for a 3.42 car.

Tonight, I loaded my stock 2.73 file, converted the shifting for 3.42s and copied that table to the Madwolf tune.

The 1-2 shift is now set at 38 MPH, and the 2-1 downshift at 23 MPH, that's a 15 MPH difference instead of the 4 MPH shown above.

Loaded the file to the car, and went driving.

Got to a place where I was alone, turned off TCS and nailed the throttle. The tires spun all the way through first, and part way through 2nd. No downshift.

Before, the car would spin the tires, then hit 2nd and immediately stop spinning, then downshift, then upshift and bark them hitting 2nd the 2nd time.

What I think was happening is that the tires would start spinning, wheel speed would come up above 34 MPH, when it hit 2nd, the wheel speed would drop some, below 30 MPH and the car would go back to 1st, then when it hit 34 again, it would go back to 2nd.
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