Spark Plug Install Instructions

So I put the old plug back in, and my car has been running a little strange since. My voltage used to be around 14.3V but is now about 13.9V, and my gas mileage is down about 10-20%. Intake temps used to be about 3 degrees (F) higher than ambient, but they're now about 20 (F) higher. Additionally it just feels a little sluggish and sometimes stutters before taking off.

Along with the plug, I also oiled my K&N filter-- maybe a little too much. I'm guessing my symptoms are from the plug and not oil that could be on the MAF.

Any thoughts on this?

So I put the old plug back in, and my car has been running a little strange since. My voltage used to be around 14.3V but is now about 13.9V, and my gas mileage is down about 10-20%. Intake temps used to be about 3 degrees (F) higher than ambient, but they're now about 20 (F) higher. Additionally it just feels a little sluggish and sometimes stutters before taking off.

 

Along with the plug, I also oiled my K&N filter-- maybe a little too much. I'm guessing my symptoms are from the plug and not oil that could be on the MAF.

 

Any thoughts on this?

I don't think the battery voltage has to do anything with it. As far as the gas mileage/performance. Somehow I feel that it's related to too much oil on the k&n filter since the MAF impacts A/F ratio and is very sensitive.

i'm sorry if this may have been discussed before... but for almost every site(including rockauto) has the LFR6AIX {#LFR6AIX11} Iridium IX; 0.43 Gap .030

a quick search for the ngk LFR7AIX shows it available on amazon. which do I go with?I just wanted to make sure that there are the same? maybe the part number has been updated?

I did the spark plugs on my car yesterday along with a friend. It took us over 3 hours to do mainly due to the two rear-most plugs.

I have a feeling most of my prior issues were due to not tightening the plug down enough. When I went to take that one out, it was extremely loose.

Everything has been changed over to NGK Iridium IX plugs and the car idles like a dream now.

And don't forget to reattach your front O2 sensor wire stand-off mount to the number 4 coil pack bolt. Was replacing my O2 sensor this past weekend and found that I didn't reattach the mount so it was just dangling there. It didn't help that I was replacing the plugs in a torrential downpour, so was going as quickly as I was, but it's easy to miss the O2 sensor mount. Just saying...

This. It's easy to miss but it takes just a few seconds to line up and secure it

Are the center electrodes made with ground down unicorn horns?

Geez.

The OEM plugs for my 05 ADM 2.0L twinscroll are NGK ILFR6B's.... just bought 4 at $38 each... ouch.

Doesn't Amazon have those for $10.xx each?

I just replaced my plugs, which were 10K miles overdue (for the 30K interval, they are the "laser platinum" NGK OEM plug). Then went on a roadtrip. I swear my mileage was 2-3 mpg better than I'd been getting. Seems surprising.

My mileage jumped up for the first few subsequent fillups. Then it went back to normal. Although the mileage jump also came with 0% ethanol gas + fresh plugs.

YMMV

Straight 93 versus E10 93 = +3-5mpg for me with the straight 93. And I can feel it while driving too. There's a reason the E10 is cheaer.

Did see 29.1mpg in mountainous terrain on this current road trip. That is post spark plug install, post O2 sensor install and driving at steady-state 72mph (boost threshold) average. Suspect that it could have been higher if not for the horribly hot (100+F) temps.

Are the center electrodes made with ground down unicorn horns?

 

Geez.

Yea.. but I called around and that was the going price for them here in oz. I'm also seeing a lot of people talking about 28-29 mpg but im lucky to get 20 mpg (12L/100Kms)... My 2.0L ADM liberty has forged pistons and runs 15psi from the factory though... I also have a heavy foot and mostly drive city. Anyone else only see about 20mpg around town? We use 98RON fuel for our 2.0 turbos here too. ouch again! >.<

Doesn't Amazon have those for $10.xx each?

Well.. they do.. but they're for used plugs...lol and they stock about 6 new plugs for slighty more... I'm not inclined to trust those in my baby.. Would rather go to a reputable auto store and get them shiney and new in a box, properly gapped etc.. If several suppliers say they're $35-40 each... I'm inclined to accept that. They're only changed every 100,000kms too.

Well.. they do.. but they're for used plugs...lol and they stock about 6 new plugs for slighty more... I'm not inclined to trust those in my baby.. Would rather go to a reputable auto store and get them shiney and new in a box, properly gapped etc..

Amazon isn't reputable ? I bought plugs from them (and brake pads and plug wires) and they were all shiny and new and in a box.

Straight 93 versus E10 93 = +3-5mpg for me with the straight 93. And I can feel it while driving too. There's a reason the E10 is cheaer.

Hmm, right after I changed my plugs, I went on a roadtrip from home in NC down thru SC, GA, and FL. Maybe they have different gas in those states, due to laws regarding ethanol usage ?

The only straight 93 you can find in SoCar (at least on the coast) is at those stations that cater to the boaters due to all of the fuel line/fuel-delivery issues attributable to using E10 in their boats.

And you can't get straight 87 or 88, there, only 93 which is always ~$.10-.12 more per gallon than E10 93. Better mileage, and performance, but at a price premium, literally

has anyone used the pulstar plugs? are they good or bad?

Did you end up using these? I am curious how they worked out. My LGT has about 57k on it so im thinking of changing out the plugs soon.

Most on here would recommend OEM spec plugs (NGK SILF6RA). They're a quality plug that's gapped correctly for our boosted engine and they'll last 60k+.

I got mine from Mike at Infamous.

http://www.infamousperformance.net/servlet/the-659/Subaru-NGK-Iridium-Spark/Detail

Most on here would recommend OEM spec plugs (NGK SILF6RA). They're a quality plug that's gapped correctly for our boosted engine and they'll last 60k+.

 

I got mine from Mike at Infamous.

http://www.infamousperformance.net/servlet/the-659/Subaru-NGK-Iridium-Spark/Detail

I went with the OEM plugs. They are such a pain to change that it wasn't worth it to me, for whatever savings might have been realized, to chance having them not work as well or to need to change them before another 60,000 miles.

Replaced mine today thanks to this walkthrough. I never found any particular part difficult, it was just time consuming in general. Took me probably 2.5 hours but it's not like I was in a rush.

I bought this spark plug socket which made getting the plugs out pretty easy, even the driver's side rear.

As far as putting the plugs back in, I did have to get them started with a normal spark plug socket and a drill bit adapter.

Leeloo Dallas Multiquote for printing...

I just did mine....

 

 

my two cents worth of tips:

 

the passenger side was a breeze after the airbox was removed, so I won't comment on that.

 

but for the driver side, the thick wire harness from the fuse box near the battery can be unclipped from the C-clip that holds it above the front coil pack. then you can push it toward the motor and tuck it under the eng cover for more access (especially to the rear pack/plug)

 

 

on the driver rear pack, unclip the driver front coil pack wire harness and tuck it away towards the firewall (rear of the engine). then, once you have the rear coil pack bolt loosened all the way, rotate the coil pack 180 degrees. the wire harness plug should be now easily removable. Also, with the pack rotated like that, it wiggles out completely from the top with no issues. just be sure to put it back in the same way you take it out. I was also able to do mine without removing the battery. and the tools listed are def necessary.

Good write up.

 

For installing the plugs, I've found that you can create your own flex extension by using a rubber hose that fits over the end of the spark plug. I use this to thread and seat the spark plug gently. Works surprisingly well.

A few tips:

- When replacing the rear plugs, getting the coils out of the way may seem impossible, unless you unplug it from the wire harness and turn it upside down 180deg then try removing it.

 

- When removing the nut on the passenger-side rear coil, you have to use an offset wrench, low-profile ratchet/socket or 12mm univ-socket. The space is tight back there.

 

- When unscrewing the plugs, some may take much more effort than you think is needed. When I did mine, 3 of them I could finish unscrewing with my hands but 1 was tight until the last thread that I thought it was cross-threaded, but it does not look like it is. I was able to screw it back in with no problem but still took way more effort, more than the 15ftlbs of torque, than I felt comfortable. Since my dealer was the only one that touched the plugs before I started doing my own. I took to them and they stated that sometimes the plug threads may be dirty and therefore screwing them in may take some effort. I tried to again to make sure and it screws in and out but still with a lot of effort.

 

- After screwing in the plugs and when putting the coils back on, make sure that the coils are flush against the head. If there is any in/out play or spring-action from pressing on the coils, then plugs are not all the way in. Again I learned this the hard way, when I stopped screwing in my final plug too early since it was taking a lot of effort.

 

- You do not have to use anti-sieze. The Subaru vacation pix only suggest using motor oil on the threads and in doing so make sure to only apply 1/3 of the specified torque when screwing them in.

 

- When removing the intake, it is gonna make it easier if you remove the flexible intake connector first.

 

For me, the minimum required tools were:

- Extendable magnetic wand and tray (Life savers)

- 10mm 3/8 drive with at least a 10inch extension for the intake

- 10mm wrench for the bolt holding the intake

- 12mm 1/4 drive and 12mm offset wrench for the coils

- spark plug socket + univ joint + >=4 inch extension 3/8 drive to unscrew plugs

- Pliers to pull spark plug socket off plug after screwing back in

Finished mine today and the rear coilpacks are hard to get back IN over the plugs. The trick I found out was to disconnect the wire harness going the the packs as it makes adjusting them much easier,..Also, I could only get a torque wrench on the front 2. Im sure if I had the in2 wrench, it would have been easier,..

 

I noticed too that the rear driver side coil pack bolt came out all corroded. I wonder if the dealer removed and didnt tighten it down or forgot when I went to them for an idling problem last year. They ended up changing the fuel injector and my problem went a way. In any case, my car pulls much harder and with much more response which has me thinking if this may have been a problem.

Actually, the 1 step colder NGK plug that is most often used is LFR7AIX.

 

Changing plugs on a Subaru isn't a lot of fun, but I can usually get it done in about 45 minutes.

 

I leave the battery in, but usually take out the airbox. The rear coil packs can easily be extracted from the top if you detach the wiring plugs, pull the coil packs off the plugs, then rotate them 180*. They pull right out then. To get the rear plugs out, I use a spark plug socket with a 4" extension. Loosen the rear plugs till there is just a thread or two engaged and pull out the extension. Then stick a finger in the end of the spark plug socket and finish pulling out the plug. If you leave the extension in the socket on some cars there is not enough room to the frame rails to pull the whole assembly out. The front plugs are straightforward. Reinstall everything in reverse order. Remember that the black headed plugs go to the rear coil packs and the white headed plugs go to the front coil packs.

When you disconnect the harness plugs from the coil packs to remove them you have to keep track of which plug goes to which coil pack for re-installation. They are color coded. The plastic connectors for the front coil packs are white, the ones for the rear coil packs are black.

There is a better way to remove the rear drivers side coilpack. Fist you unclip that black padding next to the coil pack. 2nd, unplug the black connector on the coil pack. Finally you can easily remove the coil pack from the top easier than the bottom by rotating the coil pack.

Just did mine a couple of hours ago. It took me much longer than it should have (~2.5-3 hrs). I spent most of my time trying to get the drivers side rear coil pack on. Both fronts slipped on real easy, but both of the rears were tough. I was able to get the passenger side rear on after some fiddling, but the drivers side was a nightmare. Here's the trick that I found worked. I was able to stick my sausage fingers in to where I could feel the tip of the spark plug. What was happening is the rubber shroud of the coil pack was not finding its way onto the tip of the plug but rather under or above it. I was trying to force the darn thing thinking maybe it was a little snugger fitting until I stuck my fingers in there and could tell they weren't lining up right. What I found is this. when inserting the coil pack, you need to turn it 180 degrees like everyone here has already mentioned. Next you need to make sure you can here/feel that the rubber shroud has found its way onto the tip of the plug. Next, and this was the crucial part for me, you need to slowly turn the coil pack back 180 degrees (to clearify, you had to turn it 180 degrees the wrong way to fit it into place, now you need to turn it back 180 degrees so that it will be in the correct placement and the bolt will line up with the hole.) and make sure you don't disengage the tip of the plug from the coil pack. If you feel it disengage, then repeat and be very careful to make sure the coil pack stays on the spark plug tip. When I was careful I was finally able to get the coil pack onto the spark plug and it slipped on with relative ease. I hope this helps someone else not to spend 45 minutes trying to get the drivers side rear coil pack on.

 

Oh one more thing... When I first started the car after the install, the car wouldn't turn over. The starter was going, but the engine wouldn't catch. I turned the key off, then tried again and the car turned over fine and is running smooth. I'm guessing that because i took the battery out that the ECU reset and was dong somthing weird the first time I tried turning it over. Has this happened to anyone else?

Removing the Coil pack. If you have the right tools, the actual spark plug comes out and goes back in easy.

 

Did mine today. The pointers on this link were a big help. Maybe I can add a few details that may help make somebody day easier.

A) Antiseize on the plug threads-easier to remove next time and easier to install and less likely to cross thread

B) The "pads" on the frame. Use a simple screwdriver to pop the front attachment off and pull them up and out of the way. The little bit of extra room made a ton of difference on the drivers side. Spare yourself a lot of unnecessary ag pop them off and tip it up.

C) As for the pull the battery -not pull the battery argument. If ET is you friend call him over and give him a beer. If you have normal human hands ... pull the battery . Too much crap in the way for me. I could not get a second hand down w/o pulling the battery.

The next time I do this will be quicker but I dont think I could get this down to the 35 minutes that some people quote. My hat goes off to you.

Ugh just finished doing mine. Old plugs with 52k looked good as far as I can tell. My biggest problem was the plug socket became really stuck on the newly installed plug on the passenger side rear. I spent 25 minutes with trying to get the socket off the plug. My other major problem is that I did not any appopriate 2" extension and had to use a universal where a 2" extension would have been MUCH easier to work with for plug removal and install. I think a 2" extension is key.

 

It took me 3 hours including battery and intake removal and reinstall. Started engine and took it for a drive. No detectable difference from before, which is a good thing, I suppose. I put in the NGK 6619's (LFR6AIX-11).

Depends on your level of technical ability, access to tools, etc.

 

I did my DP (had a 2nd OEM DP already gutted), and after getting that far, decided to skip doing the UP - it took me like 6-7 hours to do the DP. Yes, this was my first time working on a Subaru, all the steps were new, etc. And, I'm not super mechanically inclined. But, it would have taken me another 2-3 hours just to get the UP loose, IF I had managed it - I needed the car on Monday to go to work :-) Plus, having never worked on a turbo engine before, all the exhaust routing was new to me, etc. Didn't want to mess up a gasket by hurrying, and then having leaks all over the place.

 

All that to give you some context: I did my plugs in 3-4 hours (first time doing plugs), and most of that was struggling to get the caps back on the plugs after they were installed - that's a bit of a tight fit. DO buy at least a wobble or U-joint ratchet extension. Don't think you'll manage without one. I ended up doing the following: loosening with ratchet + regular extension + socket. Unfortunately, the fit it so tight, the ratchet wouldn't fit for more than 1/4" of threading. So then, I used the wobble extension + fingers or vice grip pliers to get the plug out the rest of the way and the new one in part of the way until the ratchet + regular extension fit to tighten up.

 

If you've done UP/DP, I would say it's only half as much work, or less.

Just finished changing the plugs on a 2005 XT outback. Thanks so much for this thread. Here are my few hints:

 

1. Battery and air filter box removal a must for my year

2. Remove the one 'button' that holds some type of fireproof matting on the fenders on both sides. The button is up toward the front. Just pry it off but don't rip the matting. It doesn't look like it will add much room, but it makes the world of different. They just rotate down and out of the way.

3. No need for 1/4" driver. I just used a regular wrench with a slight bend (offset wrench). A good collect of extensions pretty nice to have.

4. The swivel joint (universal, whatever) makes life much harder. No feel and it binds. I can't imagine trying to feel how tight the plugs are with that thing, and the binding wouldn't give good torque readings. A 2" extension with a 5/8 spark plug socket works perfect. Just pull the ratchet off before you back the plug out all the way or you can't anything out.

5. Passenger side rear was the hardest one for me

6. 180 deg twist didn't work for me, but I did have to twist them in all kinds of different ways to get them out. You have to unplug them! I was under the impression some people didn't unplug all of them. No idea how they can do this without unplugging them

7. anti seize compound on the new plugs makes threading them in by hand real nice and gives good feel for tightening them.

8. There is no feeling or click to putting the boot back on. They just slide on and that's that. I was nervous since I expected SOME feel to that... No issue with sliding on the boot. Just went on...

 

I do think that this year must be easier than earlier years since it wasn't too bad. Not a lot of room, but enough.

 

I am fairly mechanically inclined, have done spark plugs on a number of other vehicles (including Ford Ranger with 8 plugs for 4 cyl that are HARD compared to this) and was nervous about doing it. I shouldn't have been.

 

Time = 2 1/2 hours

Did my first set of spark plugs ever today. I was anxious to do it previously, but reading this thread really helped.

 

Helpful cliff notes for me:

Little space to work, so make it easier.

Have the tools; 5/8 plug socket, 3" and 4" extension, U-joint, offset wrench, anti sieze lube,... Its a small cost for the saving of time, frustration and/or additional money.

180* rotating of the rear coil packs for removal/install really helped.

Remove battery and airbox, its not difficult and saves time/knuckles.

Otherwise the directions are simple, just take your time.

 

The plugs I removed today looked very good for 35k miles of use (93k miles currently), running a little rich maybe. Next, I'd like to get off cobb's ots maps and/or start logging asap. I had a slight stumble at idle, not sure if its totally gone yet, we'll see.

 

Thanks for the thread.

I'd like to add one step to this that makes the rear plugs easier.

 

There is some sound deadener insulation on both front frame rails. Take the forward most clip out and let the insulation hang down. It gives you another 3/16-1/4" of room between the frame rail and cylinder head to get your ratchet in there. When your done, just reinstall the clips (they are reusable). Every bit of room helps!

 

OP, maybe you can update you walk thru? Doing this saves me about 20 minutes total on the job.

Put the car up on drive-on blocks, did the drivers side just as fat as the pass side, did not remove battery, did it all from underneith. Highly recommend doing drivers side from under side , pass from above. Took 1 hr.

 

Plugs were in bad (worn but no signs of engine isues) shape, 40k on them.

 

Rear set of coils are starting to rust, both of them. Coils are actually spreading apart due to the corrosion. Anyone else having that issue yet? 123k on the car, but bottom engine cover, "skidplate", has had a missing cover since 40k...Look just like this one:

http://legacygt.com/forums/showthread.php/bad-coil-pack-looks-like-67194.html

Dude... no doubt that the driver's side rear was a real PITA. I beat my hands to hamburger trying to get it all back in and then had a realization. It took about 10 mins to take off the bottom plastic pieces and loosen the LH engine mount. 30 seconds later I had it jacked up a few inches and HOLY COW it went in like butter.

 

I highly recommend that when you do this install that you considers just loosening those darn engine mounts and jack it up a few inches. 10 minutes of extra work up front will save you 45 mins in the long-run. I'm just saying...makes all the difference in the world!

Changed plugs this weekend. Things are a bit tight, but the job wasn't too bad.

 

Key piece of equipment? A hex drive to socket adaptor, like you would chuck into a drill (similar to the pic).

 

I ended up attaching this to the 5/8" spark plug socket and it gives you enough something to hold onto when you are seating the new plugs back in. Hand tighten them a bit and then you can pull on the drill bit piece and the whole spark plug socket will come out, leaving your new plug partially screwed in. The fact that it's screwed in a bit gives you enough clearance to now attach a short extender and universal joint to the sparkplug socket, reattach the setup to the plug, and torque it down.

Replaced mine today thanks to this walkthrough. I never found any particular part difficult, it was just time consuming in general. Took me probably 2.5 hours but it's not like I was in a rush.

 

I bought this spark plug socket which made getting the plugs out pretty easy, even the driver's side rear.

 

As far as putting the plugs back in, I did have to get them started with a normal spark plug socket and a drill bit adapter.

Thanks for all the tips everyone, I'll let you know how it goes.