OBDII and 3100 Virgin. Help with shift points, etc

[Steve Pickering]

OK, I am new to these engines and tranny’s. I have an 1988 Fiero. 1996 3100 with the 96 4 speed 4T60E Auto and OBDII.

The problem is when I take off it acts like it is waiting to shift into low or passing gear. When I count the shifts at a steady speed, there are four. This feels like a turbo boost hesitation (No it isn’t turbo charged). If I stand on it from the start it red lines before shifting. But if I just step down reasonably (as if there was such a thing) it starts off pretty mild and then suddenly develops tons of horse power and takes off like a raped ape. I want to take it to the track in a couple of weeks and I have noticed if I start it in first and shift right after taking off that is when it red lines in all gears before shifting.

Now I am no mechanic (well fair shade tree), but I know nothing about these. I suspect the OBDII controls things like the shift points and pressures, and a reprogram could be the answer. You guys have all the answers so you tell me. What all does the ECU control and how much is changeable? (PS I like my current fuel mileage)

[robertisaar]

you'll need a DHP to tune the 96 PCM, or if you jump to a 97 PCM, you can use either a DHP or HPT setup.

[pocket-rocket]

I can confirm that your ECM does control the transmission. The "E" in 4T60-E means it's electrnically controlled by the ECM. You can change shift points, but as for pressure the 4T60-E has a vacuum modulator. I've read you CAN buy an adjustable one and have control of that by way of a set screw in the vacuum port on it. You will need something like an HPTuners setup, or DHP. HPT is salty, but still produced. DHP has been gone for a while, but units are still floating around and there is still a good support base via other wrench heads for it. The main thing is from what I read, HPT can't tune a 96 ECM while HPT can, but I believe you can change to a 97 ECM without any problem at all. That's pretty much what I can offer up as far as information. There are others that are well more versed in OBD2 that can help you more on this board.

EDIT: Ninja'd by Robert. See? lol.

[Steve Pickering]

Ah....... OK... I think?

[RedZMonte]

well if the engine, trans, ecu are all from the same car then it should be all stock. You should not have these problems with a stock ecu, trans, engine. i don't think the problem is in the tune. sounds like its a mechanical problem... If the ECU is for a different car then the trans is from, then it could be a issue of tuning... But shift pressure is done via the vac module.... The shift points should all be fine stock. I would look at the trans... (Tq converter, new filter and fluid, ect...)

what is the ECU, Trans out of?

S