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View Full Version : Spark plugs--how/when to inspect and replace?



vtluu
01-19-2005, 07:13 PM
N00b-ish question: my car's coming up on 24k miles, and I've read a few stories of people with relatively low mileage and fouled-up spark plugs. So I'm wondering, typically how often do sparkplugs need to be replaced? What if I drive the car hard (lots of track and auto-x events)? Is the right answer simply for me to inspect them and decide? (And what do I look for?) And is there any advantage of getting aftermarket vs. OEM sparkplugs, cost or performance-wise? (I figure, a spark is a spark as long as it ignites the fuel.) Finally, how exactly does one "gap" a sparkplug?

EvoVIII
01-19-2005, 07:28 PM
Read the Sticker on top of ur Sparkplug cover!! don't get after market plugs it doesn't do anything and it will mess up ur Top end, thats what I have seen b4 on my dyno graph.. and after I retune my car, is fine now with OEM spark plug

evo_dadi
01-19-2005, 07:42 PM
umm its all different doug ;) hey tam autozone sells a cheap spark plug gapper for about a buck or so.ill take a pic of mine to show you or i can loan it to you since already changed my plugs.i have the old school type where you put a curved wire between the tip of the plug,thats for measuring.then the other side of it is to bend the arm either away or towards the tip of the plug.

afaik if the tip is black its rich then if its white its lean.i guess the ideal look would be like brownish.the copper plug has a better conductivity compared to the iridium but has a shorter life span.its not a huge difference but its a must for optimal performance :D

evo_dadi
01-19-2005, 07:47 PM
here's a cheap spark plug gapper
http://www.lislecorp.com/images/gappers/67800l.gif
rest of the link is here http://www.lislecorp.com/tool_detail.cfm?detail=1083

vtluu
01-19-2005, 07:48 PM
Read the Sticker on top of ur Sparkplug cover!!
I'm pretty sure the only thing it says on top of the sparkplug cover is "MITSUBISHI" :), or are we talking about different parts? (Or is there a sticker on the other side?)

evo_dadi
01-19-2005, 07:49 PM
lol there is a sticker on top that says only use oem plugs on mine :D

EvoVIII
01-19-2005, 07:59 PM
hey our Plugs is pregap already from the factory, but u can always double check it, btw did u change the Hotside of ur turbo urself Marcel?? how long did it take u?? any big gains out of it??

evo_dadi
01-19-2005, 08:08 PM
gruppe-s installed my hotside i would love to try it but i dont want break things up :lol: gains noticeable for sure nothing like a kick in the nut :P

vtluu
01-19-2005, 08:11 PM
MD374841 is the OEM sparkplug(s), $18.35 from MitsubishiParts.net. Anybody know if the part number is for a single plug or does it come as a set of 4?

EvoVIII
01-19-2005, 08:16 PM
MD374841 is the OEM sparkplug(s), $18.35 from MitsubishiParts.net. Anybody know if the part number is for a single plug or does it come as a set of 4?
I think they are single.. PM that guy in SoCalEvo.net, I just brought a set from him for $40 shipped, think his SN is jdmitr

How much did u pay for the Hotside installed at Gruppe-S? and how long did it take them to install it?

evo_dadi
01-19-2005, 08:31 PM
its per piece :shock: damn oem cost too much thats why i got the copper instead less than $10 for all four :wink:

hey doug give mike a call at the shop so he can give you a qoute.when they worked on mine they were changing the o2 hosing also and i stayed till later to dyno the car after :D so i would say about 3-5 housr including cool down since i had to drive far to go there.

vtluu
01-19-2005, 08:53 PM
Thanks for the tip, I found this thread on SoCalEvo.net useful: http://www.socalevo.net/forums/viewtopic.php?t=3153

Looked up the Evo on the NGK website; the NGK part # for the stock "laser iridium" plugs is IGR7A-G but I can't seem to find those for sale (other than from Mitsubishi of course). The NGK BPR7EIX plugs for $6.53 :shock: each here: http://www.rockauto.com/catalog/catalog.php?catalog=100&partnum=4055&a=FR100-4055

Not sure about the gap yet, it comes with 0.032 inches, but there seems some confusion as to what the stock gap is, 0.028" or 0.039". Maybe best bet will be just to measure the ones off the plugs I take out.

Said Jamie on EvoM: http://forums.evolutionm.net/showpost.php?p=1431369&postcount=8


OEM plugs should be OK until 60K. It's a good idea to take them out a time or two to help prevent them from seizing down the road. If you go with a copper plug, you'll want to change them more often (12K-24K).

EvolvedDSM
01-19-2005, 11:31 PM
I stand by the BGK BPR7ES copper plug gapped at .028" :) Sure you'll replace them more often, but it's something I already do. Besides, they cost 1/10 the price while lasting 1/5 as long... you do the math and tell me what the better deal is ;) I yanked my OEM plugs at about 7K and have been running the coppers since.

ace33joe
01-20-2005, 02:22 AM
I ordered a set of Denso Iridium plugs with stock heat range.

I had good experience with these at my previous car, so I would like to try them in my EVO too.

I read some article about the gap of the plugs, and it basically says "bigger gap is better, but requires higher voltage". Because rich fuel/air mixture is harder to ignite, usually turbo applications have smaller gap than NA ones.

But according to Denso, their 0.4mm iridium tip, and U-groove electrode design can reduce the voltage requirements, so the pre-gapped 0.044'' gap is supposed to be fine with stock engine. But they say we can gap it if we want.

I think I will try with 0.044'' gap with Ralliart spark plug wires. (They suppose to deliver more voltage to the plugs) If it's not working, I will re-gap them later. :)

Here is the article from Denso FAQ list.

Q. Do I need to set the gap?
A. Generally, no. The DENSO Iridium Power plug comes pre-set with a protective sleeve over the firing end, to protect the gap from accidental alteration. DENSO Iridium Power’s ultra-efficient firing power compensates for normally recommended gap settings that are smaller than the pre-set value. In the cases of vehicle modifications (nitrous, turbo-chargers, super-chargers, high power ignition systems, etc.), some adjustments may be desired. Or, if you prefer to remain consistent with factory specifications, you may adjust. However, please be careful not to place any stress on the fine center electrode during adjustment. You could accidentally break off the very hard, and therefore brittle, tip.

RonV
01-20-2005, 09:38 AM
I stand by the BGK BPR7ES copper plug gapped at .028" :) Sure you'll replace them more often, but it's something I already do. Besides, they cost 1/10 the price while lasting 1/5 as long... you do the math and tell me what the better deal is ;) I yanked my OEM plugs at about 7K and have been running the coppers since.

Yeah, and on a turbo motor, it's allot easier to blow the spark out with coper plugs. The iridiums are not just sort of gimmick to get your cash.

EvoVIII
01-20-2005, 12:27 PM
I ordered a set of Denso Iridium plugs with stock heat range.

I had good experience with these at my previous car, so I would like to try them in my EVO too.

I read some article about the gap of the plugs, and it basically says "bigger gap is better, but requires higher voltage". Because rich fuel/air mixture is harder to ignite, usually turbo applications have smaller gap than NA ones.

But according to Denso, their 0.4mm iridium tip, and U-groove electrode design can reduce the voltage requirements, so the pre-gapped 0.044'' gap is supposed to be fine with stock engine. But they say we can gap it if we want.

I think I will try with 0.044'' gap with Ralliart spark plug wires. (They suppose to deliver more voltage to the plugs) If it's not working, I will re-gap them later. :)

Here is the article from Denso FAQ list.

Q. Do I need to set the gap?
A. Generally, no. The DENSO Iridium Power plug comes pre-set with a protective sleeve over the firing end, to protect the gap from accidental alteration. DENSO Iridium Power’s ultra-efficient firing power compensates for normally recommended gap settings that are smaller than the pre-set value. In the cases of vehicle modifications (nitrous, turbo-chargers, super-chargers, high power ignition systems, etc.), some adjustments may be desired. Or, if you prefer to remain consistent with factory specifications, you may adjust. However, please be careful not to place any stress on the fine center electrode during adjustment. You could accidentally break off the very hard, and therefore brittle, tip.
I have a 1 step colder Denso plugs, u do not need to gap it :D you should have just ask me to give u my set!!

ace33joe
01-20-2005, 02:05 PM
I have a 1 step colder Denso plugs, u do not need to gap it :D you should have just ask me to give u my set!!

Hey, Doug. Didn't you have the Denso racing plugs? Mines are just regular Denso Iridium plugs with stock heat range. I appreciate your offer, though. :)

EvoVIII
01-20-2005, 05:29 PM
I have a 1 step colder Denso plugs, u do not need to gap it :D you should have just ask me to give u my set!!

Hey, Doug. Didn't you have the Denso racing plugs? Mines are just regular Denso Iridium plugs with stock heat range. I appreciate your offer, though. :)
those are NGK racing plugs which I sold it already

EvolvedDSM
01-21-2005, 11:29 PM
I stand by the BGK BPR7ES copper plug gapped at .028" :) Sure you'll replace them more often, but it's something I already do. Besides, they cost 1/10 the price while lasting 1/5 as long... you do the math and tell me what the better deal is ;) I yanked my OEM plugs at about 7K and have been running the coppers since.

Yeah, and on a turbo motor, it's allot easier to blow the spark out with coper plugs. The iridiums are not just sort of gimmick to get your cash.

NGK copper=good enough for 30PSI=good enough for me :)

vtluu
01-29-2005, 11:41 PM
Okay, so the factory manual says the gap should be 0.7-0.8mm, so 0.8mm or 0.0315 inches on the high side. The NGK plugs I got come gapped at 0.032 inches, so they're 0.0005 inches or 0.013 mm (or 13 microns) above spec. That's roughly half the width of a human hair. Should I bother re-gapping it?

EVO GRIM
01-30-2005, 09:26 AM
I think that should be fine. Those gap gauges are only so accurate anyhow.

Eclipse
01-30-2005, 10:50 AM
I stand by the BGK BPR7ES copper plug gapped at .028" :) Sure you'll replace them more often, but it's something I already do. Besides, they cost 1/10 the price while lasting 1/5 as long... you do the math and tell me what the better deal is ;) I yanked my OEM plugs at about 7K and have been running the coppers since.

So DSM plugs work? Same idea with the heat ranges and gaps as DSMs?

Scott

EDIT: FWIW you're not supposed to gap either iridium or platinum plugs because it can damage the electrode. And in the case of platinum it easily breaks the larger insulator.

carbonevo8
01-30-2005, 12:42 PM
hey guys i got a good one for you. a few months ago i decided to check my plugs. well this is the first time they have ever been removed from the car and sure enough one of the plugs was jacked it looked like when mitsu put the car together that they dropped one of my plugs because the top part of the plug was almost tuching the diode. i mean you couldnt get a gap tool in there if you tried. so i replaced them and man the car ran so much better. well the stock plug is NGK BPR7EIX and i went with NGK BPR8EIX because i needed one step colder because the oem plugs were white on top from over heating. i strongly suggest that you go with oem or NGK BPR7EIX (same plug) and stay away from denso. i noticed that denso plugs are shorter than the ngk so that means that they dont get in the center of the cylinder as well. allso you only need to go one step colder if you have lots of mods and are running more boost. oh yeah when gapping a iradium plug be careful they will break easily. ngk's website shows you how to do it the right way

vtluu
01-30-2005, 01:13 PM
The OEM plugs are the NGK IGR7A-G "Laser Iridium". The ones I got are the BPR7EIX "Iridium IX" which is their top-of-the-line iridium plug. Paid $6.22 ($7.55 shipped) a plug for the set of 4 from the following link: http://www.rockauto.com/catalog/catalog.php?catalog=100&partnum=4055&a=FR100-4055

EvolvedDSM
02-19-2005, 09:51 AM
I stand by the BGK BPR7ES copper plug gapped at .028" :) Sure you'll replace them more often, but it's something I already do. Besides, they cost 1/10 the price while lasting 1/5 as long... you do the math and tell me what the better deal is ;) I yanked my OEM plugs at about 7K and have been running the coppers since.

So DSM plugs work? Same idea with the heat ranges and gaps as DSMs?

Scott

EDIT: FWIW you're not supposed to gap either iridium or platinum plugs because it can damage the electrode. And in the case of platinum it easily breaks the larger insulator.

For the most part, yes. The EVO heat range is one step colder to start with vs. a DSM.

missred
10-18-2005, 07:03 PM
The OEM plugs are the NGK IGR7A-G "Laser Iridium". The ones I got are the BPR7EIX "Iridium IX" which is their top-of-the-line iridium plug. Paid $6.22 ($7.55 shipped) a plug for the set of 4 from the following link: http://www.rockauto.com/catalog/catalog.php?catalog=100&partnum=4055&a=FR100-4055

I think its time for a change, so how did these plugs work for you? :D

methods4
10-18-2005, 10:06 PM
Yeah, and on a turbo motor, it's allot easier to blow the spark out with coper plugs. The iridiums are not just sort of gimmick to get your cash.

FWIW, I only ran NGK BPR7ES on all my DSMs. $8 for a set of plugs can't be beat. I had no blow out or spark issues at 25psi of boost running 400whp.

So I would say depending on car, the Iridiums are unecessary. Earlyapex runs copper plugs in his MR and continues to rape everyone on track. YMMV.

missred
10-18-2005, 10:42 PM
Yeah, and on a turbo motor, it's allot easier to blow the spark out with coper plugs. The iridiums are not just sort of gimmick to get your cash.

FWIW, I only ran NGK BPR7ES on all my DSMs. $8 for a set of plugs can't be beat. I had no blow out or spark issues at 25psi of boost running 400whp.

So I would say depending on car, the Iridiums are unecessary. Earlyapex runs copper plugs in his MR and continues to rape everyone on track. YMMV.

Thanks for the info man, as far as gapping on the plug goes in the range of .028-.032 be okay?

bdking57
10-22-2005, 09:39 AM
I changed mine out about 6 months ago... the ones I had in there were pretty nasty. With the evo you can almost feel when they need to be replaced.. you kinda of start feeling alot of hesitating and noticable blurps at part throttle. Also I think i read somewhere that the plug wires should be replaced every 60K miles.. I just ordered ralliart spark plug wires and I may try my luck with cooper plugs. If using the NGK iridiums in one step colder right now.. going with the colder plug give less chance of detonating, but at the cost of crappier idle

akandari
10-14-2006, 05:07 PM
Here is a good link to check the condition of ur spark plugs and give an idea of whats going on in ur engine;

http://www.machv.com/diagsparplug.html

DaveLC2
10-14-2006, 06:32 PM
I also run the NGK's and have had no problems. The oem's were showing signs of wear at about 20k miles. I just change them out every 5-7k miles and they work just fine. I am about to turn 48k miles now. I think I want to decarbon my engine to make sure everything is cool.

Dave

rigd1
11-01-2006, 12:54 PM
Does anyone know what spark the ngk part # is for some Evo IX plugs? I heard they are different than the VIII and I can't find any info about it. I want to change the stock ones out for a colder plug soon.

Any info on this would be appreciated.

Jamie@WORKS
11-01-2006, 01:56 PM
NGK ILFR7H is the stock IX plug.

vtluu
11-01-2006, 02:13 PM
Heheheh, I was wondering, "Who's the n00b who started this thread?" :lol:

I now use NGK BPR7ES plugs like Bryan and Tony; I replace them every oil change (3-4 track days). Gap them to 0.026-0.027" (they come gapped to 0.032").

$1.70 each (in packs of 10; I buy 20 at a time) at RockAuto.com (which also has the best prices I've seen on the NGK iridiums): http://www.rockauto.com/catalog/x,carcode,1421446,parttype,7212

missred
05-02-2007, 08:41 PM
Found a pretty good price on some NGK BR7ES plugs at Pepboys for $1.89 each.

lncrevoviii
05-02-2007, 09:24 PM
Found a pretty good price on some NGK BR7ES plugs at Pepboys for $1.89 each.


wow pretty damn good price. But wait there is NGK BPR7ES and Paul you said BR7ES, is there a difference or you mispelled.

I might need new plugs soon. I was also searching for some feedback. Anyone know how easy is to replace them by urself? Do I need the sparkplug tool?

missred
05-02-2007, 09:29 PM
Found a pretty good price on some NGK BR7ES plugs at Pepboys for $1.89 each.


wow pretty damn good price. But wait there is NGK BPR7ES and Paul you said BR7ES, is there a difference or you mispelled.

I might need new plugs soon. I was also searching for some feedback. Anyone know how easy is to replace them by urself? Do I need the sparkplug tool?


D it really is BR7ES, felt no difference except for the fact that I change my plugs every 2 or 3 oil changes lol

earlyapex aka jack ass
05-02-2007, 09:36 PM
BPR7ES is protruding tip while BR7ES is not. Non protruding are said to run 1/2 step colder

MadEvo
05-02-2007, 09:40 PM
BPR7ES is protruding tip while BR7ES is not. Non protruding are said to run 1/2 step colder


Bryan, what do you recommend using for a modified Evo/daily driven?

XVeloX
05-02-2007, 09:52 PM
Considering how cheap the BPR7ES are from www.rockauto.com when bought as a pack of 10 i run them on my DD. No problems. And to the guys above installing and gapping has to be the easiest self service you can do on these cars hehe

lncrevoviii
05-02-2007, 10:01 PM
So when you guys say you actually change your plugs every oil change or 2, is it because its necessary or just for optimized performance of the vehicle and safety precautions. I am pretty sure its for optimized performance of the vehicle.
Most of you guys changing your plugs every oil change or so are doing Auto X or Track, basically your engine goes through a hell of a beating in one track day than a daily driven car.


Well, what I am getting at is I am at about 18K, should I? I don't Auto X nor Track. So, would BPR7ES be good or I should just stick with BR7ES

But what about having injectors? Since more fuel is being dumped, doesn't it require better spark, please do correct me if I am wrong.

earlyapex aka jack ass
05-02-2007, 10:05 PM
BPR7ES is protruding tip while BR7ES is not. Non protruding are said to run 1/2 step colder


Bryan, what do you recommend using for a modified Evo/daily driven?


Stock iridiums or the BPR7ES/BR7ES will work fine.

XVeloX
05-02-2007, 10:23 PM
So when you guys say you actually change your plugs every oil change or 2, is it because its necessary or just for optimized performance of the vehicle and safety precautions. I am pretty sure its for optimized performance of the vehicle.
Most of you guys changing your plugs every oil change or so are doing Auto X or Track, basically your engine goes through a hell of a beating in one track day than a daily driven car.


Well, what I am getting at is I am at about 18K, should I? I don't Auto X nor Track. So, would BPR7ES be good or I should just stick with BR7ES

But what about having injectors? Since more fuel is being dumped, doesn't it require better spark, please do correct me if I am wrong.


i guess the simple answer is that the stock plugs are iridiums (as mentioned above) which last a lot longer than the BPR7ES. The BPR7ES are a hellov a lot cheaper though and arguably perform better because they are 1 step colder. With only 18k you are probably fine. Shoot i think the service manual says to replace at 60k. I replace mine every 6k-10k just for drivability. And at $6.80 for 4 plugs i'm not too worried about the cost

lncrevoviii
05-02-2007, 11:32 PM
So when you guys say you actually change your plugs every oil change or 2, is it because its necessary or just for optimized performance of the vehicle and safety precautions. I am pretty sure its for optimized performance of the vehicle.
Most of you guys changing your plugs every oil change or so are doing Auto X or Track, basically your engine goes through a hell of a beating in one track day than a daily driven car.


Well, what I am getting at is I am at about 18K, should I? I don't Auto X nor Track. So, would BPR7ES be good or I should just stick with BR7ES

But what about having injectors? Since more fuel is being dumped, doesn't it require better spark, please do correct me if I am wrong.


i guess the simple answer is that the stock plugs are iridiums (as mentioned above) which last a lot longer than the BPR7ES. The BPR7ES are a hellov a lot cheaper though and arguably perform better because they are 1 step colder. With only 18k you are probably fine. Shoot i think the service manual says to replace at 60k. I replace mine every 6k-10k just for drivability. And at $6.80 for 4 plugs i'm not too worried about the cost



I might still do that at my next oil change at 20k. I mean considering the cost, just like you said couple of posts up :D.

MarkSAE
05-03-2007, 04:05 AM
The stock plugs will last. I didn't change mine til 30k and they were still good when I pulled them. And I did a ton of track days on them. I replaced mine w/ another set of stock iridiums cuz they last long and I like taking the lazy approach. ;)

evo_dadi
05-03-2007, 06:54 AM
bah!! cmon now mark ya lazy bum :lol: :P

MarkSAE
05-03-2007, 07:58 AM
The iridiums seem to have about 5-6X the life of the copper plugs, so paying 5-6X more for each plug is worth it to me. It all costs around the same in the end, but I save time on labor w/ the iridiums. ;)

missred
05-04-2007, 01:34 PM
I was also able to find some BPR7ES at Vic Hubbards in Hayward, I bought a box for like $12.68

XVeloX
05-04-2007, 01:36 PM
for 10 spark plugs?!?!

missred
05-04-2007, 01:38 PM
for 10 spark plugs?!?!


8 plugs to be exact.

XVeloX
05-04-2007, 01:41 PM
nice! that's 1.585 per plug. At Rockauto you get a 5% discount emailed to you occasionally which knocks the box of 10 down to 1.615 per plug, plus shipping...nice find!

lncrevoviii
05-04-2007, 08:55 PM
I was also able to find some BPR7ES at Vic Hubbards in Hayward, I bought a box for like $12.68


Vic Hubbard FTW!!

definately nice find. :)