'89 E30 325i Sport - Cutting out whislt driving and stopped.

[Bigbenstrikes]

Hi guys,

My car just developed a problem today whilst driving along the revs dropped and then came back to life after 2 seconds, also when stopped it just cut out. Starts again fine.

It seems to happen as the engine is hot and the rev counter dips when it stutters whilst driving. Is this an ignition problem? Read on here it could be the DME relay?

Thanks again.

Ben

[jimbom30cab]

Are your battery and earth connections tight?

Do the revs drop to zero like the engine has been switched off?

[Bigbenstrikes]

Yeah connections are sound.

It doesn't go right down as it starts back up again before the needle has chance to fall completely down..

[Bigbenstrikes]

I don't need to restart the car whilst driving it just seems to go dead for two seconds then jump back into life.

[jimbom30cab]

Have you tried swapping the dme relay for a known good?

[Bigbenstrikes]

It's only started tonight and I got a long drive ahead of me tomorrow.. state of urgency here! Haha I can probably get one tomorrow afternoon. I read about bridging contacts on the relay. If I do that will it get me to Inverness from Glasgow? Also what size cable would I need?

[Brianmoooore]

A bridged DME relay will get you to anywhere you want, if that is the fault. Just don't forget to remove the bridge when you park up, as leaving the links in place is similar to leaving the ignition switch on.
Any wire will do that will make decent contact with the buckets in the relay socket, but not so big as will damage the buckets. Link 30 to both 87s
Plenty of other things that the problem could be, but if it's not engine temperature dependant, then the DME relay is high on the list of probabilities.
If the problem persists with the DME linked out, then connect a 12 volt bulb between the + terminal of the coil and the car body, position it somewhere that you can see it when driving, and check whether it stays lit when the car cuts.

[Bigbenstrikes]

Cheers Brian, I shall give that a bash tomorrow! It does seem to only happen when the engine is hot!

[Bigbenstrikes]

This DME relay is the one on its own on the inner wing near the power steering reseviour? Got a black plastic cover over it?

[Brianmoooore]

DME relay is the 5 pin one (usually white) where you say it is.
Heat related cutting out is often the first signs of a failing crank position sensor, but you usually have to let them cool for a while before the engine will restart.

[Bigbenstrikes]

I see, well it starts again fine, sounds like the relay is just packing in. I shall bridge it and see what happens! Thanks again!

[Bigbenstrikes]

Replaced with links this morning and all was fine. Only after about 1.5 hours driving and going through some stop start traffic the engine heats up and it started again. Not as bad this time but certainly something. The links were in solid but it still persists, its only intermittent and when it cuts back in it shoots forward as if there is a build up of fuel and air in the cylinders then it suddenly ignites. Checked the earth and its tight as and so are the connections at the dme relay. Definitely seems to be when the engine gets hot.

[Grrrmachine]

If it happens with heat, it may be that your CPS sensor is on its way out. When they're near the end of their life, they start failing at temperature. Might be a good idea to get another one on order, just in case.