Intermittent engine cutting out - arrgh!

Mon Mar 31, 2014 11:45 am

Hi All,

I have an annoying engine cutting out issue on my 325i touring. It cuts out completely at random (i.e. no difference if accelerating or at tick over). It will cut out for a second or two (quite violent if I am accelerating at the time) and then come back again. Sometimes it will go for several journeys without doing it, but it always comes back. I am a bit at my wits end now, so wondered if anyone had any other advice for me.

To describe it in more detail - tts definitely electrical - and similar to others who have posted on here, but none of the approaches I have tried to date have worked

I will cover off the things I have already tried and replaced
- HT leads, dizzy cap, rotors arm etc
- Fuel pump and filter
- TDC sensor replaced
- Fuel pump relay

Things I havent really touched
- Air Flow Meter - although I havent done this as it looks like it has been worked on or replaced pretty recently.
- Gounding - I have ordered a new ground strap off the battery, and one off the alternator to see if they do anything.

Any thoughts on anything else I can try I would really appreciate it! It does feel like some sort of loose electrical connection...
Thanks v much in advance,
David

Mon Mar 31, 2014 12:18 pm

Have you checked the engine-to-body earth strap? This usually goes between the engine block/mounting and the front chassis leg.

Also could be worth trying another ignition coil - perhaps yours is on its way out...

Mon Mar 31, 2014 1:04 pm

What does the rev. counter do when it cuts? Drop like a stone, or decay as the engine slows?

Mon Mar 31, 2014 1:14 pm

Thanks for the ideas - I'll check the engine to body earth strap. Should have mentioned I tried new ignition coil.

The revs drop like a stone when it cuts - it's quite disconcerting. Although I'm used to the fact it will come back again now. I really want to get it sorted now as I'm taking it on a long trip and I want it gone before then (otherwise my wife will start making noises about getting rid of it again! ;))

Mon Mar 31, 2014 1:20 pm

If it drops like a stone, that narrows things considerably - won't be anything to do with ignition coils, distributors, fuel pumps, etc.
First thing to try is the DME relay (white relay, under the cover by the AFM). No need to try a replacement - just pull the existing one out and use two pieces of wire to link together pins 30 and both 87s of the relays socket. Drive it like this and see if the problem is sorted.
Remove the links when you stop, since this is the equivalent of leaving the ignition on.
Relay pin numbers are on the side and bottom of the relay.

Mon Mar 31, 2014 3:39 pm

As Brian says, it's either the DME relay or CPS.

Mon Mar 31, 2014 8:14 pm

Hi - thanks, I checked the dme relay and no difference (thanks for the tip!) - what's a CPS?
Cheers
David

Mon Mar 31, 2014 8:17 pm

I did remove the engine block to chassis earth and cleaned it and so far the car hasn't stuttered since - so I'm really hoping it might have been this! I'll keep tabs on it for now...

Mon Mar 31, 2014 8:19 pm

CPS crank position sensor

Mon Mar 31, 2014 9:10 pm

http://www.e30zone.net/e30zonewiki/inde ... ion_Sensor