P0304 Cylinder 4 Misfire did tune up, Injector next? 2003 Outback 2.5

[Spiney]

Hi, I'm trying to fix an issue with our 2003 Outback 2.5L Automatic 143K miles.  Started with a regular CEL, then elevated to a Flashing CEL.  Car would idle rough when it was damp outside and or cold.  This is what I've done so far.

When car was running well and it was dry outside I spritzed water, very lightly around the engine to re-create the problem.  The very first place I hit caused the problem.  I spritzed some water on the Coil Pack module, immediately a spark started jumping from Terminal 4 to the mounting bolt nearest the terminal.  It was a very big spark and from my point of view it appeared like there was a crack in the terminal.  I purchased a replacement and replaced the original with a brand new piece. The #4 terminal was blackened on the original coil pack.  I did notice the connection from the spark plug wire on this terminal was looser than the others.   I crimped it slightly with a terminal crimper and re-installed all of the wires.  At first I thought I had it fixed, but not very long as the car sat idling the rough idle and the same spark happened from the same terminal to the mounting bolt.  My first thought was to coat the mounting bolt and the end of the spark plug wire at Terminal 4 with Silicon RTV.  This held up for a few days, but again, as soon as we had some rain, I had the same issue. I also ran the tank down to near empty and put in a bottle of quality, can't remember the name, Fuel System Cleaner, then filled the tank with 87 Octane Sunoco

So went to Advanced Auto and per recommendations on the web I replaced the wires with a set of NGK, and a set of NGK replacement plugs. I went for NGK plugs that were for my car.  The Autozone system came up with NGK G, which I found are Platinum tip.  I've since read that I should have gone with copper.  Is this a real issue?  I used dielectric grease on all connections.  I used Permatex Anti-Seize on the plugs.  The number 4 plug looked like it had un-burnt fuel on it.  The original plugs felt like they had been torqued too tight, but had no signs of stripping.  It was just hard to break loose and I had to wrench them a long time until they were finger loose.  Not having a torque wrench I put them in finger tight, then wrenched them 1/2-3/4 turn snug. I took the car on a quick local shakedown drive and it felt great, had more power than it had since we bought it.  2 days later we drove it much further, about 50 miles each way on the PA turnpike at speeds up to 75 MPH.  No CEL's car felt great until...

On the way home we were stopped by an accident.  It was in the 20's outside.  We sat idling for almost 30-45 minutes.  As we were pulling away from there, the car started running a bit rough when de-celerating.  Then about 10 minutes later as we sat in line to enter the turnpike the idle started getting rough and the CEL came on.  My wife was afraid to drive it the remaining 35 miles home, but I said it's not flashing, and when we stopped it was OK if we put the car in neutral.

When we got home I ran the car at idle in front of our home, about 30 degrees now.  It was dark and I was looking for evidence of sparking again, but saw none.

I've read through several threads on this issue on another Forum, before I found this one.  They suggested after a tune up was performed that it's the Fuel injector if I'm lucky, or burnt valves if I'm not.  Or possibly the small chance that the same plug or wire is bad again.  I'm hoping that since it ran so strong for over 60 miles at speed and at idle that it's not the valves or head.  I really pray that is true, because I don't have the money, or skills to repair that.

So if you were me, where would you go from here?  If the next step is the injector is a re-manufactured one OK?  Which Brand?  While i'm in there is it foolish to not replace both injectors on the drivers side of the block?  I really would rather not buy 2.  Everything seems to point to Cylinder #4.

BTW, While I spent the last 20 years as a photographer, I went to school for electronics and feel comfortable around a DVM.

Thank you in advance for any replies, I really appreciate any helpful feedback.   Spiney-Dave

[AdventureSubaru]

What code did you get the second time? Is it the p0304 again or something else?

[idosubaru]

the injectors are actually really easy to swap - easier than changing spark plugs, given what you've already done you'd have no problem just swapping #4 and #2 injectors. 

 

if the condition moves with the fuel injector then you isolated the issue to that specific injector.

 

if it's valve related then check valve clearance, unfortunately the #4 cylinder exhaust valves do occasionally get too tight, too hot, and burn. 

http://www.ultimatesubaru.org/forum/topic/112173-ej-non-turbo-burned-exhaust-valves-consensus/page-3

[Numbchux]

Step one is to figure out what code you're getting now. The car is trying to tell you what's wrong....

 

 

ASSuming it's a P0304 again, I think you should try your water spray test again. It's possible that the casing on the coil is cracked and still arcing to the mounting bolt.

 

 

If you can't recreate the symptom, or don't see any arcing, the next thing to try is to swap injectors between 2 and 4. This is not a difficult job, just be aware that the OE injector "O-rings" are expensive (like $15 each or something), so be gentle with them, they're almost always reusable.

 

If you still aren't getting a change, a compression test might be a good idea. In my experience, a burnt valve isn't an intermittent symptom, and will definitely show up on a compression test. A sticking valve can be intermittent, and may not show, so that might be hard to place if that's what it turns out to be. 

 

 

Original plugs in that engine were Champ RC10YC4, which Subaru superceded to an NGK BKR6E-11, both are a Copper plug. The Platinums probably won't cause a problem, but I wouldn't plan to use them any more than the recommended 30k miles for the Coppers.

Edited December 21, 2016 by Numbchux

[Spiney]

Thanks for the replies. The Code is P0304 Cylinder 4 Misfire. I drove straight to AutoZone for a read while it was lit. I'm going to check out videos on how to replace fuel injectors and then try a 2-4 swap. I'll let you know ???? what happens.

 

To reset the CEL I need to disconnect the battery, correct? For how long? TIA, Spiney-Dave

[Fairtax4me]

Arcing from the plug wire will leave a carbon track on the post of the coil pack and will cause it to continue arcing even with a new wire.

Whenever there is an obviously burned connection like that both the coil and wire need to be replaced to prevent a recurrence of the problem. Recheck the coil post for arcing.

 

Single platinum G power plugs aren't the best for the ignition system design on these cars.

Use NGK Laser double platinum or Iridium plugs. Or plain copper or V power copper plugs.

[Caboobaroo]

I rarely see the injectors fail on this era of Outback so I doubt it's that. Like it was said, check the coil pack and if it needs replacement, use only an OEM Subaru coil pack. Aftermarket units have a high failure rate.

 

If it comes back with the same misfire, I would pull the valve cover and check the valve clearances.

[Spiney]

I think I found & fixed the issue. I removed the washer tank preparing to swap the injectors, when I noticed the #4 spark plug boot was not properly seated. This would explain why I was hearing a ticking sound in that area but saw no spark. I made sure it was firmly seated. Did a test fire ???? and put everything, including the fuel ⛽️ pump fuse back together. The CEL is out, car ???? sounds strong. Will take it on a shakedown cruise tomorrow. I thanked God for helping me find something simple and avoiding more expense.

 

If all goes well it's another example of Hakim's Razer or whatever the proper name is "sometimes the simplest answer IS the Answer.

 

Thank you all. While there are better things I'd rather be doing 4 days before Christmas ????, I am learning my car ???? and putting another punch in my Man Card, lol ????.

 

I had a 75 Saab 99 EMS body with a transplanted 78 Saab 99 drivetrain. The 78 coupe was perfectly maintained with a books worth of service records when I was rear ended and it was totaled. So I found someone who transferred the drivetrain in a Barn Find 75 EMS Body.

 

Anyway, I knew that car thru and thru. Knew which relay to jump when it wouldn't start, knew practically every component in it. I don't want or need to be that way with this Subaru, but it helps when your stuck, or you need to trust a mechanic.

 

Thanks again, Spiney-Dave