94 e36 6cyl WITH 98 TRANNY w/PROBLEMS after only a month once installed

[bmwbeemer77]

I have a 94 325ic 6cyl and I installed a working tranny from my sons wrecked 98 328ic and the car drove perfectly fine for over a month every single day. then all of a sudden it would not shift properly. It seems to be in limp mode. It would miss 1st and 2nd. I changed the fluid and filter but still not change. Did I maybe do something wrong? Any help would be great. I haven't been able to drive the car in over a year. I've owned my 94 vert since 1994 and I love the car. One thing I did notice was the main plug on the tranny where the harness connects had a different connection. I used my connection from the broken 94 tranny and soldered it on the 98 and it worked. But just like I said, the car drove perfectly fine without any issues until about a month or so later. Then I haven't been able to figure it out since. Did I do something wrong? I checked compatibility with REALOEM before I even attempted the install. Also, What about the fluid? I put the same fluid in the trans as I used in the 94 model. My older son has a 2003 325ci and it uses a different fluid. So since the tranny I installed is 4 years newer, would that make a difference? Like I said, I love the car

[pbonsalb]

Is this an auto or manual?

[66 6]

I would try installing the auto brain (ECU) from the 98 into your car. It's located above the engine ECU on the passenger side fire wall. The 98 and 94 used different transmissions and auto ECUs may be specific to the tranny.

[bmwbeemer77]

I'm sorry, it is an automatic. Also, I thought about installing the tranny ecu but the plug on the 98 ecu is totally different than the one on the 1994 car. It's just weird that I was able to change the actual adapter where the electrical connection on the tranny under the car. Like I said, all the wires have the exact same colors as the 94 tranny so I just separated the wires from the 94 tranny and attached it to the 98. I do still have the ecu for the 98 tranny. Also, it' that GM transmission(umph) lol

[66 6]

Also, it' that GM transmission(umph) lol

French made GM tranny. Not sure it could get any worse

[scooper]

I've swapped a 94 auto trans into our 96 328, and there were no issues. I didn't have to swap the auto computers nor did I have to do any splicing. OP what fluid did you use? Did you clean the magnet and have you checked fluid levels the proper way recently?

[bmwbeemer77]

Yes, I did clean the magnet and I verified the fluid and levels several times. The 97 and 98 trannys are have a different connection at the trans. The 96 is the same as the 94. I'm gonna get back at it this weekend as I was stuck on my sons 00 mustang he just bought. It's gotta be something electrical.