Would a dodgy spark plug cause intermittent misfire?

Discussion in 'Mech Tech' started by Dr Ben, Dec 10, 2012.

  1. Hi

    The van 1600 with 34 ICTs runs really well mostly! However sometimes it idles sort of lumpy and seems to be missing on a cylinder (when disconnecting leads to find out which one I stopped after electrocuting myself!)

    Then other times it is running brilliantly!

    Would a dodgy spark plug cause this? The dizzy (points now as gave up with rubbish elecronic ignition modules), tappets, leads and fuel are all ok I think and it was a new coil recently.

    Thanks
    Ben

    I will change the plugs anyway but just wondered if I need to look elsewhere
     
  2. I'd check your points as starting point.
     
  3. matty

    matty Supporter

    If its only one it could be the plug, lead or cap i have had bad brand new ones of each
     
  4. mikedjames

    mikedjames Supporter

    If you got zapped holding one of the leads, suspect it as this means there is leakage through the insulation or tracking across the insulation.

    If on the other hand the spark came off the end of the lead direct to your hand.... Its probably OK.
     
  5. Worn dizzy cam,?
     
  6. PIE

    PIE

    I would stick a timing gun on each lead one at a time then start swapping things around, leads ect, till you isolate it, every time I have had this prob it has turned out to be the dizzy cap cracked.
     
  7. The dizzy is fairly new vac advance, I got zapped where the spark went to the block and I was leaning on the bumper!

    Would there be no flash of he timing light on the affected lead if it was the plug?

    Hmmmm, dizzy cap... cant see any cracks. I think I will just get a new set of leads and plugs and points, cap and rotor arm and see how I go!

    Cheers
    Ben
     
  8. PIE

    PIE

     
  9. Ok thank you
     

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