M42 Swap- HELP!

[McMadCow]

Our crew is finishing up an M42 swap into my 74 2002 using JakeB's instructions. The swap itself is done, but there must be something wired incorrectly because the engine won't fire up and we're not getting spark.

Has anyone else in the Bay Area done this job and can offer some advice? Better yet, does anyone want to visit the garage in Petaluma and help us out? Beer and food is on me!

PM or mcmadcow at gmail dot com

Thanks!

[M5wanaB]

I'm up in sacramento and have a good running M42 in my 76. I'm not real sure about your spark problems but are you using the stock coils? You should check for voltage at the coils and make sure you have everything grounded well. Other than that make sure you have your power wires for the ECU hooked up right there should be 2 one with constant voltage and one with switched voltage. I believe the M42 gets spark signal from the cam position sensor so check that out too. I went straight to coil on plug instead of dealing with the plug wires. The e36 bently manual has good testing proceedures for all the sensors and voltages. Id start there. Good luck and if I'm in the area ill hit u up.

[McMadCow]

I'm up in sacramento and have a good running M42 in my 76. I'm not real sure about your spark problems but are you using the stock coils? You should check for voltage at the coils and make sure you have everything grounded well. Other than that make sure you have your power wires for the ECU hooked up right there should be 2 one with constant voltage and one with switched voltage. I believe the M42 gets spark signal from the cam position sensor so check that out too. I went straight to coil on plug instead of dealing with the plug wires. The e36 bently manual has good testing proceedures for all the sensors and voltages. Id start there. Good luck and if I'm in the area ill hit u up.

Thanks for the reply! We have tested voltage to the coils, and they go get voltage when the key is turned to ACC. What we're not getting is the trigger when we crank the engine.

Something you hit on that I know we're missing, though, is when you mentioned constant voltage and switched voltage to the engine wiring harness. We have our switched voltage going through a pin on the C101 connector, but we don't have any constant voltage hooked up. I was wondering about that, but didn't see anything in Jake's writeup. Do you have any info- or better yet, a wiring diagram or pictures- on where the wiring harness connects to constant voltage? Any info you have on how the starter is hooked up would also be great.

Cam and crank position sensors are both new in box for this project.

I'll keep updating as we narrow down the issue. We have a CEL, so we know we're only a couple of plugs away from a running motor...