A.Wayne

That cylinder is burning oil , adding oil to the mix will cause the cylinder to detonate , the plug shows detonation , rich on the top leaner on the bottom and mid. Stick a new plug in their use a no 6 not 7 and run it again pull the plug and look , there is too much mileage on that plug. to use as a good reading tool , a newer plug will give a better idea as to the condition of the cylinder ....

blown 944

Actually it would be better to swap to #3 as it is on the other injector driver circuit.

However my opinion is that it is probably due to your extended time away and possible a small leak in that valve guide.

I would just change the plugs and pull them after some hard runs and then post up what they look like both a good plug and the bad (if it continues to be bad, I doubt it)

Also the AF gauge will not be able to tell you anything about one cylinder, but it is very valuable for making sure you are at a safe ratio. So yes you NEED one especially if you plan on runnign at these pressures regularly.

Darwantae951

LA- ART

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Darwantae951

Someone care to explain spark plug temperature ranges?

Keithr726

HAHA ^ #18

blown 944

The hotter the spark plug the further the electrode sticks into the combustion chamber. example: 5 = hot ....... 9 = cold. colder plugs have the electrode barely protruding out of the threaded area to dissapate the heat quickly

the hotter plugs will burn off any carbon easier for regular street driven type cars

However, if you run too hot a plug in a boosted or High HP engine the electrode will stay hot and may detonate (pre ignite) this is very bad. Hence the reason why when running a highly modded car you need to use colder and change plugs more often.

the "R" is for resistor for interferance

Darwantae951

Thanks for explaining that!

Darwantae951

If what I just learned is right, wouldn't these two plugs be in the same temp range?

blown 944

Yes they are the same heat range just different companies

Jeremy Himsel

No the NGK's numbers work differently the bosch or champion. The colder Bosch would be a WR6DC and the stock NGK 951 plug is a BPR6ES with the 7ES being one rangecolder. Japanese?

Darwantae951

I'll try them out after I used this set of Bosch plugs.

blown 944

Is that true?? I have only used NGK in racing apps and never paid attention to the stock plugs In any car. But that would be completely backwards

If I am incorrect I apologize.

I must research this ............

hosrom_951

I agree, the NGKS made the car smoother and always came out in a tan colour.

Change that plug, after 100 miles or so, check it (as mentioned earlier).

blown 944

edit...I am incorrect on the heat range between bosch and champion compared to NGK. They are indeed bassakwards.

Boy...... it's a damn good thing I have never strayed from NGK all these years.

Jeremy Himsel

With american plug makers Autolite, Champion (Bosch included), if it's a higher number it's a hotter plug. Japanese manufacturers like Denso and NGK if it's a higher number it's a colder plug. If you're turning up boost pressure from stock it's a good idea to go one range colder within a + 100HP window.

The 6Es is the stock plug in the NGK, the 7Dc is the stock Bosch.