Inconsistant KR after plug swap

[GoonBong]

Hi guys.

So after having some NGK Iridium IX plugs installed by a shop and getting some misfiring and high KR, I ended up putting the old plugs back in myself (they looked pretty good) and doing the coil stretch mod as per How To: Ignition coil spring stretch mod - Mazdaspeed Forums

While the misfiring is gone, I'm still seeing a lot of mild KR (under 2) which I never used to get and the occasional KR in the 4's when punching it.

I'm wondering if anyone had an idea of what else could have been disturbed when they installed the plugs? Tune is by Lex at Stratified and has been knock free until then.

Cheers!

[Lachlan]

Plugs gapped properly? The NGK do not come properly gapped for our cars (and one of the old ones could easily have been damaged on removal). You can also put a bit of ETH in the tank to see if its real knock or mechanical.

[GoonBong]

Yeah the old ones were gapped at 0.7mm and hadn't been in the car a huge length of time. It just seemed a bit co-incidental that all this happens after a normal plug swap. A station near by has E-Flex, might pop a few litres in, see what happens.

[GoonBong]

FYI I put the old ones back in after the misfiring.

[Lachlan]

You checked the gap before you put them back in?

[GoonBong]

Sure did.

[Lachlan]

Hopefully its just a bad batch of fuel then. Do the rest of your logs (AFR, fuel pressure etc) look OK?

[GoonBong]

Yep, AFRs looked on point, HPFP actual above 1600, etc.