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Spark Plugs Revisited


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35 replies to this topic

#1 PAezb

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Posted 18 December 2003 - 09:10 PM

OK, OK. I know spark plugs have been discussed to death here, but I need a warm and fuzzy from any of you on a purchase of NGK V-Power plugs that I plan to install in my 96 OBW/2.5/auto/130K.

I originally went into the local auto parts store to inquire the price on the NGK Iridiums plugs - $21 a piece - yikes!!! The counter guy shakes his head and said he could order the iridiums for me, but sold me on a set of V-Power NGK at under $2 a piece.

I was originally thinking the Iridiums just for the fact that I didn't want to replace the plugs again for the remaining life ,or ownership, of the car.

At $2 a piece I'm wondering how good these plugs are.

Comments?

Paul

#2 99obw

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Posted 18 December 2003 - 09:47 PM

I use the laser platinums at 60k intervals. Generally you get what you pay for. You won't get nearly that many miles out of a non-platinum plug before fuel economy and engine starting begin to suffer. You can get a better price on the internet for the iridiums. IIRC someone said that one of the parts stores has really good prices on the NGK platinums, something like $10 each. You might find it using the search feature.

#3 GLCraig

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Posted 19 December 2003 - 01:54 AM

The NGK V-Power plugs are the OEM plug in most markets. Some US built models got champions instead but the dealerships install NGKs when doing a tune up.

#4 Setright

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Posted 19 December 2003 - 01:55 AM

I like to replace plugs for approximately every 20k miles. I have been through most of the repertoire, expect Iridium - too expensive. I find that Bosch "Super Plus Yhtrium" work very well, and show little sign of breakdown when I pull them for replacement. NGK's show noticable wear on the electrode at this mileage.

I do like the fact that I have look into the combustion chamber every 20k miles, gives a good indication of how the engine is doing. Leaving Iridium plugs in there forever, would mean I miss out in this. Please, don't tell me that I can pull them occasionally, because I don't like to install used gaskets, and where on earth would I find replacement gaskets for these plugs?

#5 DerFahrer

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Posted 19 December 2003 - 03:22 AM

NGK V-powers are the best plugs you can put in your car. Period. I will stand by this until the day I die. The only problem with them is they don't last around the corner... But I personally think you should pull the plugs out to check your engine's condition more often than 60k anyway!

#6 NOMAD327

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Posted 19 December 2003 - 06:55 AM

After you have changed a set of spark plugs on a DOHC outback, you will wish they weren't due to be changed again for another 60,000 miles

#7 99obw

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Posted 19 December 2003 - 07:13 AM

Agreed!

I think the laser platinums are the OEM plug on the Phase I 2.5, at least for '99.

Here is the other thread I was thinking of.

#8 PAezb

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Posted 19 December 2003 - 09:08 AM

Thanks for all your replies. The plugs that I have in there now, (I know most of you will be rolling your eyes...:rolleyes: ), are Bosch Platinums +4s. I've got 70K on these and I have to say I have been very happy with them - they were about $5 a piece if I remember correctly. The idle and acceleration is still good. I've had no misfires, and no CELs, that I was told by the dealer might happen when they were installed. I may wait a just a bit longer to pull them but I figure they'll need to be replaced soon.

I was considering the Iridiums due to the comments of others here on what a PITA it is to change the plugs, and to go with longer life plugs. Is the 120K ratings on Iridiums realistic? The Bosch plugs were put in around 62K by the dealer (also had oil leaks so the seals were done then also). But given the high prices the dealer charges I have been doing most of the maintenance myself ever since, so I know my way around the engine bay pretty well - maybe it won't be that bad. I may still throw the V-Powers in there just to see if I notice any "performance improvement".

I guess I better check the resistance of the wires too - they are still the originals. Anyone know what the values should be?

Paul

#9 99obw

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Posted 19 December 2003 - 09:11 AM

Not to spend your money for you, but at that mileage I would just replace them.

If nobody chimes in I can look up the resistance in the FSM when I get home.

#10 PAezb

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Posted 19 December 2003 - 09:26 AM

Thanks, I'd appreciate that. Yeah I might as well replace them, but I'm curious on how the currect wire values are holding up after 130K.


BTW, I've had to throw a little money and work into this car this past year - failing sensors, timing belt, tire, fluid changes, etc. All normal expenses I expect. With the replacement of plugs and wires, this should be it for a while. The only worry, would be to have the original head gaskets go which we all know these phase I engines are notorious for, on TOP of the work and money invested so far. So I'd apprciated a little Subie prayer for my OBW...(attempted humor here...:-p )

I still like the car...

Paul

#11 Warp3

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Posted 19 December 2003 - 09:36 AM

I use nothing but the NGK V-powers in my 2.5RS...it's the stock plug (well my car actually came with Champions (as did most, if not all, 2.5RS models) but most Subarus come stock with the NGKs and Subaru uses NGK for replacement plugs). (From what I've read, the reason for Subaru using Champions at all is some weird x% of U.S. content on imported cars law.)

Besides, the Subaru World Rally Team runs NGK...:D

#12 99obw

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Posted 19 December 2003 - 07:55 PM

From the FSM:

Resistance value:

#1 and #3
6.43 — 15.01 kohms

#2 and #4
6.67 — 15.57 kohms

#13 forester2002s

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Posted 19 December 2003 - 08:41 PM

The electrical resistance of spark-plug leads doesn't always tell you the whole story, in my experience.

A lead may be faulty at high-voltage (causing misfire), but show a 'normal' resistance value at the low-voltage applied by a multi-meter.

However if the resistance measures too high, then the lead should be replaced.

While we are on the subject of spark-plug leads, what make do people use on their Subies?

#14 99obw

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Posted 19 December 2003 - 08:48 PM

I agree, testing a high-tension wire with a low voltage will only tell part of the story. I don't test spark plug wires, instead I replace them every 120k miles, or every other plug change in my case.

I use only OEM parts.

#15 sprintman

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Posted 21 December 2003 - 12:49 AM

I have NGK Iridiums in my 00 OB and really impressed. Use them in a Mazda turbo as well and as good as when they were installed. If there are better plugs than these then I want to know about it?

#16 northguy

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Posted 21 December 2003 - 09:35 AM

$2, $5, $10, $21. x 4 cylinders = a maximum of $84 over 60,000 miles - still cheap considering you're not doing any kind of tune-up in between. But the clincher is that you're looking at messing with the performance of a $20,00 + vehicle. I'd just put in oem specs and not quibble. But hey, that's part of the reason I drive an 83 Brat - I'm miserly (cheap). If I destroy the engine in it, I've already got a replacement sitting under the front steps of the house.

#17 blitz

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Posted 21 December 2003 - 10:03 PM

I've run the Denso U-Groove's in a previous vehicle (Mitsubishi) for 176k miles (a fresh set every 20k miles) with excellent results and subsequently tried 'em in my '02 OBS with equally good results. These are about equivalent to the NGK "V-Groove" coppers I'd guess.

Anyway, in my efforts to try to crispen the soggy throttle response, I swapped in some Denso Iridiums. Now while I'm not sure that I noticed any real improvement in the way the car ran, I did pull em' out after about 8k miles just to have a look-see, and I noticed that a couple of the plugs appeared as though the long, needle-thin (.4mm) center electrode turned to a ball of molten iridium at the very tip. Mind you, the plugs themselves (ceramic insulator, ground electrode, etc.) showed no indication of heat-range abnormalities, only the very tip of the center electrode. It's my belief that there is a limit to how long and thin the center electrode can be made before heat cannot escape and a "plasma" condition occurs.

I got me a set of NGK IridiumIX to swap-in next. These have a slightly thicker (.6mm) and measurably shorter center electrode, which ought to sink heat more effectively. Also, they were a heck of a lot cheaper.

#18 99obw

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Posted 22 December 2003 - 03:55 PM

The NGK laser platinums hold up really well. Right now I am looking at one of my 60k mile old PFR5B-11 plugs. It looks just like the day I put it in, except darkened a bit too much from a bad O2 sensor.

I am a little too cheap to try the iridiums.

#19 nickb21

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Posted 22 December 2003 - 06:57 PM

Glad I read through this thread, I'm coming up to my 30k mark and am due for a plug change ('02 OBW). From what I've read I'll be going with the NGK's, even though the factory plugs are champion I believe. Not sure if you guys have a napa around, but I just looked up their proces online:

NGK - Iridium IX
3764 $ 8.49

NGK - Laser Plat.
4014 $ 12.69

NGK - G Power Plat.
7092 $ 2.19

I thought the iridum's were better plugs, wonder why they would be cheaper...

#20 Warp3

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Posted 23 December 2003 - 12:02 AM

From what I've read I'll be going with the NGK's, even though the factory plugs are champion I believe.


Like I mentioned in my post above, some Subarus do come with Champions originally but I've never heard of Subaru dealers using anything but NGK for replacement plugs (and the part numbers for both brands are listed in the owners manuals regardless of which plug they originally came with).

#21 DerFahrer

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Posted 23 December 2003 - 01:34 AM

No matter what anyone says, if you want the BEST performance from a spark plug, look no further than NGK V-powers. Period. Copper is the best conductor of electricity that us humans know about, that is simple chemistry. Anyone that says a different type of plug performs better simply has not tuned their butt dyno right :-)...

The only exception to this is when a car calls for plats or irids as per the manufacturer. Certain characteristics of the engine are designed for those plugs, and therefore that's what will run best. Copper is still a better conductor, but the engine was not designed to appreciate that :brolleye:

As for other brands, here's a simple rule to follow: The origin of the plug should correspond to the origin of the car (read: Japanese cars run best with Japanese plugs, American with American, etc. etc.) Bosch plugs run GREAT in BMW's and Merc's, but not in Subarus. I have never heard truly positive reactions from people with Bosch plugs in their Scoobs. I myself had no increase in performance, only worse gas mileage.

I understand that the "middle-of-the-head" spark plug location of EJ25's does not make the job any easier (EJ22's are on the upper side of the head, much easier :D), but I would still remove the plugs more often than 60k to 100k to at least check their condition.

#22 99obw

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Posted 23 December 2003 - 12:14 PM

Originally posted by subyluvr2212
Copper is the best conductor of electricity that us humans know about, that is simple chemistry.



Not exactly. Of the common conductors silver is the most conductive by a small margin over copper.

I have heard only complaints about Bosch platinums myself. I personally have had excellent luck with Autolite platinums in other makes. I feel a bit guilty putting Champion plugs in my lawn mower, I can't imagine putting them in a Subaru.

#23 bratman2

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Posted 23 December 2003 - 06:51 PM

I also used Bosch plats in my Brat once, for about two weeks until I installed the old NGK v powers that I had failed to throw away yet. This was the only way to solve a miss at steady cruising that happened the same day the bosch plugs were installed. Glenn Taylor.

#24 Commuter

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Posted 23 December 2003 - 10:00 PM

I too have read of several Subaru owners that tried the Bosch plugs (+4's most notably) and they just didn't "work well" in the engine. Some seem to have luck with them, but most don't.

Some time ago, I read that the 4 ground plugs end up blocking the development of the flame front. That does make some sense to me.

A couple of years ago, I decided to try the TorqueMaster plugs. The web site is rather thin. The place seems to be pretty much a "ma and pa" operation. But the technology is interesting, even patented.

It's a pretty conventional plug, but with a wide gap and a full surround ground. Note that the ground is to the "side" of the center plug, not on axis. You can read about it, but in brief, the spark comes off the 'side' of the center electrode, across a plasma field on the surface of the ceramic and then jumps to the ground. Once a spark forms, the resistance increases, which causes the spark to 'move', hence spinning and creating a sheet, or disk of spark exposed to the air-gas mixture. (This "increasing resistance, spark moving" aspect is the reason for V grooves and multiple ground plugs as well. The spark initiates in one spot, then reforms in another. You get mulitiple sparks for every 'single' spark.)

Whatever. If you want to debate the technology, take it up with the inventor. What led me to this plug is that it is (was?) the only plug mentioned by name on Magnecor's web site. I got curious.

Mine have been in for almost 100k km now. And they were in briefly before that for about 30k km. (Things got interrupted by my engine change.) I can't say I noticed any major difference. Perhaps a tiny bit better "zip". They certainly haven't caused any misses or that as the mechanic was concerned about when he saw the wide gap. My decision to try the plugs related more the nature of the Phase I DOHC engine to build up carbon. I thought this plug might help the situation. I don't know if it has, but it certainly hasn't hurt. And they are suppose to last a long long time. Up to 200k miles. Eventually, the center electrode will wear down to the ceramic. And no exotic materials either. Just stainless steel.

So there you have it. Another twist on the venerable "spark plug". ;)

Commuter

#25 Tiny Clark

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Posted 24 December 2003 - 01:50 AM

I make my own out of old wire coat hangers and wine corks. Seems to work just as good as the others I've used...:drunk:

Merry Christmas everybody!

I hope you get everything you want & want everything you get.

Tiny




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