help! injectors not fireing

[jaysee]

replaced the engine speed sensor and the car started right up. i used a sensor from a 735i m30 i found in a salvage yard, it was a tad bit longer like 2mm so i put a spacer in so it would match the length of the eta sensor.

[jaysee]

So got my new (used) dme in the mail today installed and same problem.. my referance sensor is in spec per bently but the engine speed sensor is out of spec by. Like 3 ohms. Gonna replace. That when I can find one.. andd probably rewire the injector harness tomarrow

[jaysee]

so ppl were telling me that there should be 12v from both sides of the injector plug with all the injectors disconnected,
but from what i understand on this wiring diagram it shows there shouldnt be 12v from the wire going from the ecu to the injector with them all unplugged
is this right?

[jlevie]

The ICV should vibrate when the ignition is on if the idle switch in the TPS is closed.

[jaysee]

also i noticed something yesterday the iac runs constantly if the key is in the on position is that normal?

[jlevie]

It sounds like the harness is okay and the DME is bad.

[jaysee]

that is most likely to be the dme correct? if i can click the injectors on on each bank by grounding the connector pin for the injectors to the dme,that would mean most likely the harness is intact? sorry.. just wanna make sure

[jaysee]

just scoping for a cheap eta dme if u know someone thats got one dirt cheap let me know

[jaysee]

yeah i just confermed my problem is the dme, if i ground the pin for the injectors at the dme connecter the injectors click on. and all powers and grounds are good on the dme harness. also all my sensors checked within spec. gotta love the bently manual

[jlevie]

To check the wiring harness you ohm out the two injector control leads from the DME connector to the injector connectors (with all injectors disconnected). You have power to the injectors and spark, so the only things left that can cause the injectors not to fire are the engine harness or DME.

[jaysee]

i never dissconnected them, but there could still be a problem, ill check the resistance reading on them tomarrow, i do have spark though.. what one would have to be bad for me to have spark but no injectors? and thx for the luck i need it

[RagtopE30]

when you did the head gasket repair did you disconnect the sending units that are attached to the bellhousing? If you did make sure they are connected correctly, they both fit in both the female sides of the wiring harness but the engine will not fire if they are not connected properly. Try switching the two plugs with one another and see if that works. another thing is to make sure that the two sending units on the thermostat housing that were hiding in the pictures are connected properly. The wire harness ends should have matching colors for the sending units they belong to. There are two brown connectors but only one is long enough to reach the furthest forward sending unit the other brown one goes to the sending unit closer to the fuel rail. Good luck

[jaysee]

okay.. i thought it would only show on both sides if the harness was still pluged into the injector.
how would i go about checking for a wiring fault?

[jlevie]

so it is confirmed the injectors are not firing, checked with a noid light, cheacked for voltage @ the injector and there is an even 12v wierd thing is, there is 12v comming out of both sides of the plug, one should be positive and the other negitive but they are both possitive? wtf? anyone have any clue what would cause this? or is there anyone in the west michigan area that has a extra eta ecu they would let me plug in to see if mines bad?

System voltage is supplied to the injectors and the DME grounds one side to cause them to fire. So seeing 12v on both pins is normal when the DME isn't firing the injectors.

It sounds like the injectors have power, but no firing pulses. If the engine has spark when cranking the cause will be a wiring fault or a bad DME.

[jaysee]

i checked voltage at the harness plug with it detached red to plug, ground on engine