My car has been playing up fair bit, missfire on idle is the lastest addition.

When i go WOT around 5-6k rpm it would just sound like antilag possbile fuel going into exhaust from missfire ? looses it momentum, jerks and pops lol. Doesn't happen all time but 2 out of 10times is not unusual.

is it possible for not having enough backpressure to cause missfire ?
i just have resonator and highflow cat no muffler stock Downpipe.
for some reason i never had these types of problems untill i got my HFC installed

ive had my car retuned today and they check sparkplugs and ect.. they cleared the code (P0300) and said it was all fine.. :S :S 30min later i gave it abit just to see how it goes and missfire has come back.
ive got those HKS plugs (gap is ok)

Ill do compression test tomorrow, might even test that fuel pump relay.

any ideas what else i should check? could it be injectors?

 

The HKS plugs need to be gapped around .022" to work right, any wider and I got an odd misfire at higher boost levels.

 

Ill check it out in morning, thanks buddy.
hope its something soo simple

 

HKS M40XL

Ceramic insulator has fallen over the electrode on one of the spark plugs, you can push it up and drops back down its f*cked only done 3,000ks others seem fine.

I have look at the gaps and its bigger then 0.028 and tad smaller then 0.032
do you recommend running 0.022 ? im preaty close to stock boost. Ill see how it goes with new plug then ill go from there.

 

Either that spark plug was defective or the ceramic insulator broke loose due to moderate detonation. Either way, I would switch back to stock plugs and triple-check that tune. There's absolutely nothing to gain with "trick" plugs like the HKS ones when we already have a COP ignition setup.

Good luck with getting that taken care of.

 

You guys gap these plugs when it says right on the box to not gap them because the center electrode is easily damaged? I didn't gap mine but I have a stock turbo, so...

Most of the stuff I've put on the car didn't result in gains. I think it looks purty on the mod list...right after the Okada plasma coils, which I didn't need.

 

In all fairness, spark plugs aren't really a good item to gamble with when choosing vanity mods. I love HKS stuff and it's great quality (the plugs are probably made by Denso or NGK anyway) but stock or at least stock application and a different heat range is always best when it comes to spark plugs.

I mean if you're running HKS plugs and having problems, it's definitely best IMHO to just go back to stock. There's nothing wrong with running stock plugs. I do realize they're expensive, but I'd gladly shell out the cash for OEM plugs when I know they work perfectly.

 

Typically the stock plugs on the stock turbo at stock boost are fine at .028" gap. Once you start going past 25 psi you might have to tighten them up but it's not so much the boost levels but the amount of airflow you are forcing into the engine. When I first switched to the HKS plugs (one heat range colder), they were fine at 25 psi on the stock turbo but would break up when the GT30 was installed. I lowered the gap to .024" and they were good to about 27 psi but past that I saw issues again so I dropped to .022" which has been fine at 30 psi on 100 unleaded so far.

I would also stick with stock if you are sticking at stock HP levels or not going past around 400 crank HP which is about the limit of the stock turbo.

I think the general rule is that you can start thinking about going one heat range colder than stock when you are about 100 crank HP higher than stock. When my stock turbo setup was maxxed out I was at around 400 crank HP, and now with the GT30 turbo I'm around 500 crank HP and the extra resistance to detonation should be beneficial assuming they aren't defective and are gapped right.

 

Tuner told me to upgrated spark plugs after the tune, because it was making bit more power and i had few missfire issues with stock ones.
Once we put HKS in it was a dream untill not soo long where it would miss fire on WOT once in while, it got worse to missfire on idle.

this was the dyno graph i got while one sparks was stuffing up still

 

I have the HKS M40XL's but I just put them in and I didn't gap them, per the instructions on the box. The tuner got all of the power out of my car that could be expected without more mods.

I don't think they helped or hindered anything. The plugs cost more than the stock plugs (I think $17 vs $23 each). The stockers were looking rather nasty after 3k miles on the stock tune so I swapped them out before my tune.

 

Good info, thanks. The Okadas are designed to allow you to run a larger gap and I'm also running 25psi on the stock turbo. When I upgrade turbos I'll be sure to throw in new plugs and check the gap.

 

yeah , the instruction on the HKS spark plug said do not gap this spark plug..
interesting at least.

 

Replaced one of the plugs it pulls alot harder now very nice but i still have missfire issue around 5-6k rpm. Stock HKS plugs gap is better then .028! should i drop it down. On box it does say not to gap it.

I might buy some stock plugs tomorrow and see how they go, anyone know gap on stock plugs ?

 

Stock gap info:

Standard value: 0.5 − 0.6 mm (0.020 − 0.023 inch)
Limit: 0.75mm (0.029 inch)

You're fine to regap the HKS plugs if you are only closing the gap. It says not to regap because they don't want you using a spark plug gauge to open the gap and potentially break the center electrode. If you have to reopen the gap, use small needle-nose pliers to pull up on the back of the ground strap. I'd gap them to factory spec, honestly.

 

thanks =)


When for drive last nite and one of the plugs **** it selfs same cylinder, ceramic bit fell off (new plug 100km's on it.)

would getting Okada Projects ignition coil packs help ? :S
Australia is soo crap i have to wait a week for stock plugs bS!.