CID LEAD WHERE DOES IT PLUG IN please e30 1,6 1989

Post Thu Aug 10, 2017 7:18 pm

HI good folk. wondered if you could throw any light on this one . today while having a good look in the engine bay and cleaning the inside of the dist cap and rotor. believe its called CID lead coming of the n0 4 spark plug lead is not plugged in anywhere ?

also would like to read the faults codes from motronic 1.3 any one know how ?

thanks in advance. Paul

Post Fri Aug 11, 2017 4:04 pm

i NOW KNOW. WHERE IT PLUGSIN . FOR YOUR INFO if your fitting new plug leads. its attached to no 4 or 6
lead. over the top of engine thru water hoses down to a mounting plate. its the inside hole in the holder plate. below the scan tool plug. in the main wiring harness. next to the crank angle sensor plug in position ( not at flywheel end )
maybe help someone.

Post Fri Aug 11, 2017 6:16 pm

Sensor in question is a primitive equivalent on the M20/40 engine to the cam position sensor on later engines. Without its signal, the ECU will not know which of a pair of cylinders is close to TDC before the power stroke or before the exhaust stroke, and will fire both fuel injectors. If the signal is present, then, under certain condition, the injectors will be fired semi sequentially, reducing fuel consumption and emissions slightly.

Post Fri Aug 11, 2017 10:26 pm

o.k thanks for the reply wondered what it did. so i guess your be wasting fuel by injecting on exhaust stoke.
what does semi sequentially mean ?

Post Mon Aug 21, 2017 6:40 pm

I still can,t see where it plugs in. anyone please

Post Tue Dec 17, 2019 4:00 pm

I have the same problem as ArrisBMW, and cannot find the plug for CID. driving a 325i 86', and the CID plug is not connected, never has been in my ownership.
Have seen some models where it plugs in right under the diagnostic plug in the engine bay (intake side), but it surely does not on mine...

Post Tue Dec 17, 2019 7:20 pm

Didn't think this was fitted to pre '87 engines. Perhaps your ignition leads have been changed for the later version.

Post Wed Dec 18, 2019 8:09 pm

Brianmoooore
Thanks for you answer. I looked a bit more into it, and realized its different on an 325e (ETA) engine which I have in my E30. Apparently this engine has 2 sensors on the flywheel, and one on the crankpulley (only for diagnostics apparently).
Im not sure how it figures which cylinder its firing on from this, but think things is how they should be.
And like you said, the ignition leads has probably been reused from the old 325i engine

Post Wed Dec 18, 2019 9:06 pm

It doesn't know, or need to know, which cylinder is about to fire, to inject the fuel. There are only two wires from the ECU to the injectors on an E30, so the system is only semi sequential at best (three injectors fire together, followed by the other three) , and this only happens on post '86 cars under light load conditions. When you floor the throttle, all six injectors fire together.
The atomised petrol begins to turn back to liquid immediately, but is drawn into the cylinders before this happens to any great degree.
It's a crude system, but gives results that carburettor designers could only dream about.