my STi 6 now has 23 000Km and still runs on its original plugs. i really don't drive it often (once a week) but i noticed a very subtle ping between 3000 and 4000 while coasting, it goes away when uder any amount of boot. this, i think, is because the computer goes into fuel enrichment and ignition retard mode when boost comes in, which makes me think that the plugs could be ageing.

any thoughts ?

 

seriously, nobody has a clue about this ?

 

A ping? On very small throttle opening?
Doesn't sound like det to me...

 

an i run 98ron all the time.

 

Could be ... highest egt's are recorded on light throttlke cruiseing. If the plug is overheating its very possible.
NGK platinum plugs are supposed to do 30,000 miles but would suggest a change every 10-15,000 as routine.

 

thanks Bob, it's always good to have some advice from someone with a reputation.