bmw no spark when hot

[e30daniel]

hi guys. im having a very interesting problem with my bmw 325se.

basically from cold the engine will start pretty much perfectly first turn of the key. as it gets hot it still runs perfect until it loses spark and dies.

does anyone have any simple ideas of what it could be.
tomorow im going to check the coil, temp sensors, tdc sensor and the dizzy and rotor arm again.
thanks

[Brianmoooore]

Very likely to be a failing crank position sensor.

[e30daniel]

i just changed it. it seams to work every time from cold. i checked today and same problem with a few crank sensors i have and they are working perfect on his. i checked the dizzy and rotor arm today and they looked extremely worn. think this could be my problem with not spark when warm?
thanks

[Brianmoooore]

Working when cold and failing as the car warms up is what crank sensors tend to do as they start to fail, until they finally give up.
Next up is to try a different DME relay, and then a different ECU. Although ECU failure is extremely rare, it turned out to be the culprit the last time I had this problem!
You could try connecting a bulb or LED between the coil + and earth, and positioning it somewhere that you can see it when driving.

[e30daniel]

so chances are its not the dizzy or rotor arm then even though they look well worn. its a bit weird to have two dodgy crank sensors out the bunch or is that just bad luck lol.

il order a new crank sensor then and a new dme relay and see how it goes.

[Brianmoooore]

Don't go splashing out on new bits! Second hand or borrowed will be fine, for testing purposes at least.
That's what the zone is for.

[e30daniel]

i think you might be right on the crank sensor. does anyone here have a spare sensor i could try to see if that is the problem.
much appreciated.
thanks

[Brianmoooore]

You might have more luck with that request if you give the rest of us some indication of where you are!

[e30daniel]

oh im in the glasgow area. sunny scotland. i would be willing to pay for postage if need be. if anyones got one to buy i would be interested too. thanks

[Mayze]

I had a similar problem myself which Brian diagnosed it turned out to be a corroded connecter on the plug under the inlet manifold.

[Brianmoooore]

Corroded C192 won't make it lose sparks. C192 will make it overfuel, or lose either three or all six cylinders.

[Mayze]

Ill get back in my box then.

Sorry Brain