my hypertech chip did the trans too, it raised the shift points and disables the performance/normal mod in the trans , so it stays in the same mode all the time. the shiftplus made the trans hit harder into gear. you can make one too. it is just a controlled vac leak that is "T" ed off the vac line going to the modulator valve in the trans.
Got it at the Grand Prix Store - PFYC
The roads finally dried out yesterday so I experimented with different settings.
All it seems to do is tighten up the shifts. The instructions say that it raises the line pressure from stock settings by 10 to 30 psi depending on the adjustment dial.
In the 4T65-E trani, as the Pressure Control Solenoid Valve Current changes from 1.1 amps to 0 amps, the Line Pressure rises from 50 psi to 230 psi.
In my Service Manual it says that the line pressure can be +/- 40 psi for each corresponding current input, so 30 psi more doesn't seem to be relatively excessive.
It really does firm up both the upshifting and the downshifting.
I started out with a mid point setting. Not bad. During acceleration from a stop it is more firm as it shifts into second. If you're cruising and stomp on it, it downshifts with authority. If you manually drop down to 2nd, there is a pronouned shudder as it downshifts. You can really feel the slop caused by engine movement and all that soft rubber the factory uses to luxo out the ride smoothness.
I next moved it to minimum setting which was less dramatic and not as noticeable firmness.
Then I tried the max setting. It did not bang screech. It did grab the next gear much more firmly but it feels like there is more softness in the rest of the drivetrain that absorbs the impact before allowing the tires to lose traction. I drove over a wet patch and tried it and the tires did spin when shifting into 2nd gear.
I settled on midway between middle and max.....for now.
The reason I invested in this device is more for transmission duribility by minimizing clutch slippage and heat build-up rather than acceleration improvement but it seems to give it a little better driveability snap.
Some people may find the harshness of downshifting a little annoying, particularly at the max setting.
I'll be interested to find out how this module works in conjunction with the upcoming Jet Chip Module.
The Jet Chip is supposed to change shift points and eliminate limiters like that annoying 3rd gear 4000 rpm limitation.
The good news is that it didn't set off any codes.