I just pulled out the sparkplugs after some driving so they were warm (NGK 1GR7A-G) and took some pictures of them. Since they, as far as i know, have not been replaced from new (47.000 kilometers) I replaced them for NGK Iridium IX BPR7EIX (all pre-gapped at 0.028 checked)together with Magnecor sparkplugwires (8mm). The plugs that came out look okay but a bit on the rich side I think?

Did i replace them with the right plugs?

It's a 2004 EVO VIII, Injen Intake with Upper and lower intercooler pipes, Cat back exhaust, Ecutek tune, and Saikou dual oil catch can. I received a Walbro 255 pump yesterday wich I will be putting in this week.

pictures of the old sparkplugs from left to right standing in front of the car.

 

they look like the right ones to me, you might run into misfire with those magnecors though, and you are going to need a retune when you install that 255.

 

Plugs look just like you would think after 40K Km with a little knock. #2 shows the most knock and you would think that since it has the shortest exhaust runner. #1 ran the coolest for some reason maybe by the same mechanism.

If you still have stock wires, use them. See if your knocking, if so, use better fuel or tune out some knock.

I keep forgetting those plugs are old so ?

 

I run BP Ultimate 99 RON the best pumpgas available here in the Netherlands. I have not noticed any knock only when i ran a quarter tank off Shell V-power because i had to fill up or push the car home and no BP around. The Shell ultimate is marketed as being 98 RON but it turns out it's 95 RON only.

The car is getting a dyno run at the end of this month. I wont be changing anything untill then so I have a starting point to go from. After that i will see what way to go, get some parts installed based on that and have it retuned and dyno again.

 

Must be from 40,000 km of use then . Glad you posted pics of heavily used plugs though, just backs up my theory that #2 seems to be the hottest and #1 the coldest.