pcmhacking.net

Hi guys need some help with tunning the 4l60e in my vx v6 box is stock and just won't change gear any advice on what to do in gearbox setting to try and help it will change when I back off but won't change at wot is there anywhere that I can change that will bump up line presser and is there away to retard timming on change car is turboed running low boost around 13psi but would like to turn it up but I'm still learning a lot about tunning motor is dead stock 1000cc injectors 380lph pump trans stock with large trans cooler new filter and oil am I better off dropping the pan and giving the torx screw a half a turn can't rembere what it's called car is heavy it's a wh statesman

Is the PCM actually commanding a gear change?

Try lowering the gear change speed at WOT and see what that does.

90psi is 100% line pressure in the tune. The only way to increase line pressure above that is mechanically. Ideally you'd fit a larger boost valve

https://www.alltranz.co.nz/shop/drivetr ... duct/6628/

And corvette servo to apply more pressure to the band (2nd gear).

https://www.alltranz.co.nz/shop/drivetr ... uct/19023/

I believe Holden202 has more tuning tricks to help these auto's live at higher power settings so maybe he can chime in here.

You don't want to increase the low rpm, low tps line pressure too much as it will make normal driving terrible. There is a table called Power Enrichment PSI Offset Vs RPM so use that to increase line pressure when on boost at low rpm when you should be in PE mode.

Also, you don't want to add to much boost with stock ring gaps, if you do and get things too hot the rings will butt up and lift a ring land and then you'll be up for a engine rebuild.

Thanks immortality have ordered a few parts for the gearbox .500 boost vavle a corvette servo but I live in the middle of know where so parts take a while to get here

So these are the mods I have done to line pressure hoping it will improve the gearbox shifting can anyone see any issues before I take for test drive tomorrow

OK guys it's stopped the gearbox from slipping and now will change under full boost pretty happy with how it's going just going to make shift time a bit quicker down to 1sec see how it feels