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Guest Message by DevFuse

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Need some thoughts on forester issues

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7 replies to this topic

#1 MangleSon



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Posted 03 July 2014 - 08:41 PM

Got a 2003 forester that has a list of problems.

About 6 months ago it started sounding bad like there is something wrong with the exhaust.

My car for a long time would occasionally, almost rarely, hesitate a tad on acceleration. Didn't bother me so I never looked into the possible issue. A few months ago the cel came on when the car would chug on acceleration. Codes read 3 misfires. This has turned into a popping sound like a back fire while chugging. For a while I could finesse the gas pedal and not have much problem. Obviously it didn't fix it self. Had a buddy help me clean up what I think is the MAF and interestingly it ran well for a couple blocks then started up again. Later I got all four plugs replaced and it drove great for 30 miles and then started up again. Now it reads 2 misfires.

I replaced the ignition coil with zero change. The wires "look" fine... Plugs come out with a little oil on them. Last time I looked I think one came out looking O K. One came out with the white residue and one with the dark. The fourth didn't come out since it's a pain to get in and out and wasn't fixing my problem...

Any thoughts would be greatly appreciated. Thanks in advance!!

Steve loves his subaru! Even more when it runs great!

#2 idosubaru


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Posted 04 July 2014 - 01:00 AM

how many miles?

overall condition?


by three misfires - you mean "Cylinder 3 misfire" or three different cylinders are misfiring?


cylinder misfires:


1. plugs - this engine isn't very forgiving of non-OEM plugs, should be original NGK's spec'ed for an EJ25.

2. wires - same, they're not forgiving of cheap wires


if multiple cylinders are misfiring then:
1. coil pack

2. timing belt tensioner

#3 lmdew



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Posted 04 July 2014 - 07:20 AM

Change the valve cover gaskets and spark plug tube seals to stop the oil from getting into the plug wells.

#4 idosubaru


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Posted 04 July 2014 - 02:59 PM

oh yeah, he's got you covered. 


 Plugs come out with a little oil on them.


points to exactly what he said - spark plug tube seals.  replace them.

#5 unibrook



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Posted 04 July 2014 - 08:12 PM

How many miles on her?

Replace the front oxygen sensor if the misfire only happens when engine is warm.

#6 MangleSon



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Posted 05 July 2014 - 05:42 PM

Thanks for all the info!!

Some more follow up answers/questions.

It has 130k miles. It has severely overheated, but after I was able to get more coolant in it, it drove fine. No serious oil leaks to speak of.

It will do the chugging popping at any temp, starts as soon as start it and take off. Idle is kinda rough, it won't do the backfire pops but it was tripping the cel. Since last battery pull I drove the car a block or two and experienced all symptoms mentioned but the cel did not come back on yet...

And by 3 misfires. I am saying that 3 cylinders were misfiring, all but cylinder 2. And has since moved to only cylinder 1&4.

Just pulled the plug on #1 and it has some char marks from I'm assuming some kind of electrical arc on the porcelain part where the rubber connects to the plug. The other 3 plugs appeared to be in ok shape. No bad residue buildup.

I will be replacing all the gaskets to fix the oil on the plugs issue. But I'm assuming I have more going on then that. And that the oil is not the cause of the most severe issues...

As far as the type of plugs. I got the double platinum ones, seemed like the best that auto zone had. Are those ok or do I need to get something really specific? Not sure what NGK means? I believe the wires are the original.

Is the mentioned "coil pack" something different then the part I'm calling the "ignition coil". The part I replaced was the little box on top of the engine that the four sparkplug wires plug into.

Again, THANKS!!

#7 heartless


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Posted 06 July 2014 - 07:40 AM

NGK is a brand name, like Champion or Autolite.


And yes, a Subaru is VERY finicky about what kind of plugs and plug wires you use - especially the EJ25s.


Proper plug for your 2003 2.5 should be NGK # BKR5ES11 (new number 2382) gapped at .044 - check your owners manual for verification.

NGK does make platinum versions, but to be perfectly honest, they are little more than a waste of money if they are not specified for use in your car in the onwers manual.


Plug wires should be either from Subaru, or NGK - for your car, NGK part # FX58 (new number 8691).

Old or cheap aftermarket wire sets are a known cause of a multitude of running issues.


"coil pack" and "ignition coil" are one and the same

#8 brannos



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Posted 20 August 2015 - 10:43 PM

New to this forum thing . I have similar issue with a 05 ej25 forester, just had tappet gasket replaced and new nkg plugs and nkg Leeds . As they were oil soaked from gasket failed. Then had a new problem show afterwards that a cylinder was not firing at idle after warm up . Did the whole leed and plug swap to check for faulty items to no change ran copious cleaner directly and through fuel no change . Help

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