ECU help...Automatic vs 5-speed difference?

[Fooshe]

If one was to convert an auto transmission car into a 5 speed car, do you need to change the ECU? What about the wiring harness? If the answer is yes to either, why is it necessary?

Please, no guesses. I need solid facts. I have run into a problem that I don't understand and can't figure it out. Thanks in advance for the help.

[mr.vang]

Automatic and manual ecu are the same. I don't know about wiring harness though

[Fooshe]

Thanks Mr. Vang.

What puzzles me is how they can be. Doesn't the chip look at the shift points? If so, it would be different for an automatic and a stick....right?

So the next question I would have is this:
IF the ECU's are the same, do you need to change the chip out on the 173's ECU for the automatic and use the chip from a stick?

[reelizmpro]

I see no distinction between auto/manual on E30 DME's. Just tell us your problem.

[Fooshe]

Ok, that probably would help.

The car is an auto to 5 speed conversion. The car currently has a 173 ECU with a Dinan chip it in. If I plug in a regular 173 ECU with a stock chip, the car won't run. I should mention, the wiring harness is not stock. It is from a 525 that used the M20 engine.

[mr.vang]

Have you test the ecu on another car? It may be a bad ecu.

[mr.vang]

Btw, I'm running an automatic 173 ecu on my manual 325is.

[Fooshe]

Yes. Both ECU's worked before the swap.

The car with the harness ran fine with the ECU with the dinan chip. Just want to use a non-chipped ECU. If the ECU's are the same, a chip swap alone would work....I would think.

[reelizmpro]

Sounds like you need to do more troubleshooting. I just double checked and the 173 is identical between the E30 and E34 M20 models.

[MR 325]

There's absolutely no difference between auto and manual ECU or harness.

If your ECU with stock chip isn't working either the chip is backwards or the ECU is bad.

[Fooshe]

Figured it out. The car will run with either ECU, but mine would not even start. The difference is the neutral position switch that the auto trans car does not have.

[reelizmpro]

I'm lost. The auto trans car does have it but you need to bypass it if you do a 5 speed conversion otherwise it won't start. In Automatics, you need to be in Park before you can start the car. So are you saying you forgot to bypass it?