M50 swap no start

[shiboujin]

The harness and ECU is from another e30 M50 swap. The motor is of unknown quality as it's a junkyard special. All the connectors are hooked up minus the O2 sensor. All of them are similar plugs and pin numbers so i'm not sure if everything will hook up.

The car will crank. Each injector fires. I did the old ear to a screw driver trick. I can smell the fuel out the exhaust. I spark tested so I know I have spark. I thought maybe the coils were the wrong type so I swapped the stuff over from the other m50 swap I had.

So I have fuel and spark. Not even a stutter. The tach sits at about 500 while cranking and jumps to 1k for a brief second every revolution.

Thoughts?

[pr0craztinazn]

You should edit the title to say "M50 swap has spark and fuel, won't start". To be specific, the engine is a non-vanos M50 and has a brand new cam position sensor and a used crank position sensor. The harness used is from a running '88 325is with a non-vanos M50, and the car the harness is in now is an '87 325e. The cluster in question is a Motormeter unit from an '87 325i.

[pr0craztinazn]

The fuel supply and return lines were reversed on the fuel rail. Swapped them and it fired right up!

[ForcedFirebird]

Common mistake actually, glad you got it sorted out!

[pr0craztinazn]

The car had a terrible idle once it warmed up; swapping ECUs only temporarily fixed the problem. Swapped the blue relay (O2 sensor?) with a spare and after some initial re-learning time, the car idles pretty well and power delivery is greatly improved. Need to figure out where to mount the relays so they won't soak up water when it rains...