I have a 1992 bmw 735i that I put in an engine and transmission from a 1989...

I have a 1992 bmw 735i that I put in an engine and transmission from a 1989 735IL and now it won't shift until really odd points and the only way to get it into what is either 3rd or 4th is by getting it to 6000 rpm and then it slams into it EDIT: NO FAULT NOTIFICATIONS , I replaced the TCM already and it still does it!!! please help!

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  • Was is working fine in the donor car?

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  • yea worked fine in the donor car no issues with shifting or anything trans related all it had was a slightly rough idle and a bad instrument cluster

  • Maybe transmission loom is different in the 1992 car vs 1989?

    It runs from shifter to trans and to the trans ecu in the a pillar on right

  • the TCMs are the exact same so I find that odd that it would be different but for the mode selector switch instead of 9 pin holes there was only 8 but that only selects the mode?

  • so it could be? but would that really cause erratic shifting?

  • I would at least have the exact same setup before anything else

  • 7pin/8pin transmission mismatch?

  • Rumour has it the 89 and the 91 onwards have different gearboxes coding even though they maybe 4hp22 that may be your problem

  • My bet is the 7/8 pin set up as well. I also presume the new and old box's were both switchable? You can use a 8 pin box in a 7 pin car and visa versa, just swap in the loom and gearbox ecu that goes with the box

  • Boxes? Assuming gear box?

  • Omg i think you're right

  • How would i replace that?

  • The 4hp22 for the e30s have a kick down cable when over tightened they have this issue

    I dont know enough about the e32 to say this is the issue they may have replaced it with some sort of hydraulic or solinoid or servo mechanism, probably electronically controlled my guess if i were to take one would be that extra wire is the feed for some sort of solinoid which controlls shifting via kickdown

  • The older 4hp22 in e32 had a kick down cable. Only like 1987/88 models of 730s ive seen with it.

    And then there is the later 4hp22 which didnt have a kick down cable, but a switch with S-E-M. The newer one i refer to as 4hp22-eh, more electrical than the older hydraulic one.

  • The one i pulled from the 88 had the sem switch so no kick down cable? And what would be the cause in that? The 8,7 pin difference or?

  • They are to my knowledge not interchangable

  • How do i replace it? Any guide?

  • When I replaced the trans in my '92 750il, I remember there was a year break there....I believe '91, as was said.....I have a complete '88 750il parts car that had an engine fire, and could not use the one from that car. Punch it in on car-part.com.....that's how I found it wouldn't interchange, I'll bet thats your problem...

  • I'm kinda lost what exactly is the part im needing to replace im still learning cars I can replace things but when it comes to technicals im behind the curve

  • Well, you have a transmission that is incompatible with the car it was installed in.....don't know of a cheap or easy fix for that. As I said, I'm not certain exactly what the difference is, but there IS A difference....thru 12/91, or from 1/92 is the year break for the transmission, so I'd expect there is some internal difference, whether it be electronic, mechanical, or both....

  • I swapped engine trans and all electronics so I'm assuming harness or some connector

  • If you still have the parts car it might be ideal to swap the computer and driving components and see if that makes a difference

  • Have the parts car i have harness and computers but I swapped tcm and no change

  • Didn't get home until late today so tomorrow I'm going to climb under both and check out the harness since I gta jack the car up to test fit wheels also

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  • Could it be because it is way overfilled with fluid according to the stick it's massively over filled