1994 E34 - 530i Not Starting - Looking for insight

[jroush]

Helping my son with a 530i which will not start after replacing the bad engine with a used one, but without guaranteed history on the replacement.

Car cranks fine, compression OK on all cylinders, new plugs which fire, fuel pump running. Went through the various inputs to the DME and all inputs seem reasonable, although without firm specs on each, having to "deduce" on some.

Lab scope shows what may be the problem. Crank sensor, cam sensor and ignition waveforms are "right on" . However the injection pulse seems to be 180 degrees out of synch. The scope shows the injector pulsing immediately before the spark plug fires, but that would be with the valves closed on the compression stroke. The injector should be pulsing at the end of the exhaust stroke so the fuel is pulled into the cylinder on the intake stroke.

Doing a lot of searching and reading trying to find what causes the DME to set the injection pulse timing in case something "feeding" the DME is causing the problem, but have not found anything yet. Have the feeling that it will be something simple that I/we missed, but needing the insight and wisdom of those with more experience in the area than myself.

Suggestions? Reference links that provide detail information?




Thanks

[westin]

Thats a hell of scope you got there those are pattern though back probing? the cam to crank wave paternare a bit off ussually cam to crank its 2 to 1 but i need to double check that.

[westin]

On more thing for.analog wave the crank sensor looks really choppy,unless the scope setting its a bit of for the frequency,the cam sensor looks weird too,no codes?

[jroush]

Thanks for the inputs.

Pattern looks better at smaller/shorter time interval, but wanted to show something approaching a complete compression cycle.

Will have to recheck codes, but last check which was a few weeks back, not getting any. Had hoped to get something which might indicate a problem in the CAN modules communications which was causing the problem, but not that fortunate.

[jaysettle]

jroush did you ever figure this out? I'm having the same problem. My e34 1994 m60 will turn over strong but wont catch and start. I just bought the car a week ago and was driving it everywhere no problems. Then this morning it would not start. Tonight I've covered that my engine is getting clean spark. I've checked the fuel pressure right before the fuel rail and it builds up strong when I try to start the car. I've hooked an oscilloscope up to the crank position sensor and get a sin wave similar to yours in your pic. I've checked compression as well at about 90psi in the front right(passenger) cylinder and 85psi in the cylinder behind that. Not sure what else this picky engine needs to ignite fuel?? Any progress on your situation?