Spark Plug Install Instructions

Stick with NGKs. That is all.

And your build date should be either on the plate that's on your left front strut tower, or on the label attached to your driver door well. Open the door and look along the bottom or the right vertical (B pillar).

there iridiums some people run platinums for a colder plug. does anyone run coppers?

dont mean to get off topic or thread jack!!

I am considering doing the plug change myself on my 97 GT sedan...

I hate to be discouraging, but my previous Subaru was a 97 (an Outback wagon, but I imagine the engine config is the same), and changing the plugs on it was absolutely horrific. Every single extension I had (and some I purchased for this job), feeding the extensions into the plug holes with my fingers before being able to snap them together, etc. The problem is just that the plug holes are perfectly aligned with frame members, so there's literally only maybe 2" of clearance on some of the plugs.

I tell you this because I think much of the info here, about the difficulty of changing the plugs, may refer to other generations. I now have an '06 (naturally aspirated) and changing the plugs is WAY easier. (I have no idea what the '99-'04 generation is like). Maybe other owners of '96-'97 can chime in of they think I'm overstating - but, I'd rather eat a box of nails than change the plugs on a '97 again.

Also, since you're new to the forum, I'll tell you that it's been my experience that people here tend to understate the amount of time it takes to complete a task - either that or I'm just a pisspoor mechanic (which I'd tend to doubt, as I'm an engineer and have been working on my own car for almost 40 years). I don't think people are trying to mislead, I think they're just saying "well, that's how long it SHOULD have taken me, if I wasn't drinking a beer or arguing with my girlfriend, or didn't do this or that stupid thing"; but, all those things are facts of life. It's a normal effect, one I see in my engineering work all the time.

 

I have to decide whether mine is "TO 04/97", or "FROM 05/97". I know my VIN but I can't find any date info on the car tags so far. Any suggestions?

 

Stick with NGKs. That is all.

 

And your build date should be either on the plate that's on your left front strut tower, or on the label attached to your driver door well. Open the door and look along the bottom or the right vertical (B pillar).

Okay I'll re-investigate the plugs. As far as the wires go, I couldn't find a date reference on the tags you mentioned. I called the dealer, and evidently my 1997 GT was made in 8/96. I am guessing that there are not very many 1997 GTs made after 5/97.

 

I hate to be discouraging

That was a bit discouraging! The dealer originally quoted me $200 for wires and plugs and I said okay. Then they called back and said that was just for the plugs, the wires will bring the cost to $300 including another $50 for an additional half-our labor of labor so I declined. It seems to me that once you've changed the plugs all the labor is done. Perhaps now I'll re-consider, maybe I can talk them down to $250 or something.

I hate to be discouraging, but my previous Subaru was a 97 (an Outback wagon, but I imagine the engine config is the same), and changing the plugs on it was absolutely horrific. Every single extension I had (and some I purchased for this job), feeding the extensions into the plug holes with my fingers before being able to snap them together, etc. The problem is just that the plug holes are perfectly aligned with frame members, so there's literally only maybe 2" of clearance on some of the plugs.

 

I wonder if you can jack up the engine a few inches (like I did on my 2005 LGT as shown in post #595)?

 

Also, since you're new to the forum, I'll tell you that it's been my experience that people here tend to understate the amount of time it takes to complete a task - either that or I'm just a pisspoor mechanic (which I'd tend to doubt, as I'm an engineer and have been working on my own car for almost 40 years). I don't think people are trying to mislead, I think they're just saying "well, that's how long it SHOULD have taken me, if I wasn't drinking a beer or arguing with my girlfriend, or didn't do this or that stupid thing"; but, all those things are facts of life. It's a normal effect, one I see in my engineering work all the time.

I agree with you 100%.

^I'm also planning to do tackle this myself. I got '05 (naturally aspirated). I believe it's pretty much the same as '06. What kind of extension(s) did you use?

I be really surprised if the '05 was at all different. I can't remember what extensions exactly, but nothing crazy. I came from above, removing the battery and air handler box. Took me 42 min (just kidding).

That was a bit discouraging! The dealer originally quoted me $200 for wires and plugs and I said okay. Then they called back and said that was just for the plugs, the wires will bring the cost to $300 ...

I paid about $60-70 for a set of wires, the official NGK ones via mail-order, so $100 extra for installed wires doesn't seem too bad.

I wonder if you can jack up the engine a few inches (like I did on my 2005 LGT as shown in post #595)?

Not that you mention it, I read about that - after the last time I did my '97 before I got rid of it. Sounds like a good idea - moving the engine just an inch or two could make a huge difference, I think.

Just got back from the dealer, got 10% off the whole job, or $79 plus a couple of hours of labor gratis for an unrelated issue. Also had the injectors pressure-cleaned which is a 105K thing and the fuel filter replaced.

I'll have to check out that mileage thing; I am expecting an improvement just from finally replacing the original wires, much less the rest.

And now for only a marginally related story:

The other issue was the reason I went back after the last time a couple of months ago, when I had the struts replaced along with a four-wheel alignment; I have been having issues with the ABS system for years.

I replaced the relay once and that worked for a year or two but then it started working only intermittently and when it did work it did not work well. It got progressively worse to the point that I preferred to drive it with the ABS light on more than with the ABS functional.

So while they were messing with the struts I asked them to check out the sensor cables, and sure enough there was a bad one. I let them order it with a written estimate for installation with one hour labor plus the cost of the sensor cable.

Fast forward 60 days, and both the service writer and the mechanic that wrote that estimate no longer work there! The new guy finds that the place where the sensor cable meets the brake is completely corroded from well over a decade of heavy road salt, and it's going to take another couple of hours of dealer$hip labor to install the sensor.

But I had a written estimate from the previous mechanic

It cost me an hour to have the cables checked but that was unavoidable, and having that estimate in writing saved me two hours on the back end. And my biggest fear, that I would still have problems and end up pulling the relay and fuse anyways, went unrealized because the brakes now work great.

Sorry for the OT, I should probably find an ABS thread that must exist as I have been reading up on the various earlier systems and their associated frustrations over the years. But I am glad I stuck with it, at least until that damn ABS light comes back on (knock in wood)!

Anyways, a good exercise in winning for once at the dealer.

Replaced mine as part of 60K maintenance. Went from 19 miles per gallon (MPG) on the highway to 27 MPG..... YIKES! Shoulda replaced them 5K miles ago....

WOW, around a 35% increase in gas mileage. I wonder if anyone else has gotten a near 35% increase in gas mileage after their 60k maintenance...

a 35% increase in gas mileage.

Yeah, I was pretty surprised. Plugs probably took more abuse due to my stop-n-go, never above 30 mph, 3 mile commute.

Yeah, I was pretty surprised. Plugs probably took more abuse due to my stop-n-go, never above 30 mph, 3 mile commute.

Confirmed. I did replace my plugs at 60K, but the wires were original 1996. Replaced both this time (105k), and got a similar mileage bump as mcg_.

Highly recommended!

I did the spark plug swap on my 07 OBXT Thursday and I have several observations.

First off, the job took me 6 hours total. I used almost every length extension to get the job done and I got several busted knuckles in the process. It took me longer to do this than to install my coilovers. I ended up removing the battery and airbox and ultimately bending the plastic air tube on the drivers side back far enough to lodge it under some of the wiring harness. The tube is squarely in the way and while the front portion is fairly easy to detach the rear was unreachable for me. I have large hands so it was all the harder. It is doable of course but very very tedious. Thanks for all the hints on removing the coil packs posted up in this thread. Having owned both I can tell you this job is harder than on the 2.5L 2nd gen Legacy. The difference is the coilpacks. On the second gen you just have to pull the plug ends and then it gets tedious. This is tedious for both halfs.

Secondly, installed in my car were Denso Iridium SK20HR11s. The gap on them was clearly visually higher than the stock replacement NGK SILFR6As I put in. The NGKs are supposed to be .031". I measured one of the plug gaps on a Denso at .044" and just looked them up and they are supposed to be .043". The color on them was good but I was experiencing some stumbling under hard acceleration and wanted to do this job before I put the AP tune on it. Do you all think the higher plug gap could have caused the stumbling? It does appear to be gone now.

Lastly, why oh why didn't Subaru port the unibody frame rails so you could get to these through the wheel wells?

ss

im doing mine sun im at 57 k miles and im sure there beat , going from stock to stage 2 at 51k to 57k . on plugs that where in there from the factory, also going from a cobb ap to opensource.. im sure mine are fried .. also bought a coil pack and a injector cause im getting cyl 3 misfire once and a while , so figured plugs are toast , and id rather be prepared incase its a pack or injector so, i covered all my bases..

plugs i got where ILFR6B..... all they had in stock and there the same as the 6a so

Iridium plugs are not to be adjusted. If you feel they are out of spec, exchanged them where they were purchased.

Really ? I know you have to make sure to not touch the electrode AT ALL, but other than that, why wouldn't you be able to adjust them ?