ls3 turbo 600whp with 6l80 with trans issue...help needed..

[Robert Rejholt]

Hello, I resently bought a used and bulit 6l80, it also included a "2500rpm" stall converter.
It was bulit sometime ago... 2010 it says.
It was built with best the parts that was avalible back then and they even bougt a tune for it from "someone" in US.

Back then it worked just fine on a c6 procharger with about the same or even more hp. think they ran high 9 on 1/4mile.

My problem now is as followed:

when going low/part trottle it sometimes (but not always) slips when going 2-3rd, the more I acc the better it gets.
So I dont think/hope it the tran itself.
I`ve tried some diffrent settings with bluecat trans calc, but the problem only changes to the 3-4th gear.
If I go full trottle it works much better.
Big problem is that I can`t fint anyone back here in sweden who knows this trans:-(
Oil level is correct, can trying overfilling it with a quater help this problem?

I guess it would be god to make a log in the scanner, but not sure what exactly to log? please ca someone explain how to, newbe with hpt and the scanner.

Any ideas are welcome. A big race coming up in a couple of weeks, it`s almost like dragweek but it`s called streetweek here.

[email protected]

You can also have a look at my CamaRRo at facebook #RRacingsweden if you like, it`s a all true "home made" car with fiberglass body on a tubechassie, ls3 e85 turbo.
Thanx in advance:-)

[Robert Rejholt]

updated with my file.... hope someone can help me.-)

[5FDP]

Surprised you aren't even running a 3 bar MAP sensor so you can tune the computer for boost or even log boost for that matter.

Often times if the engine side airflow model is not spot on it can cause the transmission to do weird things. Making sure that is dialed is key.

For the time being I would honestly try to revert back to some stock settings with the transmission. Compare with a stock file to see what torque mngt settings were disabled or changed and go back to stock.

From there I would be looking at some of your pressure settings. You may want to slightly increase the shift pressure for the 2-3 shift at lower torque values. Do small changes at a time. Also the on-coming pressure presets. Try raising them for the 2-3 shift by like 5% at a time.

Doing pressure changes will require you to reset the adapts using the VCM scanner. You need to flash your new tune file in, then go to the VCM scanner > special functions/vehicle controls > transmission. Then click trans adapt reset, then click preset and start the car. It will take a few times through the gears to relearn and adjust to the changes.

[njedwardz]

Firstly, as mentioned here, reset your shift adapts. That will get rid of your slip, at least temporarily.

Second, to permanently solve the issue, you need to adjust the torque model in the engine tune to match what the car actually makes. The ECM tells the TCM how much torque is being delivered at any given time, so when it is time for a shift to take place, the TCM will request timing cut, pressures, shift time, etc. to match that torque value. If the reported value is way off, you'll notice very sloppy part-throttle shifts (often not much at full throttle since that will command a full scale shift event anyway). This does take a lot of time to get right but the HPT virtual torque tool can be very very helpful.

There is also something weird with most cars' 2-3 shift volume adapt setting in the tune; I don't remember what the right value to set it to is so I won't say in case I get it wrong - that can make a big difference as well.

[Robert Rejholt]

Thanx for your advise guys, been buissy rebuilding the trans .........
The trans is back in car now again, and I will start working on the tune in a couple of hours:-)
first test drive late night yesterday= works great att full throttle, weird shifts att part/low throttle....