QuestionQUESTION: I have a 2004 neon and I am only getting spark to numbers 2 and 3 cylinders. The car runs but 1 and 4 are not firing. I have replaced the coil, cam sensor, crank sensor, pcm, plugs and wires. I have tested the resistance in all of the wires going from the pcm to the coil and cam sensor. They all check out ok. I tested each cylinder with the same spark plug and wire. only sparking on 2 and 3. Any ideas???
ANSWER: Hi Ed,
A couple of suggestions:
Have you tried to get fault codes using the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window to see if the miles reading changes to show 4-digit numbers preceded by a P. Let me know what they are. If you get an 0320 that would indicate an issue with the cam sensor signal. Let me know if you get something other than 1684 or 'done'.
Then you could also measure the cam and crank sensor signals using a voltmeter between the signal wire and the sensor ground wire, while you turn the engine over by hand with the ignition switch in the 'run' position. The cam signal should vary between 5 and 0.3V four times per two revolutions of the crank, and more frequesntly than that on the crank signal. You can tap into the wires using a fine straight pin.
A problem with the cam signal may be caused by a faulty magnet (since you already replaced the cam sensor proper, assuming that you torqued its screws to about 10 foot-pounds). The magnet might have a crack and if so, then two of the four plugs would fail to get their signal to fire because of a missing signal from the magnet/cam sensor interface. So replacing the magnet would be a good idea if you have a cam code or measured signal pulse absence.
Given that you have checked the wires and replaced the sensor, getting a code and checking the sensor signals would seem to be the way to go.
Roland
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---------- FOLLOW-UP ----------
QUESTION: O.K. I checked the voltage to the crank sensor and the cam sensor while the key was on. The result was that the voltage jumped between 2.5 and 5 volts several times between revolutions (it was hard to count and watch the meter at the same time). It seemed to be working fine. Before I did this test I checked for codes and the only one was a battery temp code- 517. After I finished the test I checked for codes again and got a 2302-ignition coil #1 secondary circuit-insufficient ionization. Any more clues??
Thanks, Ed
ANSWER: Hi Ed,
The first question I have is whether the voltage changed from 5 to 2.5v or from 5 to 0.25v? If the former, then we have an issue with the sensor in question that is doing that.
The code 2302 is just observing that there is no spark on half the coil, which you already know. The manual is not very insightful about the possibilities: bad coil, bad coil driver wiring, bad spark plug wire, or bad spark plug.
I do have a question though, if the problem had to do with one half the coil then I would think that the non-sparking plugs would by 1,3 or 2,4 (not 2,3 or 1,4). Are you sure you have the wires plugged into the towers in the correct order, because with the firing order 1,3,4,2 that is what would happen if half the coil were bad or the cam sensor was bad.
What is the history of this problem? Is there anything relevant there?
Those are my questions and thoughts at this time.
Roland
---------- FOLLOW-UP ----------
QUESTION: Sorry, the low voltage was .25v not 2.5. The original coil was marked with cylinder numbers so I know which wires plug into which cylinders plus the wires are too short to go anywhere else. there is no spark coming from the rear posts of the coil and they plug into 1 and 4 cylinders. This vehicle just decided not to start on Dec. 9th and I did some basic parts replacement then took it to a reputable mechanic and he concluded that it was probably the pcm and since it had to be programed by a dealer he suggested I take it to them.I was able to get a preprogramed pcm but that didn't fix it.
AnswerHi Ed,
Excuse me, I made an error on the pairings up of which cylinders won't spark if half the coil (or half the coil driver signals) doesn't work. I am left with only the possibility that the magnet for the cam sensor is bad of the sensor itself is not positioned properly. You said you thought the pulsing was too rapid to count and that would be true for the crank sensor. But the cam sensor has four mangnetic pole change interfaces so it should only pulse two times per revolution of the crankshaft. So take a look at the cam signal and see if that is indeed the case. Either more pulsing or less might throw off the pcm as it decides which coil winding it is supposed to be driving. Finally, the driver wire for 1,4 posts of the coil might be continuous but it could also be shorted to ground, so check out that possibility. The 'coil driver #1' is black/gray (which I assume drives plug 1,4) but check the other wire too just in case... I will be interested to learn the answer.
Roland
PS Please 'rate' my answer if you believe it is warranted. Thank you
