This is the second set of NGK Iridium IX plugs I've tried in my Max and have had problems with. Rough idle & slight miss, made somewhat better with setting proper gap, but still worse than the oe plugs I threw out. I'm thinking about pulling them again and going in favor of the cheap V-power. Would go platinum, but have heard good things about the v-powers. Considering the minimal expense and ease of replacement (25-30K), it seems logical to give them a try. Anyone have problems with the iridium IX or have recommendations for the v-power?

 

just go with the Platinum, you are better off.

 

from what I hear, as well as oe recommendation the platinum are best. but coppers should be decent if changed regularly i would think

 

Try the coppers just to see if it corrects the problem. If not, you haven't spent hardly anything in plugs

 

v-powers are pretty good, i got that in my car at the moment,

-Moo

 

I have coppers in mine. They're dirt cheap and you get what you pay for. At idle, I can feel the odd skip ever so slightly, but it's there. The platinums are great too but my last set started to rust prematurely around the base.

Why not try the v-power? Might be a gimic... but if they work fine, who cares?

 

I guess I'll give them a try.

 

i have iridiums in my car and it runs great..pepboys has them for 9 bucks each

 

You have a 99...

Your problem isn't with spark plugs, it's your coils that are causing your problems. Stop playing around with the plugs and look at whats causing them to misfire.

Most 99's on here, myself included have had the same symptoms you describe all fixed by replacing the coils.

 

I had a problem with the coils that was taken care of before this. I bought one front and one rear. Swapped them around until I found the bad coils. Car ran fine after that. A week or so later, I put the new plugs in and noticed the problems. Other than the iridium plugs somehow heating up and ruining the coil(s), it seems more likely to be the plugs.

 

Check the gap. Maybe consider making them on the low side of normal.

I was in the same position as you though--albeit with Denso Iridiums. After only 12k miles or so, the car starts misfiring! Replaced them with coppers and all was well again. I didn't check the gap though and the plugs themselves looked fine--I just didn't want to mess with them.

 

I also have the Iridium IX in my car and have not had any problems.

 

he's right. seems like the rest of your coils are going bad. change the remaining bad coils

 

I reall hope it isn't the rest of the coils going bad. I'll try changing out the plugs one more damn time. I'll take the advice and gap on the small side of normal at about .040-.041. I believe that there are slightly better results at such gap than the recommended .044. Besides, gap does widen during the life of the plugs, so it would be wise to anticipate it. Hope it is cleared up with plugs, hate playing one mississippi two mississippi with the coils. Thanks

 

Seriously, it's not the gap.. It's your coils

 

I don't know why people like to do things differently? First of all, has anyone done a dyno, before and after they installed "NGK Iridium IX plugs" on their Maxima? Can someone show me that? I like to know if there is a difference? I like to know the same thing with those cheap Crap copper plugs. Can someone show me a before and after dyno with those two spark plugs, and tell me if there is a performance gain or loss, or everything is the same.
Why not go with the factory spec? "NGK Platinum" If you are going to buy NGK Iridium IX plugs? And don't tell me you don't have 66 bucks to invest into the NGK Platinum spark plugs? For what I read, some people are rather spending 36 bucks on the cheap Copper Plugs and change them sooner then they should be, and experience some problems with their car mis fire or not run properly, and spend another 36 bucks for another set. Just Invest 66 or let say 80 bucks into the right spark plug, that's my opinion.

 

the copper plugs cost 1.39 a piece a total of 8.34 cents. and usually us force induced guys use them for detonation purposes not because we are being cheap. but in my opinion going from platinum to copper i didnt notice any significant difference at all besides changing them more often because of the copper.

 

Ok i was wrong about the price. Did I mention anything about Force Induction in my post? Is this guy who bought the NGK Iridium IX plugs SC or Turbo Charged, or spray ready? Humm You are not getting my point? And you don't have a dyno on a NA car, not a forced Induction. In your Situation you are better off with copper I totaly understand.
Thanks.

 

its all good, the problem is a lot of new guys see copper is better but dont read the fine print of why. i felt really funny spending 1.39 on plugs with thousands of dollars in mods but this is what works for some of us. but like you said if your n/a platinum would be my choice.

 

By the way , have you dyno your car yet? Looks realy nice, it should sound realy nice as well?

 

no not yet, just really got it up and running about a month ago so still working out the bugs.i did have two nice runs against a stage 2 and stage 4 neon turbos as a start, and it ran very well.

 

Cool Nice!

 

We could argue all day over the merits between Platinum and coppers, but we all agree to stick with NGK, but this doesn't solve his problem. Changing coils is a costly venture and changing to Plats and finding out it is his coils wastes the Iridiums, so I'd suggest putting in a set of NGK coppers (cheap!) and if problem goes away buy Plats later or stick with new coppers when the coppers are done, if the problem doesn't go away then the money saved on the Plats will contribute to the cost of a complete set of coils.

BTW before buying the coils.....have you cleaned your TB and IAC valve?

 

You could be right, but maybe iridium IX messed up his coils?? Or maybe not, BTW I don't think TB, IAC valve cause Miss Fire!!! They can cause Excessive Engine shake, or vibration, and bad gas mileage, and not responsive.....

 

True, TB and IAC don't cause miss fire but in his first thread it says:"Rough idle & slight miss" as we're not actually there to witness I'm just trying to help with what could be a combination of problems, besides these are easy and cheap fixes.