M50 E30 Swap, wont start need help!

[David1665]

Hey guys, so I just finished swapping in a non vanos m50b25 from a automatic 1992 525i into my 1991 318is e30.

I can not get it to start and i need help!

Cam and crank sensors are good.
All relays are on from running m42 car so they should be good.
ECU came from a running car (403 ecu)

I used this wiring diagram:

http://www.e30zone.net/e30zonewiki/index.php/M5x_Looms#M50B25

I looked through ecms and I think it is right? Im really thinking the wiring is the issue so if anyone has a pinout for a 1991 318is too an m50 that would be greatly appreciated!


Car turns over but has no spark, smells like injectors are firing.


Some concerns I had were the neutral safety switch and the fact the engine is auto so maybe theres some sort of bypass? Sounds like others dont have any issues with this stuff preventing the car from starting.

What sensors prevent this car from starting? Maybe something is switched around but it seems right.

Thanks in advance!!

https://scontent-b-sea.xx.fbcdn.net/hphotos-xap1/t1.0-9/10484529_10154322266320302_7816570262827643643_n.jpg

[sweet3]

I have recently just done a swap myself. I'm still in the finishing stages actually.
But it sounds like I had the same issue as you. Mine turned out that I bought a bad ecu. The PO told me that everything worked. He totaled his car so I assumed everything worked. When I was having a starting issue, I remembered that the ecu I got had been opened before. I ended up opening it to see if it was blown. Turned out that it never had a chip inside. The PO obviously sold the chip :/
I would make sure that there is a chip inside. Of course, this would only be possible if you know that it has been opened.

If your check engine light and cluster lights all come on just before you spin the engine over, then you also know that the ecu chip is good. When I was having a problem, my check engine light never came on because there wasn't a chip inside.

Also, make sure that the fuel lines are not swapped.

Your wiring of the connector is all good.

Hope this info helps!

[SkorcherX]

You need to go through your wiring again. It seems that every single "guide" that just hands you the answers is wrong. You need to check what your car has, and what your M50 harness has, and make them match up.

If your wiring is truly good, then you need to test for air, fuel and spark. I am making the assumption that the motor already makes good compression.

No spark usually means either a bad coil pack (rare if all are bad, and it will run on 5 cylinders). If there is no ignition at all then I assume the DME is not getting any timing data. Check Cam and Crank position sensors again (including wiring/grounding).

No fuel? Check fuel pump relay. Check power to fuel pump. Can you hear the pump run for a second when you bump the key to on?

I did my swap with a NV M50 from an Auto. Nothing special is needed.

Good luck!

[David1665]

I went through the ETMS and consulted with someone who makes the adapters and those connections are now 100% correct. Still no fuel or spark.

I noticed my AFM is getting really hot?

also what is this plug?



Thanks again.

[R1dd1ck913]

I just did this swap with a 95 single vanos motor. That plug you are holding is for the auto tranny. I traced the wires back from that plug and cut them off since they are not needed.