We rebuilt my 94 lt1 and put a rebuilt 95 trans in it.

The car starts in first, goes to 2nd, and third, but not OD.

When you come to a stop it doesn't go back to first...their is no OD ever in it! Car has a 3500 stall in it.

So you are taking off in 2nd all the time.

we took it to a mechanic he said it is cpu related.

Can you switch out the TCU in these cars and will the fix it?
or are their any ideas on how to fix it?



The second problem is that the car used to shake a little (previous owner loved donuts...)Now that we switched transmissions in it, the car shakes at around 3000-3200 RPMS. Its like wub...wub...wub...wub...wub..which leads me to believe it is the driveshaft and it isnt balanced. Any ideas on how to fix this or could it be something else?

Sidenote - when we dropped the old trans, we had to cut a bolt off of the torque arm cause it was in a bind. So their is the top bolt and one of the bottom bolts hooked up. The other one has about half of a bolt in the hole.

 

get that half a bolt outa there and replace it. have a look here LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums - View Single Post - tranny swap

 

What about that? We already done the staking, well, actually, we didn't have to cause the trans has a shift kit in it.

Their is nothing mechanical in the trans stopping it from working. It has to be on the harness or the PCM that stops it. The guy we took it to said he cleared the cpu and drove it and it worked fine...once the pcm picked up on it...it went into limp mode.

 

ok change the pcm. did you read the info in the link. the 95 has one more pin than the 94 and requires a mod to work right. other than that it should work. have you adjusted the shift cable?

 

CPU is in your PC. PCM controls your trans shift points. The PCM replaced the ECM in 1994 and the ECM replace the ECU from the 80's computers system. If your system is going into Limp home mode that that needs fixed but even in LHM as long as the speed sensor reads zero the transmission should be in first gear.

FYI
ECM=Engine Control Module. This controls your EFI and Ignition and over sees some other modules (pre-1994)
PCM=Powertrain Control Module. This controls your EFI, Ignition and transmission and over sees some other modules (1994 and up)
PCM is what goes into LHM and it is what controls your transmission.

Even with the TCC plug disconnected the trans should go into first gear with the speed sensor is reading zero. It will set a light but the trans should work. Heck I am pretty sure that if you do not connect anything to the trans and you put into drive you get first gear. It would not shift into to second without the PCM connected but I thought 1st gear was the default. I never tried it but just assumed it.

Issues with the drive shaft should be based on the cars speed not RPMs. If the car shakes at a given speed it is a driveshaft issue but if it at a given RPM then the issue is before the transmission. If it is truly a balance issues you can put the car in neutral and turn the motor off and still feel it. Under load can make the shaking worse but you should still be able to feel it without the motor running at the given speed.

 

No, we havent adjusted the shift cable. How would we do that?

And we done mod A method 2 (staking the PWM). We didn't have to stake it because the Shift Kit the trans has eliminates the PWM. and if it doesnt...we staked it open anyways.

This trans does the exact same thing as the one we dropped. Starts out with 1,2,3, not OD. Once it goes out of first, you don't go back to 1st...leaving me with 2,3 rd only.

 

Once it shifts out of first, it will NOT go back into first unless you cut the car off and let it sit for awhile. Their has GOT to be a burnt/crushed with somewhere...the odds of getting 2 transmissions with the same exact problems is highly unlikely.

I am thinking maybe the motor mount bolts are a tad lose? maybe the trans bolts.

So I plan on putting the car back on ramps and tightening the crap out of all the important bolts and replacing the torque arm bracket.

 

Adjust A4 Trans Linkage

 

This part throws me off. Last I checked, the trans isn't supposed to shift back down to first, unless you manually select it. It's supposed to stay in the gear it's currently in so long as you're not flooring it, then it's supposed to kickdown.

But you are also saying that it's not kicking into OD. What exactly is leading you to think this? Not feeling the shift or your RPM's?

 

Its supposed to go back to first when youre at a stop sign. It doesn't kickdown either.
When its in third gear in D you put it in OD and it doesn't change at all. When its in OD it sounds exactly the same as D, when you put it in D the car has no change to it at all either. Then old trans lost OD also, and done the same thing with 1st, thats why we replaced them.

We hooked a scanner up an no codes were being thrown.