Misfire under load

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- Tunku
  
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posted
14 years ago

Sat, Jun 20, 2009 10:46 AM

"Mrcheerful" wrote in news:hgK_l.44587$ snipped-for-privacy@text.news.virginmedia.com:

I seem to have fixed it. I kept going back to the idea it was leads plugs or coil pack. It had the same problem with two coil packs and another set of leads. I took the plugs out as a last shot. Remember these were new Motorcraft parts. The first thing I noticed was a black line down the side of the insulator on one plug. I cleaned this off and inspected the other plugs. All clean. Went for a road test and everything is fine, no more low speed misfire or full throttle hesitation. I'm happy again - many thanks to all. Just one thing, is silicon grease on the plugs and lead ends a good idea?

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- Mrcheerful
  
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posted
14 years ago

Sat, Jun 20, 2009 2:42 PM

nothing at all, anything that can trap dirt will give a path to track ht along.

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- Dave Baker
  
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posted
14 years ago

Sat, Jun 20, 2009 3:24 PM

No. Just clean and dry ought to do it. Also check that there isn't any oil or grease or other muck inside your spark plug socket which could get on the new parts and provide a path for current tracking.

I think everyone who's tried to find an engine fault has been caught out at some time by the assumption that the fault can't lie in new parts or that they don't need checking again. Someone in the archives in here is my 2 month saga of trying to find out why an old VW Polo I'd borrowed kept cutting out - usually in the fast lane of a motorway or dual carriageway much to my chagrin. I stripped and checked everything except the fuel filter which I'd been told had just been changed but it finally turned out this was already blocked again by rust from the fuel tank.

30 years ago I had a Honda 550 motorbike which had a very slight hesitation or splutter just off idle. Nothing to worry about but in the search for perfection I balanced the carbs, adjusted mixtures, reset the points, tried a new set of Champion plugs to replace the old ones but nothing fixed it. I tried a set of the NGK equivalent plugs and it disappeared completely never to return. I've been rather partial to NGKs ever since.