I just swapped in an m50 1995 325is Motor with an s52 1998 m3 and currently using the obd1 harness with the s52. On the s52 I have crank sensor, cam sensor, intake manifold/throttle body, fuel rail,harness and fuel filter from the m50.

I have the 325is e36 body and with the original motor I was driving and it just started to die as if the fuel pump just died. Stopped on the side of the road and tried to start it and there was back fire in the intake manifold! So idk if that could be cps Bc it’s on the s52 right now. I did find the fuel pressure regulator was disconnected so that could be the back fire but the s52 does have the same cps.

I did splice the wires for the water temp sender from a two plug to one plug and that’s all the splicing I did.

After putting the motor in the car cranks and doesn’t start. There is Volts to the coil packs but no fuel. I did jump the relay and the fuel pump works so I’m thinking the dme.

So I have three dmes one with the s52 two for the m50 red label 413 they all crank and no start. I know it didn’t run yet but with the s52 no cel but I also would think it’s not running Bc ews but I think it’s not suppose to even crank? But for the two m50 they both have cel that’s it and they crank no start as well.

What I read up was a lot of people saying it could be the crank position or the camshafts position sensor.