CID sensor..

[Boomy]

Realised that the sensor and cable on my 318 cab has broken off the HT lead.I had no idea what the cable was for, but searched the wiki to see it should control injector firing.

Should it idle and run perfectly well with it off? Just did a 100 odd mile trip and it was flawless! In fact things seem better than when it was attached

[TPS]

I don't think that controls injector firing, the C101 does that.

[jmc330i]

The C101 plug is the where the engine loom joins to the car, on the bulkhead near the fusebox.

I think without the cid sensor connected, the injectors all fire together. The car will run fine without it, but I believe will be better and possibly more economical with it connected.

[Brianmoooore]

It's signal is used by the ECU so that it can fire the injectors in groups of two under certain conditions. Without its signal, the ECU has no idea which of a pair of cylinders is on its compression stroke, so has no option but to fire all four injectors at the same time.
Your engine will run fine without the signal, but it will run that little bit better with it, especially under part throttle conditions (i.e. most of the time), assuming everything else is as it should be.

[Boomy]

http://84.45.115.78/e30zonewiki/index.php/CID

Righto.

Is that thing in the link above.I changed the HT leads and managed to snap it off! I assume you have to buy a genuine set of leads to replace it as there seemed no way other than cutting the leads to get it off and back on?

[Brianmoooore]

Plenty of second hand leads available, most in as good a condition as they were twenty years ago.

[Boomy]

Just to confirm, this has nothing to do with the C101 bit mentioned? If not, where does the end of the CID lead go to? It looked to me like it ran down through the timing belt cover somewhere (was dark mind you)

[TPS]

I think it goes to the Black Diagnostic socket.

[Brianmoooore]

Just to confirm, this has nothing to do with the C101 bit mentioned? If not, where does the end of the CID lead go to? It looked to me like it ran down through the timing belt cover somewhere (was dark mind you).

Nothing remotely to do with the C101!
Connects to one of the sockets on the wiring box under the inlet manifold.

[TPS]

My Mistake

[Brianmoooore]

I think it goes to the Black Diagnostic socket.

Early M20s had a crank position sensor that only supplied a signal to the diagnostic socket.

[TPS]

I have to go in the garage & look at the M40, My 325 has the 2 connectors one for the CPS & the another the HT lead sensor, below the diagnostic socket, I always thought the M40 was similar.

[Brianmoooore]

On all but early M20 engines the two plugs fit into sockets under the diagnostic socket, but the wires don't go to it; they go to the ECU. Same on the M40, but the sockets are mounted further back.