I took a plug out of my sti4 at the weekend. It was a NGK PFR6B and was gapped at 0.8mm.

I done a search on here and it seems they should be PFR7B with a gap of 0.7mm.

Will this cause any problems with running or wear and tear etc ? Should I have them changed asap or will I be able to wait until the next service ? Car has 42k on the clock, last change 30k.

Thanks

Ken

 

I didn't think the STI required 7's as standard. Moving to the 7 is a good idea anyway, as it is a slightly colder plug. I don't think you should really need to drop the gap so much if you are having no running problems with the 0.8mm gap on the 6s. OE plug gap spec for UK 97/98 at least is 0.8mm to 0.7mm .

 

Thanks Moray

I'm having some running problems, hesitating a bit, revs up and down a bit particularly when cold, seems lumpy at idle, surges a bit.

It has just had a new oxygen sensor and a ecu reset, was the same before except it didn't surge.

I only checked the one plug so can't be sure what the others are like. It was a browny orange colour.

Ken