Edmunds Answers


  • zaken1 03/02/11 8:07 pm PST

    The ignition coil would kill 2 plugs if it went bad (UNLESS A SHORT TO GROUND DEVELOPED IN THE COIL RIGHT NEXT TO THE CONNECTOR FOR THE # 2 CYLINDER PLUG WIRE. Then it would only stop the spark to # 2 cylinder). Sometimes an engine can miss on two different cylinders, but may sound like it only misses on one. If you could exchange the position of the two plug wires on that coil section (the two connectors which are straight across from each other); you could see whether the # 2 cylinder still is the one that is bad; or whether the problem has moved to the other cylinder.

    My suspicion is that this is either a compression problem, or the fuel injector for the # 2 cylinder has stopped working. If a cylinder has low compression, or the injector is not supplying fuel; the spark to that cylinder can look very different from the other cylinder. I also don't know how you connected the spark detector, or what kind of device it is; but there may have been a problem with the way you used it.

    The first thing I would do is to test the compression in cyl # 2. If it is less that 135 psi; there is a mechanical problem in that cylinder (blown head gasket, broken piston, or burned or stuck valves). If the compression is good; I would test the power wire to the # 2 fuel injector for trigger pulses with a 'noid light (which can be bought or rented from most parts stores). If there are no trigger pulses to the # 2 cylinder injector; the injector wiring harness must be tested and repaired. If there are trigger pulses to that injector; replace the fuel injector for that cylinder.

  • ralka 03/02/11 10:04 pm PST

    the spark detector i have is just a hand held pen like device with a section beveled out to put on the wire. it lights up when you rev up the motor a little. (nothing fancy) i will check compression tomorrow. i did swap 2 of the wires but not with the one in the rear on the same coil pack, (same result)

    thanks for the help

  • zaken1 03/03/11 12:47 am PST

    Thanks for the feedback. Those inductive spark detectors can be fooled by compression or mixture problems; so I would not assume there is no spark on that side of the coil. The only sure way to test a plug wire is by measuring its resistance with an ohmmeter. There should be less than 1,000 ohms resistance for each inch of wire length; so a 15 inch long wire should have less than 15,000 ohms total resistance. Be sure the meter probes touch the metal terminals at each end of the wire; this means you'll probably have to insert one probe into the spark plug boot to reach the metal terminal.

    But when I mentioned switching the plug wire positions on the coil; I did not mean to exchange the whole # 2 cylinder wire with another one. What I meant was to leave all the wires connected to their respective spark plugs; and to just exchange the position of the coil ends of the two wires on the coil pack that feeds # 2 cylinder. It is OK to do that; because the two cylinders connected to that coil both fire at the same time, so there will be no change created in the firing order or the timing by switching the coil ends of those two wires. The purpose of this test would be to see if there is a problem on one side of that coil; not to test the wires.

  • ralka 03/05/11 7:12 pm PST

    thank you for all the info and advice , i replaced the coil pack and that solved the problem

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