yeah, car was running fine, and i suddenly notice my tach dropping for a second, then cmoing back up, accompanied by the car surging. i pull into a neighborhood street and find myself running on what seems to be about 2 cylinders...
i hook up the logger, check the codes, find a code for ignition coil.
ok, i figure i'll get home, put in a spare coil and be done in 10 minutes. well, 10 minutes later, i fire it up, still on 2 cylinders!!!! oh, my afc rpm and stock tach no longer match. afc is double what the tach says.

what controls the coil packs to make only one of them not work? what can i check and test? aren't they directly controlled by the ecu? would a faulty ecu cause this?
thanks!

Have you checked the associated power transistor?

http://www.dsmtuners.com/forums/showthread.php?t=229419&highlight=power+transistors

donmagicjuan said:

Have you checked the associated power transistor?

http://www.dsmtuners.com/forums/showthread.php?t=229419&highlight=power+transistors

Click to expand...

the power transistor is located next to the coil packs right? mounted vertically on the intake plenum? i also swapped this with another from a running car just to eliminate it as the problem...

Yes, that's it. If that didn't fix it, I would say you're looking at a continuity issue or a failed ECU.

donmagicjuan said:

Yes, that's it. If that didn't fix it, I would say you're looking at a continuity issue or a failed ECU.

Click to expand...

that's kind of the conclusion i'm coming to... i might swap in another ecu to see if that fixes it.

Lucky you to have another one lying around! In that case, I hope that it does. Trying to find wiring faults can be such a headache...

well, just put in known good cas... still no good!
so far i have put in known good
1.coil pack
2.transistor
3.ecu
4.cas

i still have no spark on 2/3.

any other ideas?
i can check for voltage from the ecu at the ecu pin 55 right? what V should i be seeing if it's functioning properly?
where does it go from there?
can someone give me a power flow diagram that i can trace with a dvom?

thanks!

Based on my interpretation of the diagrams I found and the information in the test procedure for the power transistor, you should be able to see continuity from pin 55 at your ECU to pin 2 on the 8-pin transistor plug. This is the line to the base of the transistor. I know that on mine the wire colors at these two locations match, which further supports the idea (brown w/ red stripe). Yours should both be yellow w/ red stripe.

Good luck and let me know what you find!

donmagicjuan said:

Based on my interpretation of the diagrams I found and the information in the test procedure for the power transistor, you should be able to see continuity from pin 55 at your ECU to pin 2 on the 8-pin transistor plug. This is the line to the base of the transistor. I know that on mine the wire colors at these two locations match, which further supports the idea (brown w/ red stripe). Yours should both be yellow w/ red stripe.

Good luck and let me know what you find!

Click to expand...

excellent! thanks a lot. i'll update after i test.

what about before the ecu? what does it need to fire the 2/3 coil? something from the cas right?

Yes, but you said you got a CEL for the ignition coil, right? My bet is that the problem isn't with the CAS or its wiring, since you don't have any problems with cylinders 1/4.

donmagicjuan said:

Yes, but you said you got a CEL for the ignition coil, right? My bet is that the problem isn't with the CAS or its wiring, since you don't have any problems with cylinders 1/4.

Click to expand...

yeah that makes sense. after some research on this and other boards some people siad they had the smae problem that was solved with a cas so i thought i'd try it.

terminaltsi said:

excellent! thanks a lot. i'll update after i test.

Click to expand...

i checked the wire, no continuity! for reference i also checked the wire for cyl. 1/4. all good.
so i spliced in a wire and fired it up, runs great!
thanks for the help!
i'd give you some rep, but can't see how...

Awesome, glad to hear your problem was pretty simple to fix. As for the rep, you just click on the little scales icon under someone's username by their post.