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I started having P0300 misfire codes some time ago and narrowed it to a faulty coil pack. The car ran well after that for a few months and then it appeared again. Strangely, if I continued to drive with the misfire, it would intermittently go away and full power would be restored for a short time, then it would begin to misfire again. It seems the coil packs are consistently burning out but I’m unable to trace any electrical problems. I’ve started again at the packs themselves and verified no resistance across the pins thus verifying two of the four packs are fried again. No noticeable overheating or bulging, wires appear in good condition with good continuity checks.
Next on my list is the ignition condenser ohm check but the FSM doesn’t list a rating. Is an ohm rating “Except 0” acceptable for a condenser or should I be concerned with the reading?
I’ve read on many forums these Nissan (Hitachi /Hanshin) coils are susceptible to failure quite often. Is there anything that would consistently cause these to fail other than bad design?
Did you check for carbon tracking on the plugs and wires/boots?
Is the problem constant? Engine hot/cold, weather related/high humidity?
A good condenser/capacitor will have an infinite resistance when it is fully charged. I’m thinking the value of one is pretty small and you cannot check it with a VOM.
The best thing to use would be an capacitor checker with an ESR function. However it’s probably easier and cheaper to just replace the capacitor.
i suspect this coil on plug design might have the transistor built into the coil pack
id be curious if the wireing is truley ok all the time. Id suspect it could pull down and zap the transistor at times. Id make sure motor mounts ok and wiggle test harness. Inspect high probable areas harness could be chaffed or being pulled.Also where are you getting the parts ?
an old saying is New does not mean Good.
However at some point you have to trust the part….agreed.
Hey guys. Thanks for the replies. Kind of forgot about the place. Opps.
Still having this issue but it’s getting more weird.
Correct, this is COP.
Ran through full fsm diagnostics and everything checks out. Continuity, coils have resistance “except 0 and infinity”. There are some exposed coil plug wires but appear to be in good condition. Tried the wiggle and nothing changed.unplugged while running to verify spark and no change.
The weird part is the only coil not firing is the #2. If I moved the coil to another cylinder it works fine. The #2 plug looks ok, continuity on the wires looks good, new crank/cam sensors. Their wiring looks good and checks out.I’m at a total loss why only the #2 would not fire. It uses a common grounding circuit for all of the coils through the ECU so if the sensor or ground were damaged none of them would fire. I thought it may come down to the ECU but I had a spare and tried it and #2 remains elusive. Gonna start looking at harness repair, try to run new leads and see if maybe they are indeed damaged.
Any other ideas greatly appreciated.
getting down to the nitty gritty. bypassed the main harness with new wires and i’m getting signal directly out of the ecu on the test lead and also through the main harness at the connector to verify the wire wasn’t bad, tried swapping the coil to another cylinder again and it’s not firing. I think conclusion is coil pack. I’ve ordered a new one and will update on Friday! The most recent video about ignition coil testing showed using the led test light, this helped me verify the signal wire was indeed firing off. instead of firing the parts cannon, i’m firing the tools cannon! thanks Matt!
I’ve also ordered new connectors and wire leads to redo the ignition harness to repair the exposed ends.
Sometimes the solution is so simple that it can be overlooked – you have not said that you moved the #2 spark plug to another location (cylinder) to see if the missfire moved right along with the plug. If you have not tried this, do so, the cost is zero. The plug is an intedgral part of the circuit and needs to be checked………….
Hey Nash
thanks for the reply. I failed to mention it but I did indeed try that. I got the new coil and it fired right up on all 4. All good now! Bad luck i guess with the 3 test coils I had must not be good either. I removed the pins from the connector and taped the exposed wires just in case the signal was somehow arcing to the other exposed wires.
Success!
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