Spark plug colour / health
18 October 2005, 01:51 PM
#1
Spark plug colour / health
Apologies if needed - posted this in General, but I think this may be a better place for it.
Comments on health would be most appreciated.
From my 97 UK turbo with 98K miles
Only mod so far is a K&N filter.
MAF NOT been changed ever as far as I can tell
They are NGK PF6B plugs
They have done more than book recommended miles, but can't think just how many at the moment.
About to mod exhaust and will be doing a pre mod rolling road test for comparison. But want to know I'm healthy.
Thanks
18 October 2005, 04:44 PM
#2
Can't tell the condition of the plugs from that shot. Colour looks ok - but that only shows the mixture was ok at that very instant the engine was last run, if the engine was ran cold, they usually go black....sometimes the same happens if you thrashed it before removing them....it's not something you can depend on. Unless they are covered in oil 
But even then an oil burning engine can have "clean" plugs because the combustion burns off most of the oil (see 2 stroke engines ).
What else you need to look for is to see if the platinum on the tips is still there (I have found them missing on some plugs), or if the electrodes are worn and have the correct gapping.
Also check the base of each plug btween the ceramic and the threads for any pitting - a sign of a faulty plug lead/coil pack or a faulty spark plug causing the spark to bypass the plug.
Finally cheack for any cracks in the ceramic both on the top of the plug and the nose where the electrode is.
But even then an oil burning engine can have "clean" plugs because the combustion burns off most of the oil (see 2 stroke engines ).What else you need to look for is to see if the platinum on the tips is still there (I have found them missing on some plugs), or if the electrodes are worn and have the correct gapping.
Also check the base of each plug btween the ceramic and the threads for any pitting - a sign of a faulty plug lead/coil pack or a faulty spark plug causing the spark to bypass the plug.
Finally cheack for any cracks in the ceramic both on the top of the plug and the nose where the electrode is.
18 October 2005, 09:11 PM
#4
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Originally Posted by Erik
Subaru says 100 000km for OE sparks.
I change my IK22 every 30 000km.
I change my IK22 every 30 000km.
19 October 2005, 01:12 PM
#5
Originally Posted by Erik
Your engine looks be in good condition, no oil on your sparks or unburnt particulates.
On with the mods then
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