After thinking about it, my oem sparkplugs did last quite a long time compared to the Densos. Im going to order the NGK ILFR7H. I think these are stock heat range right? Are there 1 step colder version of these?

EDIT: NGK R7437-8 are the 1 step colder versions. fml $166/set. E85 430whp + NGK ILFR7H? Yes?

 

Well that's odd. When I did my first round of bolt-ons and got Mellon Tuned, he pointed me to the Denso IKH24's for my Evo 9 gapped at 20-22. Been running them ever since with no issues whatsoever. Set in my car now has around 14 track events with no issues at all.

 

Yeah that's why i'm a bit confused as well, because Bryan @ GST was the one who recommended them to me back in mid 2009 and i've been using them since without issue. Well, besides the fact that i've been changing them every 8-10k miles or so

 

I got a few issues. My engine is misfiring in piston #1 according to autozone diagnostic test. I just recently replaced my spark plus with autolites?? I think they are called, the guy said I didn't need to gap them. I threw away the old plugs like an idiot and didn't check the gap on them. I do know the said "JAPAN" across them and they were NGK's. I bought the car with all the mods and tuning already done. I'm new at this but am very willing to learn. I have an 2006 Evo 9 IX. The car is running very poorly compared to what it was. If I get NGK's but they are not the exact same ones, what Gap should I use, and will I have to get the car re-tuned for replacing the plugs? Also I need some advice on what to check on as far as why it's misfiring, any suggestions?

 

I use NGKBPR8ES plugs and change them every other race weekend. They are cheap and work fine.

 

If you know any Evo IX in the area, ask to test their plugs on the car to see if the situation gets better. That's a cheap and easy diagnosis. Otherwise, I highly recommend grabbing a set of OEM plugs from Mitsu. Also, no gapping needed with OEM plugs.

 

Those are copper, for VIII only, not IXs.

 

What Chu said but I'd ask your tuner what gap to use based on your mods, fuel type etc, and he/she should tell you. If your in the 300-400hp range ya use the OEM NGK's which are ILFR7H's. More info here: https://www.evolutionm.net/forums/ev...ead-plugs.html

 

I just bought some NGK's from autozone, they were iridium ones, a friend of mine also said try changing the plug wires and possibly the coils, it may fix the problem??? is that a good idea?? Has anyone else had a similar issue with their engine misfiring like this? It only misfires under boost, which I thought was weird... hmm

Also, in response to finding my tuner... yea that's going to be a bit impossible because the guy is in jail.. and i'm not going to go visit him to ask about his old car.. lmao that would be awkward. The car is pushing 409 HP according to the last AWD dyno I took it to in Marryville TN (www.fasttechautosports.com).

 

when i got my car, it had Denso iridium in it and was miss firing crazy under boost. then Chu told me to try oem NGK and everything was solved.

 

Depends on mileage on your car, but the wires and coils are unlikely fail...not that they don't. Aftermarket wires never gained popularity on these cars, so if you end up buying new ones, stick with OEM. There is a way to check the coils, but you'll need a volt meter to do it. If, however, you find your coils/wires are bad, it may be a good idea to consider an individual coil kit by SpoolinUp or the like. Again, start with new spark plugs and diagnose from there. Track down the issues before you go and replace all kinds of unnecessary things and waste money.

 

I had problems with Denso. The best plugs in my experience are the NGK. even today my HKS plugs are really NGK's just labeled as HKS... and of course i pay more for that.

 

dont you have the VIII guys for the spark plug prices???
I DOOOOOO!!!! BOOOOO!!!!

 

Rob, I edited your ESL speaking a$$! No, I don't hate them...I AM AN VIII GUY!

 

Seriously lol, he's prolly worse when he starts drinking

But ya I wouldn't go to visit jail either lol. I think at 409 with 93 octane? the popular gaps are listed on that page I linked earlier. However it is possible to have a bad coil, if you have a friend that'll let you borrow a coil for a pull or two that'd be best as well. I also have a spare set of coils here that never misfired if you want em PM me.