Stalls on tickover

[theretroking]

My 318 coupe over the last couple of days has decided to stall on tick over, it runs smooth on tick over and some times decides to die, it seems like an electrical issue but haven't an idea to what it could be. also when driving on a couple of occasions it looses power for a second, the rev counter shoots down then comes back to the normal RPM, anyone help.

[theretroking]

anyone help

[Grrrmachine]

1) What year is this car? And it's not a coupe, it's a 2-door saloon.
2) Does it do this when hot, or cold, or both?

If this is a post-87 car, I'd be tempted to think it's the Crank Position Sensor. It's one of the few parts on these cars that's worth swapping over just for the sake of having a spare, so that it doesn't leave you stranded somewhere.

[theretroking]

hi its a 1991 coupe 1.8, fault occurs whether its hot or cold, sometimes if left ticking over every so often the tick over will die but not enough to stall only when left standing, hope this helps you to help me.

[Brianmoooore]

1991 1.8 2 door saloon = M40B18 engine.
The rev. counter drop outs indicate an occasional electrical fault, as you suspect. Try a second hand replacement DME relay (white one under the bulkhead wiring cover) and see if trhat improves things.

[theretroking]

Cheers Brian any pics to which one, cheers a˜€

[Brianmoooore]

Under the wiring cover on the bulkhead, between the fusebox and the centre of the car.
There will be three relay sockets under there - the relay you want is the five pin one, which is probably white. There will also be a four pin relay, probably orange, and either an empty socket, or another four pin relay.

[theretroking]

Thanks for all your help, I'll get the relay and let you know how I get on.a˜€

[theretroking]

Would a 1.6 relay be the same as the 1.8 ?.

[Brianmoooore]

Most things on a 316 are the same as a 318, and the DME relay is no exception. Same part on all other E30s as well, except for really early stuff, and also on many other later E30 models.

[theretroking]

Hi back again after sometime, the issue stopped on its own, unfortunately it re occurred today so I replaced the white relay which was advised but has not cured the problem any other ideas anybody, much appreciated.

[Brianmoooore]

Pity! That was the cheap and easy option.
The other two likely suspects are the crank position sensor and the engine ECU. Crank sensor failure is fairly common, but is usually heat related in its early stages. Much more rarely the ECU is found to be at fault, but the one case I've come across was on the same engine and about the same age as yours. Take your pick as to which to go for next.
I suppose a third suspect could be an aftermarket immobiliser or the OBC 'code' immobiliser. Do you have a 13 button OBC in place of the analogue clock or an immobiliser?