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Spark plug reading related to coilpack?

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  • Spark plug reading related to coilpack?

    Just took delivery of my wifes new Japanese spec mayfair about 3 weeks ago and has been a great car so far but something recentlly has got me wondering...

    The ignition system on her car is that of an MPI, yet is the SPI fuel injection system. AKA the TBi for the japanese market only... its a 98' and has been a very solid car.

    The coil pack from what i understand runs on a wasted spark system, so two plugs fire at the same time, cylinders 1 and 2, and 3 and 4 fire in pairs.... oddly when i was checking my plugs (NGK BPR6IEX, gapped at .85mm) to see that the are in good health i noticed that cylinders 1 and 2 are great and have a light brown appearance, but cylinders 3 and 4 are somewhat sooty and black in comparison...

    my question is, what are all the reasons that could cause this? I'm only thinking that the coil pack may be starting to go bad and the spark is weak on those two cylinders due to the coil pack design.

    I do have a spare coil pack, but don't want to waste it if i can trouble shoot elsewhere.

    Recently i went over the following and inspected and replaced some parts, some may be related to the situation, others not.

    all vacuum hoses were checked for cracks and tight and proper fitting, air leak checked and all flushed and cleaned with compressed air.
    check all the plugs, and fitted new HT leads
    fitted ITG air filter in the factory style design in the normal airbox
    replaced bushings in the upper engine brace and fitted a new ground wire. and added an additional ground wire.
    cleaned and flushed intake of any residues (wasn't real dirty)
    inspected fuel filter and appears new
    inspected fuel pressure regulator and injector, both appear in new


    i wonder if the car needs a valve rocker adjustment as it seems somewhat louder then other minis i've owned, not much... I've never done a valve adjustment on a mini before, only witnessed Chuck and James do it to my green mini, and don't recall the trick they did to get the valves to line up in order... i just know its

    .30 mm gaps on the feeler gauge

    Check No. 1 valve with No. 8 fully open.
    Check No. 3 valve with No. 6 fully open.
    Check No. 5 valve with No. 4 fully open.
    Check No. 2 valve with No. 7 fully open.
    Check No. 8 valve with No. 1 fully open.
    Check No. 6 valve with No. 3 fully open.
    Check No. 4 valve with No. 5 fully open.
    Check No. 7 valve with No. 2 fully open.

    according the the manual.


    I will try installing a new coil pack if nobody has any suggestions, but i don't want to waste my only spare if it might be something else.

    any ideas would be appreciated!

    hope to bring her new mini to one of the next mini meets (if we can ever make it on a tues) its tough for us.

  • #2
    Well, after posting on theminiforum, i got a few responses on this.... And apparently i've never been attentive enought to notice this is normal for minis due to the poor design on the engine. I guess all mini's do this? I'm tempted to pull the plugs on my green mini and inspect them too... the two center cylinders 3 and 4 are the somewhat sooty ones, anyone can confirm this is normal? 1 and 2 the outer cylinders are burning efficient and are light brown.


    • #3
      Now I've got to go and pull mine to see! Thanks for the insight.
      All Together Now..... Everybody.......