E9 m30 3.0 si 1973 injection problem

[Maciek98]

Hello everyone

My name is Maciek and I am an apprentice in bmw in south of France.

I am working on e9 m30 3.0 si
My cylinder 2,4,6 injector don't have voltage on it via oscilloscope .
1,3,5 are good and are alimented .
I already check the continuity from injector to the computer who is new i changed the old one.
So the lines are good .

I don't understand why my alimentation to injectors is Okey but when I measure on oscilloscope 2,4,6 injectors they don't work.

We send injectors to bosh verification and I permuted recently to see if problem will migrate and after oscilloscope mesurment it s still the same 2,4,6 dont work.

We think it may bee some relay or something like that ...
If you have any suggestions I will be grateful.

 

[Arde]

Welcome Maciek.
I would check continuity (like you did) and also resistance to ground, and resistance between each line, to make sure the lines are not shorted to ground or to each other. I would measure this without the computer plugged in and without the injectors connected.

Besides that SFDon here is the expert and can surely diagnose it without seeing it...

 

[sfdon]

Maybe this helps..

autobooks_manual_160

autobooks_manual_160

www.e9coupe.com

 

[Maciek98]

My control of injectors resistance was without

Welcome Maciek.
I would check continuity (like you did) and also resistance to ground, and resistance between each line, to make sure the lines are not shorted to ground or to each other. I would measure this without the computer plugged in and without the injectors connected.

Besides that SFDon here is the expert and can surely diagnose it without seeing it...

Resistence is ok between each line the same and the injectors were disconnected its have to be disconnected to get the resistance :/

 

[Maciek98]

Maybe this helps..

autobooks_manual_160

autobooks_manual_160

www.e9coupe.com

Thank you but I already have it from manual from the forum

 

[Maciek98]

Here some photos the igniter and bolt plugs are new

 

[sfdon]

If you changed the computer and you tested the injectors- then its the wiring.

 

[sfdon]

Check for short at wires to connectors at injectors

 

[Maciek98]

The problem is that the wiring was tested by continuity and its good :/

 

[sfdon]

One of the positive wires is shorted to ground
It will still have continuity to the computer

 

[sfdon]

Start by pulling the rubber boot back from 2,4,6 injector connectors.

 

[sfdon]

Check for ground at 2,4,6

 

[sfdon]

options

injector no good- tested

computer no good - changed

ground missing for 2,4,6 - did you take off ground wires at intake?
is ground wire bad at intake?

short at harness- voltage goes to ground not to injector

 

[sfdon]

Check for injector that is shorted to ground.

 

[Maciek98]

All of this controls are okey

 

[Maciek98]

What about that it seams to be a injection relay

 

[Maciek98]

We will start by changing those 2 boys and change connexions to continue the diagnosis when we stick the 2nd relay "1st is with starter red cable " the engine run well so we think it was the problem of this car

 

[tferrer]

There is a great deal of corrosion on that relay. Clean up ALL the connections in the injector circuit. It may not be your issue but it surely can't help the situation. If all else fails, I'd get some eye of newt, an eagler feather, a vodoo manual and start learning how to cast spells....

 

[Maciek98]

We already start necromancy and sacrifice didn't helped yet
yeah tomorrow I will try to get them out the corrosion goes even inside the relay but the Cooper seams good we tried to clean them quickly but it doesn't help need to do it properly and take time now it's end of the work day

 

[sfdon]

Main relay with 2 white wires pin 87 to computer