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problems of spark plug fouling and misfires

Pete Lewis

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Aidan posted this article about the problems many have with plug fouling and never returning to fire correctly often at low life

this goes into   thoughts of the ceramic becoming contaminated  which has some credible  overtones


then Andy one of my locals suggested we read this


and after a few pages i lost the will to live

have a browse at all these and see what you make of an increase in reliable spark plugs becoming unreliable

the choice is yours 

have fun 


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I have found over the last three years or so that NGK plugs fail all too quickly - less than a 1000 miles use.

Once misfires start the plug can;t be retrieved .

My symptoms were - slowing down for a tight bend to apprx 10/15MPH come round corner and exit with a slight incline. Put foot down in 2nd gear and it misses badly. 

OK at speed.

Plug life no more than 1000 miles.

Changed to Champion L87Y and they have easily done 5000 without a miss.

Many of the TR fraternity have had similar issues with NGK.



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Notwithstanding all the technical stuff in Pete's articles you only have to search 'Fake NGK Spark Plugs' as a starter to this widespread issue.  However, this is not a new thing; Mark Fields (Jigsaw Racing) warned me of this 10 years ago and his suggestion then was 'look for the Made in Japan'.  Not sure if this still holds true.

I have had no issues with NGK in my GT6 from (re)build but I also but from my local car factors and not from the 'great value/cheap/unwanted stock/etc' on EBay.  If it's notably cheaper than rrp than there is probably/possibly a reason.


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Maybe I should have linked the two subjects together would have made sense , but hey ho,

I have used champs and ngk for all my life and myself have not had a problem ever , I dont run on choke and keep things in tune so I dont get any sooty plug syndromes, but I have some local  cars that can run rich or do short runs so never get a italian clean up

One local mkiv spity does a commute 2mile run and is in regular plug fail troubles.

The unglazed plug insulator and 22kv ht makes sense to this car

We cant up the HT much without invoking dizzy cap and rotor failures , and there been enough of them over the years  coupled with duff condensers our std ignition is on its limit including bypassed 1.5 ohm coils ( doubles the ht and amps at the points) blowing points and condensers   and  tne  duff aftermarket parts we are supposed to accept.


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I have used NGK BP5ES for many years, but I did find the 6's fouled on the PI cars sometimes.

Had one PI that would oil and or soot up the 5's so I have tried some 3-prong Bosch ones recommended by Nick Jones. They seem fairly immune to the PI cars.

I have always managed to recover the fouled NGK by wire brushing and cleaning off with thinners.

then cook the end over a gas ring. 

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I’ve had the NGK fouling issue and written of it before.

My PI, in the days when it was still Lucas PI was a great killer of NGKs. I don’t think fake ones as they came from my favourite motor factor, not the internet. It killed a nearly new set of 6, one by one due to flooding caused by TB balance issues. They just couldn’t be got wet. Once fuel wetted they were dead and couldn’t be recovered by cleaning or even cooking with a blow lamp (which I’ve never know fail before). I replaced them, one by one, with scabby old NGKs of the same heat range which though they didn’t work well wet, could be recovered by cleaning and cooking. This answered a long previous mystery as to why a complete set of nearly new NGKs had died in our long departed Nissan Primera GT after I’d inadvertently flooded it after failing to reconnect the coil pack. Took me bloody ages to unscramble that one!

Bosch ones, especially the 3 prong ones, seem pretty resistant to fouling and are certainly recoverable after flooding.


Not on commission from Bosch btw, mores the pity!

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