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Coil pack

Discussion in 'Generation 1 Prius Discussion' started by Gen1Prius, Dec 31, 2013.

  1. Gen1Prius

    Gen1Prius Junior Member

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    Does anybody know that when coil packs start to fail they will leave a black carbon film on the outside of the housing where the rubber boot and housing meet? I have been having a problem with the engine stalling since winter has started. It runs for about 30-45 seconds and stalls and I get the MIL light on and when I connect my scan tool, I get a P3191 (engine did not start) and one time a P0300 (random cylinder misfire). All four coil packs had this black residue in one spot on the plastic housing of the coil pack. Prior to me purchasing this car, I doubt that the plugs have been changed, so I changed them and that is when I discovered this black residue. I started the car today and again it ran for a few seconds and stalled with the P3191 fault code. I didn't see the P0300. Since coil packs aren't cheap and according to my Chilton's manual, Toyota doesn't publish either primary or secondary resistance specifications. Any suggestions? Thanks.
     
    #1 Gen1Prius, Dec 31, 2013
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The engine spins for 30 seconds because MG1 is spinning it, in an effort to start the engine. Then the hybrid vehicle ECU realizes that the engine is not going to start, and stops MG1. DTC P3191 is logged.

    The engine is not actually running during that period. If you doubt that, try pressing on the accelerator pedal to see if you can increase engine speed.

    To deal with this issue:

    1. Clean the spark igniters to get all dirt off the exterior.
    2. Inspect the spark igniters carefully, looking for cracking or burn marks in the plastic body. Make sure the wiring harness connector does not have corrosion within. Replace the igniters as needed.
    3. Clean the throttle body interior and throttle plate using the minimum possible amount of throttle body cleaner. Rotate the throttle plate shaft by hand to expose the bottom of the throttle plate. Do not contaminate the MAF sensor.

    If you do all of the above (especially #3), I believe you will find P3191 will go away.
     
    #2 Patrick Wong, Jan 1, 2014
  3. Britprius

    Britprius Senior Member

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    Incorrectly tightened spark plugs can cause soot on the igniters. For resistance values check all four against each other. Open or short circuits within the igniters will then be obvious.

    John (Brirprius)
     
    #3 Britprius, Jan 1, 2014
  4. ChapmanF

    ChapmanF Senior Member

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    Well, primary resistance specs would be kind of a tall order just because these are not just coils but integrated ignition modules that contain coils, so a meter on the input terminals would not be seeing anything as easy to describe as a coil with a resistance, but some sort of power transistor input stage (with a feedback signal). I guess nothing would stop them giving a secondary resistance anyway, but maybe they figure the tests and oscilloscope patterns they do give (DI-115 to DI-118) are more diagnostically accurate than a resistance test.

    There are specific DTCs for when the computer doesn't get the spark confirmation (IGF) pulses back from the modules. You're not getting those DTCs, but it's possible if you have a carbon pathway built up around the boot then the module could still be signalling that it generated a spark pulse ok, but the pulse is following the carbon path and not all getting where it's needed. If it's possible the carbon came first (that is, it isn't a result of module failure) then maybe cleaning it off well would lead to more reliable ignition?

    -Chap
     
    #4 ChapmanF, Jan 1, 2014
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