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Discussion Starter · #1 ·
Hey all,
Any thoughts on what the stock plug life is for a stock MS3? I'm at 36k miles, cold starts are not all that smooth anymore. Wondering about plug life.......
 

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Discussion Starter · #2 ·
No one offering any real world suggestions as to how long we can expect the stock spark plugs to last?

IIRC, Mazda suggested 70k miles. I'd have to pull out the owners manual to firm that.
In contrast, Cobb recommends swapping plugs every 15k when running their software. Granted, they recommend a non stock plug that's one heat range cooler to deal with the additional boost levels but it's hard to believe that 3 psi extra drops plug life from 70k miles to 15k miles.

I'm not running Cobb software, I'm basically stock. However, I have my doubts about these OEM plugs going 70k before they need changed and was looking to hear from some of you that have similar or differing opinions.
 

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Discussion Starter · #3 ·
ITV 22s! That ought to generate a ton of traffic ....... :pokey:

I'm really suprised no one has anything to offer on this. How can oem plugs last 70k and the Denso "one step colder" only last 15k? The reality lies in between those #s, somewhere.
 

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Stock plugs are good quality Iridium. How old is your car and what condition is your battery in?

Most people over look the battery and the CCA Cold Cranking Amps that the battery puts out.

Denso plugs will last longer than doober over there saying it will get 15K. F-ing Joke.
You are not running 22lbs of boost hitting 350whp you will get a good 50K mi out of them.
 

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Umm my stockers were toast sorta early on. Found cracked insulators and one fell apart in my hands on replacement. I installed the ITV 22's awhile back, hmm probably 25k ago. Had a couple events recently that felt like plug blow out, which never returned after the miss fires. Coulda been something on the MAFS too, but checked that and it was clean. In any event I am gonna change em out next week. Curious to see how they look.
 

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Changed out my Denso ITV-22 plugs with about 25k on em today in a hilarious escapade. Short of it is that the ones I removed were about as perfect looking as I have ever seen a plug look. Even color and all the insulators appeared flawless. Oh and I found the missing plug socket rubber grommet from my prior change out. It was on plug number one. (Dammit why won't my socket go on, oh hey THERE it is! Pays to have a pen light in your tool kit) Too a photo of old and new together and will post it in the next day or so.
Sure looks like my car is running well. 52 k on it and it just looks new still.
 

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I have 40K on my 07 speed3 and just got my plugs replaced this morning by the dealer. The engine light came on and the code was P0300 (if my memory is good) and it meant misfire. 2 of my pluf were fouled. I know nothing about plugs but 2 of them smelled like fuel... Dealer didn't want to conver under warranty but I was able to convinve him to. 40K seems low for me to replace plugs, but it might be normal for this car. Anyway, the dealer agreed that it was not usual to change plugs after such low mileage. BTW, my speed3 is stock other than the COBB SRI.
 

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You got way more miles outta your oem's then I did. Mine literally fell apart when I removed them.
 

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45k here and got the same P0300 code. Dealer did not cover it and charged an astronomical fee to replace them. Had i known it would not be covered i would have done it myself, but surprise! Pay the $100 code read fee we're charging because it's not a warranty item or let us do it for...


Car runs much smoother now as a result of the new plugs.

Looks like autozone for my next check engine light encounter. Or maybe i should just go cobb accessPORT?
 

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[quote author=dbuenger link=topic=137886.msg3081993#msg3081993 date=1240600833]
45k here and got the same P0300 code. Dealer did not cover it and charged an astronomical fee to replace them. Had i known it would not be covered i would have done it myself, but surprise! Pay the $100 code read fee we're charging because it's not a warranty item or let us do it for...


Car runs much smoother now as a result of the new plugs.

Looks like autozone for my next check engine light encounter. Or maybe i should just go cobb accessPORT?
[/quote]

Yikes. Well it takes me about 30 minutes to R&R the MS3 plugs. 45-50 minutes if I give everything a once over while I am at it. With shipping my replacements were 50 bucks basically. So maybe 100 is not that bad a price. Just not convinced that the OEMs are very good plugs. Nor am I convinced that the dealer would be as thorough teching my car as I would.
 

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oh, $100 was the read fee they were going to charge if i didn't let them do it. It was $100 more for them to update the CPU and replace the plugs.

i was going on a trip the next day so i didn't really have a choice in the matter.


I'm in total agreement with you by the way, I don't have a lot of trust that the dealer will do as thorough a job fixing the car as i would. That, combined with the costs involved, are the two biggest reasons I've begun working on the car myself; time permitting of course.

I'll probably let these plugs run for a while and end up replacing them with the denso's eventually.
 

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I'm in total agreement with you by the way, I don't have a lot of trust that the dealer will do as thorough a job fixing the car as i would. That, combined with the costs involved, are the two biggest reasons I've begun working on the car myself; time permitting of course.

I'll probably let these plugs run for a while and end up replacing them with the denso's eventually.
« Last Edit: April 27, 2009, 09:17:51 AM by dbuenger »

Yes I think that a lot of us are on the same page. It may just be that working on our cars is just a PIA for them, but whatever. I have actually grown fond of working on mine.

Really happy to have found a plug that seems to work well and will last. Of course the 2010's are almost here. :0)
 
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