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Thread: Mgzt260 slight missfire

  1. #11
    just more wrinkle ! ceedy's Avatar
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    I had a really tiny and infrequent cough/misfure when first running, did all the normal bits, but in the end a new Throttle Position sensor cured it !!

    even though the old one tested out as ok electrically .


    Our Three bloo's, ZR105, ZT 260#50 , CDTI Auto ,now No1 Son has spoilt the set with a Firefrost 1.8T


  2. #12
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    Thanks all

    the coil packs are msd...the manifold was from summit racing so think it?s a genuine one

    been on race car today so will have a plug in tomorrow when I get chance

    doNt think it?s anything major just one of them niggley things I will get sorted in the end

    thanks for all your advice and will let you know how I get on

  3. #13
    Registered User Malcolmr's Avatar
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    Here are a couple of photos for you Rick. Welcome from downunder, by the way. You can see how filthy a "fit for life" fuel filter gets after 100,000kms when I last replaced mine. I have now bought two new ones from Byron Rowson (see the Facebook group) who manufactures various items to higher specs than OEM, so I'm now fit for two lives, if not more...

    Malcolm
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    VIN 206
    This is definitely not her car...

  4. #14
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    Thanks malcom I think it’s worth changing.....
    right I e delved a bit and plugged into it...it comes up multiple missfire under 1000rpm and missfire in cylinder 5.....

    my theory is as it’s had new msd coil pack and plugs...runs well 2000rpm I’d think it could be injector...and or throttle position sensor

    what’s the experts think

  5. #15
    Registered User SCP440's Avatar
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    Move the injector from 5 to another cylinder and see if the fault moves.

    Steve

  6. #16
    #829 called 'Olive' David's Avatar
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    After you try the injector move that Steve sensibly suggested, if that doesn't work, check the connection to the COP on #5. MSD's can be a tighter fit than the OEM COP's and not properly pushed home. Examine the COP for dampness (on and in the tube part), and ensure that the contact spring is properly seating on the spark plug terminal. Finally swap #5 COP and another in the same way as you did the injector. Peer down the plug hole and see if the plug insulator ceramic looks discolored or "different" to the others.

    David

  7. #17
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    Thanks steve and Dave.....sounds like the sort of thing I was going to check....sure I will sort it...might get all injectors cleaned but will swap cylinders....see if it changes...still a beast though and fancy the Accufab throttle conversion ��

  8. #18
    Registered User SCP440's Avatar
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    While you are at it move the coil pack and spark plug to other cylinders, it will not be the first time one of these have played up.

    Steve

  9. #19
    Registered User Malcolmr's Avatar
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    Quote Originally Posted by David View Post
    After you try the injector move that Steve sensibly suggested, if that doesn't work, check the connection to the COP on #5. MSD's can be a tighter fit than the OEM COP's and not properly pushed home. Examine the COP for dampness (on and in the tube part), and ensure that the contact spring is properly seating on the spark plug terminal. Finally swap #5 COP and another in the same way as you did the injector. Peer down the plug hole and see if the plug insulator ceramic looks discolored or "different" to the others.

    David
    After I replaced all my plugs recently after a persistent low revs misfire, old 206 was initially worse. The misfire was more frequent, especially under a light load at low revs. Then one day I was driving in normal traffic when the car gave a little surge as if someone had turned on a "go faster" switch and the misfire went away. Now the car goes like a rocket! I'm still looking for that switch, but I presume what happened was one of the COPs wasn't seating properly, as David mentions, until more driving and vibration moved it into position. I had great difficulty with cylinder 4 (I think that's no 4 - the rear one in the bank on the right hand side of the car). Very tricky getting the plug in and out and then pushing the COP back into place.

    Malcolm
    VIN 206
    This is definitely not her car...

  10. #20
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    Quote Originally Posted by Malcolmr View Post
    Very tricky getting the plug in and out and then pushing the COP back into place.
    Easy with the engine out
    Colin Ellis #456 It'll be alright in the end. If it's not alright, it's not the end

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