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Thread: What happens if a spark plug is not firing?

  1. #1
    Bimminator Guest

    Default What happens if a spark plug is not firing?

    Got down to see Bruno on Sat. finally and got some parts and good info. You may remember my last couple of posts have been inquiring about some tranny problems I'm having. After a reset over a week and half ago, the car has been running good. No problems down to Bruno's and back, Well now today the car won't shift past 3rd gear again!!!!! It holds in 2nd for a ridiculously long time and then goes into 3rd, I think, or assume as the needle on the tach finally drops a bit, but there is almost no audible indication that it has gone into third. I told Bruno what had been going on and he thought it sounded like the car was locked in sport mode. I was thinking tonight, what about that one badly cross threaded spark plug I have (some of you may recall that post as well). What would happen if that plug was pooched and not firing? Would the car even run? I'm not sure what to do next with this car, should I be looking for a good automotive electrician, or should I keep looking for a tranny guy, as the couple that I have talked to already don't seem to keen on tackling the problem. If this is a solenoid issue, would a rebuilt come with its' own solenoids or are they seperate from the tranny?
    Any thoughts would be greatly appreciated, sorry for the wordy post.

  2. #2
    Join Date
    Nov 2004
    Location
    Gateshead,UK
    Posts
    926

    Default

    Sorry can't help with the gearchange - maybe there's a vacuum leak somewhere? I can help with the spark plug issue though - You've got a serious problem there as that plug could blow out of it's hole and punch a dent in the bonnet, maybe causing a small fire. Is your engine misfiring? If you remove the HT lead from that plug and stick another plug in there and earth it on the rocker cover or exhaust manifold you should see the plug 'firing'. If there's no spark then check the HT lead & dizzy cap.
    I had a similar thing happen on an old motorbike I had, with a cross-threaded plug. Tried to start the bike, engine fired up and POP - the plug shot across the garden at a million miles an hour!

    Hope that helps

    Shaun
    Last edited by E34-520iSE; 07-20-2005 at 02:05 AM.

  3. #3
    Join Date
    Jan 2004
    Posts
    296

    Default

    Also your engine would be running rough if one plug is not firing.

    To test it, pull off the spark plug wire from the suspect plug and start it up. It should run much worse, if there is no change, then that plug isn't firing.
    DanH
    1989 535iA 254k Miles
    1992 535iM 330k Miles

  4. #4
    Bimminator Guest

    Default

    Quote Originally Posted by DanH
    Also your engine would be running rough if one plug is not firing.

    To test it, pull off the spark plug wire from the suspect plug and start it up. It should run much worse, if there is no change, then that plug isn't firing.
    Thanks for the info, I think it is firing but I will pull the wire off tonight just to see.

  5. #5
    Join Date
    Jul 2005
    Location
    Kent England
    Posts
    3

    Default

    you need to replace your Automatic Transmisson oil

  6. #6
    Join Date
    Dec 2003
    Location
    Eastern Tennessee USi
    Posts
    14,679

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    does the engine run rough?

    Reboot the computers and try again.
    95 E34 530I V2.31
    ===========
    Those who make peaceful revolution impossible will make violent revolution inevitable.

    John F. Kennedy

  7. #7
    Join Date
    Dec 2003
    Location
    Toronto
    Posts
    159

    Default Go down to Toronto Transmission and get them

    to check it out for you. They know these cars inside out (german specialists) and I am sure that they can diagnose the problem for you. They are the only ones that touch my tranny when it comes to fluid changes. Very honest and reasonbly priced. They are on the web. Google them and you will get their details.

    Brian

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