M42 Full Rebuild now won't start

[theTBLACK]

Spark verified...did you remove a plug, leave it connected and see the spark? I'd think that you'd get something, at least a misfire, if you spray ether into the intake while cranking if you had spark.

Could you have reversed the fuel feed lines? I think that if you connect them to the rail backwards you won't get any flow since the regulator doesn't really allow backwards flow.

Did you remove or disconnect the ECU at any point? Maybe it is not plugged in, or you forgot to install a chip? If you replaced the DME, it is entirely possible that there is no chip in it unless you opened it and checked.

1. Spark is verified

2. Fuel feed lines are correct.

3. I did replace the ECU. It is plugged in. I haven't looked inside of it though.

This morning when I went to turn it on, while it was cranking, the tach jumps all over the place. It is so strange.

[bmwman91]

Yeah crack the Motronic and see if there's a chip, and that it's fully seated.

[Boris3]

Might not need to crack the ECU since you had already tried swapping it with no change according to an earlier post, no?

Check the wiring to the blue temp sensor especially the condition of the wire before the plug end. This caused a no start situation (crank, spark and fuel but no start) for a friend of mine's e30 M3. Different engine I know but.... Someone had done a bad DIY fix that gave out.

[Dj Buttchug]

OP are you sure the timing is set on the TDC mark on the Crank (not the notch) This is a mistake that some make.

[theTBLACK]

Double checked timing and it's correct.

Went through everything again, rechecked the timing. Checked continuity to the dme, all the wire harness everything. Still have spark, fuel, etc and still no dice.

Here is a video of it cranking - check out the tach

https://youtu.be/AJ9aMW78W-0

[Dj Buttchug]

wtf. CPS no signal? im almost out of ideas...

[theTBLACK]

wtf. CPS no signal? im almost out of ideas...

CPS replaced and good signal. I'm stumped.

[uturn]

Is the engine ground wire attached?

[nk1221]

Doesn't the cluster get the RPM readings from the crank position sensor? Maybe it's a faulty sensor, have you tried swapping it out with a different one?

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[theTBLACK]

Is the engine ground wire attached?

Yes it is, but I'll double check!

[theTBLACK]

Doesn't the cluster get the RPM readings from the crank position sensor? Maybe it's a faulty sensor, have you tried swapping it out with a different one?

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I swapped it for a new one - perhaps the new one was faulty?

[nk1221]

That's what I was thinking! At least trying a different one will take that off the list of possible things.

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[mr.vang]

Unplugged the afm harness and crank it. See if that makes any difference in cranking.

[theTBLACK]

That's what I was thinking! At least trying a different one will take that off the list of possible things.

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I'll try the original and go from there.

[theTBLACK]

Unplugged the afm harness and crank it. See if that makes any difference in cranking.

Okay will do!