I'm working on a 1988 Trans am, Its a 305 TBI car with a 700R4.
What i know: When the car is in park and you start the engine the entire car leaps forward for a split second but doesn't go anywhere, put the car in any gear the car dies but now with the rear end suspended on jack stands with the tires off the ground when the car is in park when the engines running the tires spin at a consistent speed, selecting forward and reverse gears is fine when the cars rear end is suspended however when applying the brake when in forward or reverse gear the car bogs down and when more brake pressure is applied the car dies instantaneously. I have hooked up to the ALDL and i have flagged data (I'm using WinALDL as my logger) In the flagged data the boxes checked are: p/s pressure switch, No high gear, Park/Neutral, Old high gear.
I'm not as knowledgeable when it comes to automatic transmissions so any help would be appreciated!

 

Sounds like the torque converter clutch is applied when it shouldn't be.

 

Anyway to test or fix this?

 

700R4 works or they don't, when they don't, it cost money.

There is never any inbetween with them. Drop a grand on a new one.

 

Pull the elec plug out of the drv side of trans and see if it still happens
However if the trans is functioning correctly and the convertor was locked it should only stall the engine when in gear ( on the ground )

 

+1.


Kinda' sounds like the lock-up is always engaged.

 

The pawl inside transmission should engage when the transmission is in park preventing the rear wheels from turning.

I think this transmission has more than a few issues going on.

 

I looked into it more today, 1st the cable is broke and you can move it in gear by hand under the car. 2nd the MAP sensor was connected to a one way check valve and was consistently under MAX vacuum i think this was part of the why it would die in gear... I push the tranny in park by hand, started the car, no tire spin. I'm going to order up a new cable and see what happens in the other gears.