Fishnchipy

I have a 1997 Cavalier Z24 with a 2.4L engine and a 4 speed auto (4T40E). The issue I am having is it wants to shift from 3rd to 4th immediately and the torque converter will not unlock at freeway speeds. 1st to 2nd no problem but 2nd to 3rd then immediately into 4th. The other thing is when under a load like climbing a hill it will not down shift and the TCC will not unlock. This sets the CIL to a P0742 code. I installed all new solenoids and pressure manifold when I installed this transmission. I have checked the resistance and checked for shorts in the harness. All fall within specs and no short to ground.


If I tap the brakes while rolling down the road the TCC unlocks then locks back up so I know its not stuck on as the code indicates. When the CIL comes on, the transmission goes into limp mode and short shifts 1st to 2nd and 2nd to 3rd. If I manually shift the transmission it runs just fine. I then erase the code and it goes back to how it was with a quick 3rd to 4th.


Now what I have noticed today was while climbing the hill I let off the gas then accelerate and the transmission will down shift into 3rd like it should. If I slowly accelerate up the hill it will hold in 4th and trip the light. If I accelerate hard it will skip 3rd and go into 2nd and tach out. I have replaced the TPS with a Pepboys special. I am wondering if this is the cause. I have swapped out ECMs already and no change. I strongly feel this is an electrical issue and not a transmission problem since as I stated before if I manually shift the transmission it runs like a champ.


Does anyone have prior experience with something like this? Am I leaning in the right direction? I was told by he local transmission shop the torque converter was what was bad so I replaced that this past weekend and no change. That's a ton of work for nothing! Help me please!!!!!


MIKE