I am currently running the stock plugs but do have some colder Zex plugs. I tried installing them at 4k (milage) but when it hits boost, the car kinda shakes a little so I switched them back. Yes I installed them correctly) Someone told me that I should wait until atleast 10000 miles before I change my plugs. I was hoping to get ppl's opinions about this.

 

Honestly dude you can change your plugs anytime you want but I don't have any experience with those I have no idea what type or what history they have in the 4g63. I have tryed the Denso IW24's and the NGK BPR7ES and I feel that the NGK work better than the Denso's even though the NGK are copper. They ran cooler EGT's and seem to preform just as well if not better and they are only 12 bucks a set compaird to 55 for the Denso's. I am not stock but I am only runny 19-20 psi on 93 oct. Under more boost the Denso's would probably be worth the money gapped correctly. The only advise I could give is double check the heat range and gap.

Anyone else have any Ideas?

Maybe post a pic of the Zex plug by the Stock NGK

 

Off to the Engine tech forum.....

 

That definitely sounds like the gap on your plugs are off. I know with the stock plugs the gap is about 0.028. I am running the Denso IW24's with a 0.027 gap. That is the gap I got them at and they work fine. I also bought some Ngk bpr7es' gapped to 0.028 that I will be throwing in just to compare the two. So far right now the only difference that I can see is that the iridium plugs would last longer than the copper ones.

 

I prefer teh NGK...I ran the DEnso and they are crap. They fouled up so quickly. Intsalled the NGKs with the same gap and my EVO ran like a beast. At $2 a pop u cant go wrong.

 

If I were to go with the NGK, what would I get and where would I get them?

 

Pretty much any auto parts store will carry them. Just ask them for the NGK BPR7ES. These are the copper ones unlike the iridium NGK's that came with the car stock. They are the same heat range though. Also, Buschur runs the BPR7ES on there evo and I would say that there car runs strong.

My denso's still look good. The fouling is mostly due to the fact that the evo runs so rich to begin with. My stock plugs fouled up quickly also from this.

 

The NGK BPR7Es also has an iridium version BPR7EIX, but cost 3 times as much. I prefer the copper since I rather run a new set of plugs every 5 - 7k miles.

 

Just ask for stock #2023. Double check the gap when you get them, but mine are typically .028

 

I run the Denso's one step cooler than stock.. Have had good results with them under higher boost.. occasionally on cold days I get a bit of misfire that goes away when it warms up. Everyone has different experiences so its a matter of trying different products. But I run a .026 gap.. I run higher than stock boost, and get no misfire whatsoever (probably due to the plugs AND the tighter gap) The one thing I did notice was idle was much smoother when the car was warmed up, and the car became alot less knock-prone when tuning.

The NGK's are certainly a more cost effective alternative and the cooler heat range should be good for the same gains.

 

So, are there any benefits to running the iridium NGKs over the copper ones?

 

Yes the iridium ones will last longer and can take more abuse at higher boost levels with correct gapping.

 

Does any one know what size socket it takes to remove the stock plugs?

 

I believe it is the 13/16's off the top of my head. The largest size in the set.

 

here we are again back on the spark plug thing. This has been discussed to death and it is funny hearing someone say that the Denso's are crap HAHA..evojim do you have any data to support such a comment. I will tell this, I went to a range colder Denso from z1auto and I did datalogging on the timing advance and with the range colder denso timing was not pulling as much at WOT 21psi @ around 6-7Krpm @ around 12-14 degrees vs 7-9 with the stock NGK. If you also look at a chart of the properties of iridium vs copper, there is no comparison....from MachV web http://www.machv.com/denirsparplu.html

you can also purchase them from z1auto for cheaper