died on track - no spark!

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325ie30
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Tue Oct 28, 2008 1:57 pm

Hi all, I'm afraid it's the old 'no sparker' again! Hope someone can help...

It's my '87 325i (pre-facelift) weekend / track car.

It just died while on track, when tested at home there's no spark but still pumping fuel..

Have 12v at the coil, tried another in case but no difference. Tried Brianmoooore's lightbulb trick between coil + and body earth, with plug attached straight to lead from coil. When cranked, light stays brightly lit (freshly charged battery) but there's no spark.

ECU is a xxxxxxxxx 073. Someone on here mentioned that these are prone to failure, might my situation be a symptom of that? No signs of scorching inside, don't know how to test further.

Crank position sensor - bit confused here. Seems to be a favourite suggestion on here to replace this. Tested for resistance, got about 2.5 K ohms but not a very trust-worthy reading on the cheap meter!

Thing I don't get is that the 3 wires from it go only to 3 pins in the diagnostics plug and don't seem to be connected to anything else, So... how does it do anything?? It's not the allen key bolt type, it just clips in on the front of the engine.

Haven't thrown any other parts at it yet as I can't afford to start doing that until I think I know what the problem is!!

Any suggestions on where to go from here would be great!

Cheers
Richard
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Ant
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Tue Oct 28, 2008 2:03 pm

These are prone for dropping the TDC keyway from the flywheel on trackdays( especially if chipped to over 6.6K limit )

pull the lower gearbox extension off under the sump and have a peek inside using a mirror and torch, you may need to rotate the engine to see whether the TDC key has gone adrift........ if its not there then a new flywheel will sort it, but only the correct prefacelift unit will do !!
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325ie30
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Tue Oct 28, 2008 2:28 pm

Damn that sounds awkward! :?

Thanks for the info Ant, sounds plausible especially as I took a slight 'scenic route' across some bumpy grass at one point!

Will go and get stuck in... : )
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Brianmoooore
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Tue Oct 28, 2008 8:52 pm

Far better idea than pulling the flywheel out, is to upgrade the whole management system to the later type.
325ie30
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Tue Oct 28, 2008 11:42 pm

Rain stopped play (along with lack of torx sockets) so not checked if the flywheel is ok yet..

What would upgrading the entire management system involve Brian? Obviously later ECU, but what else? And would it be easier or cheaper than changing the flywheel? (if that turns out to be the problem...)
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Brianmoooore
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Wed Oct 29, 2008 8:50 am

Management change is far easier than flywheel changing, unless you're taking the gearbox out for some other reason.
You need a complete engine loom from a later 320 or 325, the toothed wheel and crank sensor off the front, and the oil pressure switch (different plug). Also needed, is the ECU, of course, and this can be a 325 one or a 320 version fitted with a 325 'chip'.
325ie30
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Wed Oct 29, 2008 1:53 pm

Ok, found a donor in a scrappie, heading there shortly.

Can anyone please tell me what the oil pressure switch looks like and where it is??

Should I be able to get all that stuff (particularly toothed wheel) off a car with:
socket set
screw drivers
allen keys
spanners
knife
hammer winkeye
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