4L80E, Tuning Help

[Buick Motorsports]

Hey Guys,

Got reacquainted with a fellow gearhead tonight. He tells me that he's put a 4L80E in the car. He cannot get the tune right and there seems to be no one here who can help him and the TCI help line didn't pan out for him( I didn't ask for the details.

I told him that I would ask the collective knowledge of Lateral-g for help.

Here is the specs:

1956 Chevy
502 (500 - 550hp @ crank ) naturally aspirated
4:56 gears
4L80E is stock gearing, the tranny shop put in a "stage 2 shift kit"
TCI computer and harness

All he wants is a factory tune that will behave predictably. Here are 2 symptoms of the tune:

- when he gets on the throttle, the trans will not shift unless he lifts the throttle.

- when he is rolling @ 5 - 8 mph, and he ratchets down to first gear, the car almost comes to a complete stop. He says it feels like its going to throw him through the window.

Those are the basics, hope that you Guys can maybe give us a hand.

Thanks.

[ElkyZO6]

Originally Posted by Buick Motorsports

Hey Guys,

Got reacquainted with a fellow gearhead tonight. He tells me that he's put a 4L80E in the car. He cannot get the tune right and there seems to be no one here who can help him and the TCI help line didn't pan out for him( I didn't ask for the details.

I told him that I would ask the collective knowledge of Lateral-g for help.

Here is the specs:

1956 Chevy
502 (500 - 550hp @ crank ) naturally aspirated
4:56 gears
4L80E is stock gearing, the tranny shop put in a "stage 2 shift kit"
TCI computer and harness

All he wants is a factory tune that will behave predictably. Here are 2 symptoms of the tune:

- when he gets on the throttle, the trans will not shift unless he lifts the throttle.

- when he is rolling @ 5 - 8 mph, and he ratchets down to first gear, the car almost comes to a complete stop. He says it feels like its going to throw him through the window.

Those are the basics, hope that you Guys can maybe give us a hand.

Thanks.

Sounds like a solenoid in the valve body is acting up.

As far as the ratcheting down to first while rolling, at sounds like there is something wrong in the trans. Was the trans rebuild or just had a shift kit put in? The 4l80e shift kits I've seen require some pretty good mods to the valve body. Just my 2 cents.

[Buick Motorsports]

It was a rebuild as well. These are the kind of things that will help us trouble shoot.

[ivmotor]

The 2-1 downshift involves a drum rotation reversal. It will be a very abrupt shock to the tires. I usually won't drop mine into first unless I'm stopped or under throttle.

I've done quite a few tci tunes, try opening a new tune file and making sure the vss is right or at least working consistently. The shift tables are time consuming to set and its usually easier to set from low to high than the other way around. If you want email me one of the tuning files, I'll compare it to some of the files I have here.