New here and have a problem :P

[Jgra]

Ok heres the problem.
I recently got a 95' grand am that had a horrible 3100 engine ( it had around 250k miles on it and it was just bad... ) so I decided I'd switch it out with a 91' Corsica's 3.1 which only had around 30k miles on it. Decided to go ahead and switch the transmission as well, which really wasnt a choice because the block wasnt quiet the same.


Well everything is in and running great except the transmission (automatic) wont switch gears while driving, it goes into 1st and doesnt progress. Can anyone give any insight as to why? We have both books and matched up the wires as best we could and cant seem to figure out wtf is goin on

Also, I'm not really the most car knowing person so I have no clue what the names of the transmissions are but both of them had "hydro" something :P and the Corsica's said Hydro something turbo if that lil bit of info helps.

Thx for any advise you guys can offer

[Jgra]

Ok, update on the info I have on the problem:

The former engine was a stock 95' grand am 3100 SFI engine w/ 4T60 transmission. What we put in was a stock 91' corsica 3.1L MPFI engine w/ TH125 aka 3T40.

Like I said I'm not the best car person, I asked around and I was told I probably need to take the corsica's computer and put it in the grand am. Because pretty much everything under the hood is now from the corsica :P

Is there any advice anyone can offer other than switching computers, and if I do have to switch computers, how hard would that be.

[bszopi]

My advice... If you have the old tranny, put it in. It will bolt up just fine. There are ALOT of differences between the 3T40 and the 4T60E (yes, you had the electronic version), and I find it hard to believe you managed to match up any wires between the 2. Could you get around it? Possibly. But if the old tranny was fine, you are better off just using it.

[Jgra]

Yea we kinda jury rigged alot...

The old one is fine but it didnt look like it would bolt in the same, gonna have to try tho I guess

[86euro]

Geez, you did the complete opposite of what anyone else would would do, lol.

[gpse3400]

Do you have your TV cable connected and adjusted??

[Chris88CL]

Yikes. Where to start?

The 4t60-e is computer controlled. The 3t40 isnt. The TV cable should just kick down the transmission into a lower gear. It shouldnt prevent it from upshifting normally like it should. Do you have all the vacuum lines hooked up to the transmission?

Are you sure the transmission worked properly prior to you installing it in your car?

Without knowing how you rigged everything up it's tough to tell you if you can just switch computers and have everything work properly. I've never heard of a 3.1L MPFI engine running SFI unless it was a 3100.

Honestly, I would drop the 4t60-e back in with the 3100 top end on the 3.1L block and be done with it. It will run as a 3100 minus the cam differences and you will have completely fresh gaskets and a transmission and wiring that doesnt have to change.

[sharkey]

the 3t40 (th125) has no vacume modulator. the throttle cable to the tranny must be hooked up and adjuster close to correct or if wont shift. it has a failsafe linkage in the tranny that if the cable was to break or be unhooked, it puts it at aprox 1/2 throttle pressure to prevent it from burning up, and it will only shift around 4500 rpm.

my best advice is to put the 4t60e back in. the pcm is going to run in limp mode as it doesnt detect the tranny there.

[TazMan]

Honestly, I would drop the 4t60-e back in with the 3100 top end on the 3.1L block and be done with it. It will run as a 3100 minus the cam differences and you will have completely fresh gaskets and a transmission and wiring that doesnt have to change.

If you do, don't forget to get custom length pushrods.

[86euro]

I had a 125 do that... it was cooked. The fluid that came out was dark brown metallic.

[3400-95-Modified]

I don't even know how you have a MPFI motor running on a 3100 ecm... your missing the cam sensor and 24x crank sensor...

That driveline swap was a VERY bad idea since the 3.1 is such a slug in comparison to a newer 3100 or 3400.