M50NV misfire urgent help needed

[booomer]

Hi guys,

My E30 M50NV has developed a misfire having been parked up for a couple of months and i'm struggling to diagnose it. My strobe light and multi meter are telling me that the coil is not being fired and the injector not being cycled on cylinder 4. I have tried a new plug, and i have swapped coil packs and injectors around but still no power to anything on cylinder 4. I've even swapped the ECU to no avail. I guess it looks like the ECU has detected a problem so its powering down the coil and/or injector.

The next thing i'm going to try is to test the wiring but dont know which pins on the ECU plug to probe. Does anybody have an ECU pinout for this age of engine? i can't find one anywhere on the google!

[motormanmick]

Check out electrical manual on link below
1991 BMW 525 is the one to look at, has m50NV ecu layout

http://www.wedophones.com/BMWManualsLead.htm

[Brianmoooore]

Also here: http://www.autolib.diakom.ru/CAR/BMW/19 ... 0DIAGRAMS/

[booomer]

thanks guys,i'll try and let you know what happens

[booomer]

wiring from ECU to injector and coil both fine...

bought a code reader, and handily it doesn't work

[motormanmick]

Just a thought, if the wiring from ecu to injector and coil are fine, it could be an earth problem, check to see if the earths for the coil and injector are both going to the same point and that they have a good connection to earth, good luck.

[booomer]

turned out to be a hidden split in the idle control pipe that connects to the main inlet hose. Very strange that it was only causing cylinder number 4 to skip both injection and ignition. sorted the pipe, now running fine!

[motormanmick]

Good one, well spotted

[booomer]

For anyone experiencing the same thing, just be wary that for some reason bmw changed the idle control valve hoses slightly some time in 1992/3. They still fitted mycar but they may not be quite right for yours