E30 coil problem?!! Help

[e30_harj]

I have a e30 2.5, and for some reason the coil keeps getting burnout, the car will initially start but then when turned off will not start again until its cold... any idea's??

[ranxerox]

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[e30_harj]

Well so far i have tried 3 coils on there, havent yet tried the same coil.. but im guessing either way, its when it cools down..

[ranxerox]

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[Rtaylor2208]

are you sure its the coil that's the problem? There are many other ignition components that can cause hot starting issues.

[Brianmoooore]

Far more likely to be the crank position sensor that's cooling down!

[Andy325i]

Far more likely to be the crank position sensor that's cooling down!

Can you expand on this Brian? Mine is sometimes hard to start when warm/ hot.

Sorry for the hijack!

[Brianmoooore]

When a crank position sensor first starts to go wrong (and it isn't the water pump pulley chewing through its cable), it tends to work OK when cold, and fail when hot, gradually needing to get less and less hot before it fails.
Unless your car starts to cut out when hot, with the tacho. dropping sharply when it happens, I doubt if this is what's stopping your car restarting when hot, although it's true that the sensor will initially get hotter after the engine stops, before cooling, as a result of heat soak from the engine.

[ranxerox]

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[Grrrmachine]

Would the crank position sensor failing cause the coil to fail, or is the assumption that the original and subsequent coils are o.k.?

If you try three different parts and the problem persists, would you believe the problem was caused by all three parts failing?

[ranxerox]

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[Grrrmachine]

The CPS won't destroy the coil, it'll just prevent it from providing a spark. No CPS signal = no fuel or spark.

In contrast, the simplest way to prove the coil is dead is to fit it to another known-working vehicle.

[ranxerox]

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[Grrrmachine]

Well, it's one of the things. Best work through this:

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

[ranxerox]

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[Grrrmachine]

It is my work, but it's just me typing up what Brian and the other experts have already said, so I can't take the credit for the info... just the presentation

[ranxerox]

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[Brianmoooore]

The best way to check the CPS is to identify its pins at the engine ECU plug (confirm by measuring about 540 ohms between the pins and mark the pins with a permanent marker), reconnect the ECU, then run the engine until it cuts out or to when you think it won't restart, then quickly unplug the ECU again and remeasure the resistance. If it's much higher or open circuit, then the CPS is duff.
Have you actually checked that the coil is not producing a spark when the car won't start?
It's also worth connecting a 12 volt bulb (a spare indicator side repeater complete with wire, but plug cut off, is ideal) between the coil + stud and body earth (main earth connection on top of the suspension turret) while trying to start the car, and confirm that is stays lit.