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2000 forester auto
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45 Posts
Discussion Starter · #1 ·
Hello everyone I am looking for anything to check from this point forward. I currently have a 06 forester 2.5L non-turbo that I just did the head gaskets, timing belt and idlers, new plugs and wires. After hooking everything back up I am getting a PO304 misfire on cylinder 4. I have replaced the fuel injector to no avail, I have swapped wires from one to another, I have checked the coil pack for spark. I am at a loss for words and don't know where to go from here. The car did sit for about 6 months before I got it so I don't know if it's a fuel pump issue or filter. Every other cylinder operates like usual. Sorry if this is a duplicate post and I appreciate any and all help.
 

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2017 Forester XT Touring
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367 Posts
With everything else you've done, have you tried changing the spark plug in cylinder 4? Maybe you got a bad one, or some junk got into the gap/insulator area when it was installed. (You could swap the plug with another cylinder and see if the misfire moves, but at the cost of a spark plug, it isn't something I'd bother doing.)

Fuel pump or filter would be very unlikely to cause a misfire in only one cylinder.
 

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2000 forester auto
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Discussion Starter · #3 ·
@OutbackJon I have tried putting one of the old ones back in and it did the same thing. When I pull the wire from the plug it makes absolutely no change in the engine. When I pull the wires from all the other plugs the engine has noticeable loss of power. So I'm not quite sure with having a new plug, wire and injector where I should go. Is it possible that a MAP or MAF could affect just one cylinder
 

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2001 Forester
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2,605 Posts
If you pulled the plug wire on #4 and it makes not different, that tells me you have a bad plug, bad plug wire for #4. And that information would rule out MAF/MAP sensor. Where did you get the coil pack from? Is it the OEM or some 3rd party coil pack. NON-OEM coil packs are known to not work at all or work well. Note that Subaru's use the wasted spark system, meaning the coil ignites 2 spark plugs at the same time.
 

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2000 forester auto
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Discussion Starter · #5 ·
@bman400 I tried a secondary one I had laying around from another vehicle I did. I also pulled the wires one at a time and plugged a screw driver in the end as if it was connected to a plug and then held the rubber boot up to ground areas on the engine and checked the spark that way. Cylinder 4 is getting spark but I will say as I was pulling the plug from number 4 I would occasionally see spark jumping by the coil pack for that wire. Would this indicate a bad brand new wire??
 

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2001 Forester
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If you did not buy NGK wires, I would question the quality of the wires as well, other's here have used non-NGK wires without success.
 

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2000 forester auto
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Discussion Starter · #7 ·
@bman400 OK, I did buy NGK plugs but never really questioned the wires. I did try to swap one wire to another with no success. I guess this is going to be a trial and error situation. I just hate throwing money into thin air with no solution
 

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2001 Forester
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I have only replaced the plug wires on my 2001, maybe 1 or 2 times and it now has 222,300 miles. The last time I changed plugs I neglected to seat the plug wire probably and got mis-fire as well. I then had to pull each plug wire off each plug and reseat them, and that's when I noticed that one of them did not "click" onto the plug. After I re seated the plug with the click everything was fine. One thing you could do is take a DVM and measure the resistance on the plug wires for comparison, since the length of all 4 wires are almost the same you should get close OHM reading on all 4.
 

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2000 forester auto
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Discussion Starter · #9 ·
@bman400 OK I will try that, this specific year has the coil pack more on the passenger side rather than on top and in the middle. Thanks for all the suggestions, I will list the resistance after I get the measurements.
 

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2000 forester auto
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Discussion Starter · #14 ·
Not sure if same, but it's a starting point for you.

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Well I checked everything and all checks out. Now I am showing a PO082 code and from what I'm reading that is a variable valve solenoid. Problem is I don't know if that can cause a misfire on just 1 cylinder. The variable solenoid looks like a pain to get the one bolt out that holds it in place. If anyone has removed this without taking the entire timing cover and all components out I would love to hear how it was done
 

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2009 FXT
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Is your code P0082 or P0028?
You have to remove the Cam Position Sensor and bracket to get at the solenoid bolt, not to hard.

I've run into an issue several times with the AVLS assembly itself. Getting P0026 or P0028 codes but new solenoid or oil pressure switch didn't solve it.
What the problem was:
The AVLC assembly when removed has a basket oil filter in the oil port. This little filter can be aligned so the plastic rib that supports the filter element can be aligned with the oil flow port, restricting the flow somewhat. Once I realigned the basket filter so there is just screen in front of the port where the oil flows, I had no more issue

I believe this can cause misfire codes
 

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2000 forester auto
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Discussion Starter · #16 ·
Is your code P0082 or P0028?
You have to remove the Cam Position Sensor and bracket to get at the solenoid bolt, not to hard.

I've run into an issue several times with the AVLS assembly itself. Getting P0026 or P0028 codes but new solenoid or oil pressure switch didn't solve it.
What the problem was:
The AVLC assembly when removed has a basket oil filter in the oil port. This little filter can be aligned so the plastic rib that supports the filter element can be aligned with the oil flow port, restricting the flow somewhat. Once I realigned the basket filter so there is just screen in front of the port where the oil flows, I had no more issue

I believe this can cause misfire codes
Is that on a turbo model because this one I'm dealing with is non turbo. After replacing other parts I now only have a PO304 misfire cylinder 4 code. I have replaced plugs, wires and even the fuel injector to no avail. I did not replace the coil pack yet. Do you know how to test an 06 pack to see if it's working correctly? I did the test where you pull the wire out and run it and use a screw driver in the boot end to act as a conducter and touch metal on the car and I got spark but I'm not sure if it's enough
 

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2005 Subaru Forester XT
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29 Posts
This might be a useless turbo comment from me; but i had a crankcase vacuum hose which wasn't connected properly, causing a small leak, and i suspect this caused a misfire. The misfire was on cyl 2 and 4, but not 1 and 3. no idea why.
i replaced a few parts and put in better fuel, so i cant say for sure this was my cause but it seemed the most likely culprit.
 

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2000 forester auto
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Discussion Starter · #19 ·
This might be a useless turbo comment from me; but i had a crankcase vacuum hose which wasn't connected properly, causing a small leak, and i suspect this caused a misfire. The misfire was on cyl 2 and 4, but not 1 and 3. no idea why.
i replaced a few parts and put in better fuel, so i cant say for sure this was my cause but it seemed the most likely culprit.
Yeah for some reason or another I can't find any vacuum leaks anywhere. I have replaced just about everything except buying a brand new motor out of the crate. Replaced parts are timing belt and pulleys, water pump, pcv valve, plugs and wires, a fuel injector for cylinder 4 that is misfiring, new MAP sensor and MAF, I tried a new coil pack to no avail. I tried swapping wires and it still shows cylinder 4. New head gaskets as well so those are fine, does have great compression. The car did sit for about 6 months from previous owner so I don't know the history on the fuel or pump but it does start and revs up fine, and on start up it idles smooth until the computer kicks down the fuel/air ratio due to warning up. I'm at a complete loss because the only code I get is the PO304 and nothing else
 

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2000 forester auto
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Discussion Starter · #20 ·
This might be a useless turbo comment from me; but i had a crankcase vacuum hose which wasn't connected properly, causing a small leak, and i suspect this caused a misfire. The misfire was on cyl 2 and 4, but not 1 and 3. no idea why.
i replaced a few parts and put in better fuel, so i cant say for sure this was my cause but it seemed the most likely culprit.
I'm just wondering if it's an internal ECU problem that might not be sending the signal to fire cylinder 4! I really have no clue as to where to go other than have the local dealership basically charge me to undo everything that's been done and if that's the case you guys can keep your eyes open because it might become a part out🤷‍♂️
 
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