Help: M50 Cranks But Won't Turn Over

[tomgt325]

what motor is this, m50nv or m50tu? have you ome'ed out the crank position sensor? (check to see if the sensor is good)

Yea I checked both the cam and crank position sensors, and they both read the correct resistance.



Question: Does running a wire from the dme to the strut tower ground provide a temporary proper ground?

[gregslow318i]

what motor is this, m50nv or m50tu? have you ome'ed out the crank position sensor? (check to see if the sensor is good)

[dirty30]

dme doesn't need to be grounded.

lol

[Chrisv006]

This reallllly sounds exactly like what I was going through...even the fuel pump getting power with the ignition off.

A new main relay cured everything.

By the way - what year e30, what m50 motor, what ecu and how about your x20 -> c101 pinout? Id post my huge long toubleshooting list of things to check but I want to make sure it applies to you and wont just lead you down the wrong path.

[tomgt325]

You need to get a better idea of what your lacking; spark or fuel. i would test the lines leading to the crank sensors, and the coils, via the dme hub. i think that will be the most telling information.

I'm lacking both fuel and spark. And I'm not positive what you're referring to when you say dme hub. Diagnostic port that's close to the dme?

I'm almost leaning towards having two bad ecus. Pretty crummy luck, and slim chance, but otherwise I'm at a bit of a loss.

[call me jack]

You need to get a better idea of what your lacking; spark or fuel. i would test the lines leading to the crank sensors, and the coils, via the dme hub. i think that will be the most telling information.

[tomgt325]

Have you tried to jumper the main relay then start? 30 to 87/87a.

That ended up being the broken part for me.

I jumped both the fuel pump, and the main relay and it still did not start.



Something weird happened as well, when I jump the fuel pump relay the fuel pump starts even if the key is in the ignition turned or not. Is this supposed to happen?

[Chrisv006]

Have you tried to jumper the main relay then start? 30 to 87/87a.

That ended up being the broken part for me.

[blackhawkimpact]

DME doesn't need to be grounded.

[tomgt325]

Is the case of the dme grounded?

Literally ran a wire from the case to the strut tower grounding point just in case. I also bolted it up too.

I would double check your fuel pump situation. My case was a bit special because I started with a shell, so the wiring was completely random. But I was having that problem and it was because the fuel pump wasn't getting power. Should put a multimeter to the power source at the fuel pump and turn the key to run. (sounds like you know this already, but I'm just checking).

You should actually be able to hear it prime the system if you just turn the key to run...

I've jumped the relay and the pump will get power, but it still won't turn over b/c of the lack of spark...

[freeski27]

I would double check your fuel pump situation. My case was a bit special because I started with a shell, so the wiring was completely random. But I was having that problem and it was because the fuel pump wasn't getting power. Should put a multimeter to the power source at the fuel pump and turn the key to run. (sounds like you know this already, but I'm just checking).

You should actually be able to hear it prime the system if you just turn the key to run...

[dirty30]

Is the case of the dme grounded?

[tomgt325]

Does the engine have the EWS immobiliser system?

No, I'm using a red 413 dme

[Cook]

Does the engine have the EWS immobiliser system?

[tomgt325]

Check if you get power to the coils or if the main relay is triggered on or if the fuel pump relay is triggered on as well,you can check if you get power on the green unfused wire if not then right next to the abs ecu there is a black box ,that black box has 4 wires ,two of them are green, try to jump those two wires and see if it's going to start or at least trigger the main and fuel pump relay and if it does then that relay has a burn circuit inside,I can't remember in this second the name of relay but it's related with the OBC( you can put a password code in the OBC and if you want to start the car and you don't put the code in the OBC ,the OBC will not trigger that relay and the car won't start.

I have a 6 button OBC if that matters. Trying this tonight.....