M42 Full Rebuild now won't start

[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?

[theTBLACK]

Is the engine ground wire attached?

Yes it is, but I'll double check!

[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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[uturn]

Is the engine ground wire attached?

[theTBLACK]

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

CPS replaced and good signal. I'm stumped.

[Dj Buttchug]

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

[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]

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.

[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.

[bmwman91]

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

[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]

Spark has been verified. We have tried starting using ether, but to no avail. Perhaps I should recheck the injectors and everything else.

No stumbles. No partial-fires. Just straight cranking.

And that could be the case. I'll have to double check, but last I checked the timing was 100%. Ahhhh.

So many potential things. Thanks for the feedback!

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.

[nk1221]

Yeah I would try swapping injectors with some known working ones and go from there!

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[theTBLACK]

Did you somehow mix up the cam and crank position sensors? It's unlikely since the plugs should more or less face the right way, but you never know.

How did you confirm that you are in fact getting fuel into the cylinders? Raw gas smell in the exhaust? How about verifying spark?

Could you have mixed up the ignition coil plugs? At start-up things are in wasted spark mode with plugs 1 & 3 and 2 & 4 paired. If you mixed up the coil connections just right, you'd get no combustion. Do you get any stumbles or partial-fires, or nothing at all?

Is there any possibility that you got the crank 360 degrees off from the cams (cylinder 1 at TDC of the intake stroke rather than the power stroke)? You want things physically aligned as shown in the left-most part of the bottom diagram of the first post:
http://www.r3vlimited.com/board/showthread.php?t=374858

Spark has been verified. We have tried starting using ether, but to no avail. Perhaps I should recheck the injectors and everything else.

No stumbles. No partial-fires. Just straight cranking.

And that could be the case. I'll have to double check, but last I checked the timing was 100%. Ahhhh.

So many potential things. Thanks for the feedback!

[theTBLACK]

OP, did you get this figured out?

Unfortunately not.