Need Help Diagnosing A Cel Issue

[Timage]

Hey guys.

I've had my '98 Series 2 for nearly 2 months now and I'm still trying to sort out a problem. I originally purchased the car with the 2nd cylinder misfiring due to a faulty coil pack. During the time the check engine light would be on constantly (from the second the car started). The coil has been fixed for 2 weeks now and all was fine for about 4 days until the CEL came on again when I started up the car, only this time it took a few seconds to come on. I turned the car off and on again and all was fine for another couple of days. The engine would run a bit rough, but nothing compared to when it was misfiring and it would feel fine after I restart the car.

So over the past two weeks the light would randomly come on when I started the car, but would go out after I simply turned the car off and back on. Yesterday though I took it down to my mechanic pals and had them look in the ECU to see what codes were being set off. Apparently it was something to do with an 'ignition problem' or similar. They put it down to me using a newly cut key, and not the original key as it might have some transponder business built in that communicates with the car. They reset the ECU codes and I left.

Since then, the CEL is still coming on, but now after a few minutes of driving. The car however feels fine to drive engine wise. There is some shuddering due to the tyres needing replacing and balancing. Could the shuddering from the wheels be triggering the CEL? Or am I looking at an oxygen sensor (or some other sensor) problem?

Thanks in advance.

Edit: Should probably add that the car is completely stock aside from an aftermarket headunit and alarm system.

Edited June 5, 2009 by Timage

[QWK32]

C34 stagea's don't have a transponder in the key. i'm running a cut key in my car without a problem. and it wouldn't be the O2 sensor, if it was the error code would say its the O2 sensor (i've had this error code before). we could help you out better if you could tells us the actual error code number, e.g. 21

did you replace all of the coils in one go, or just the one? if you just did the one perhaps another one is on its way out.

another thing that pops into mind and would probably not be thought of is the PTU for the coils inside the ecu. this fault was discovered by user 666DAN, its for the R34 but S2 stagea's are the same ecu. if it is this fault and your no good at CB soldering and don't know anyone that is, it could mean a new ecu

Link to Fault

Edited June 5, 2009 by QWK32

[Timage]

Thanks for the reply mate. Hopefully I don't have that problem, but my problems seem very similar (although not as bad) aside from the stalling. I'll take the car back down to the shop this week and grab the exact code for you.

[Timage]

The ECU code was '21: Ignition fault'. Any ideas what's causing this? Would another failing coil pack be to blame?

[Timage]

Well I just did some research like I should have done before the above post and it seems the problem is mostly related to the coils, spark plugs or the wiring. I'll give them all a thorough check. Any other things I should check for?

[QWK32]

Well I just did some research like I should have done before the above post and it seems the problem is mostly related to the coils, spark plugs or the wiring. I'll give them all a thorough check. Any other things I should check for?

you've pretty much got it there. an ignition fault can either be, Coils (most likely), the wiring to the coils, the PT's in the ecu, or the CAS.

best thing would be to pick your self up a set of Splitfire Coilpacks, put them in, reset the error code and see how it goes. coils are the problem 90% of the time in ignition faults, especially if they are still the factory originals.