Cylinder #2 Misfire & check engine light blinking just when idling

[Gecko1650]

Hello all,  I have a 1997 Subaru Legacy Outback and I'm having a P0302 Misfire. Ive just checked the spark plugs and wires and they both seem good. I replaced the plugs also because why not. No change. My check engine light is flashed only when idling and warmed up. Give it some gas and it will go away. Ive tried to find a vacuume leak via carb cleaner, Nothing. Changed Plugs, Nothing. Checked Wires, Nothing. Took it to a shop and they said it could be a clogged Cat or O2 Sensor. Will a bad front O2 sensor or clogged cat trip a flashing CEL/ Misfire on just one cylinder.  Any suggestions would help, not trying to replace everything just to find the problem.

[Bushwick]

I was going to say O2 sensor even before reading that a shop said the same thing. Are you getting ANY O2 codes? In short, an O2 sensor shorting internally CAN and cause misfires, but usually it's a random misfire. I had this happen on my Saab which had a heater element fault in the rear/2nd O2. Car ran fine otherwise so it was ignored for awhile. Eventually, a random misfire would happen, often within 5 minutes of starting the car. Pull over, rev, it'd clear and be fine. Eventually while driving one day it did this, I revved to 3k and it backfired something nasty. Car was cat-less at the moment (thankfully). I pulled over and inspected thinking it dropped a pipe, only to find the muffler looked like an M80 went off in it! 1 year old muffler completely separated at the seams and went from oval to round- never saw anything like that before. Didn't damage the turbo or anything else but the muffler. I replaced BOTH O2 sensors after that and the misfire went away.

 

O2's are cheap for Subaru and they'll probably get you a bump in MPG if original, but can't guarantee it's your issue, but won't hurt to replace. Since it's a P0302, I'd look at the plug wires 1st and maybe a failing coil. Just because the wires "look" OK or are a year old, doesn't mean they are any good. Especially if they are cheap wires. Can try switching the wires for one side (switch both ends obviously) and see if the P0302 turns into a P0304 etc. Remove the battery cable to reset. Also look for plug wire chaffing on ANYTHING metal. Might be grounding out. If you can find a coil a junk yard for cheap, try swapping it in and see if the issue persists or goes away. If nothing changes after all that, might want to try new O2 sensors. rockauto has them for pretty cheap prices. Do NOT get universal O2 as they can be troublesome. Be glad it's not a Saab where my O2 cost $80 EACH and are closer to $120 EACH at the parts store!

[johnceggleston]

i know you have checked the wires,

but wires are the leading cause of misfires.

move the #2 wire to the rear, #4 and see if the miss moves with the wire.

 

if yes, replace the wires.

if no do a compression test on #2.

[Fairtax4me]

What John said.

 

Burned exhaust valve will act just like this. Has the valve lash clearance ever been adjusted?

Could also be jumped timing.

Check simple stuff first though.

[okamikai]

Usually when CEL flashes is an indicator of a major combustion issue, if O2 sensor is reading an annomally it will throw code. Compression test should be done to rule out a worn out cam head gasket, also unusual combustion causes the spark plugs to stain if it is burning something other than fuel and air mixture, normal spark plugs should look white-ish with no oily deposits, just zoot, and just as John said, don't rule out the wires or the coils.

[luko]

Run a resistance test on the coil to check for continuity, and do the same thing for the wires. If you do end up replace the coil and wires make sure you use OEM parts like Beck Arnley  

[Gecko1650]

I checked the Plug Wires by switching them, Didnt seem to make a difference. I dont have a Multmeter or anything to read the resistance on the coil. I did unplug the the #2 wire from the coil and it seemed to have spark. I also unpluged the front O2, drove it around for about 15- 20 mins and it acted the same, no difference. The CEL still was blinking when idling. 

Truth be told I bought this car for super cheep from a friend because he bought a new Sub and never drove it the old 97.  I got it for $250, its in pretty good shape but has 251k on the clock. It really runs pretty good besides the misfire. I really just want to use it as a winter beater but it would be nice to fix this misfire as cheep as possible. I'm not opposed to getting new basic parts if it needs replaced and stops the misfire. But if its anything internal I would rather just put in a 2.2 or a 2.0 because that would really be cheeper in the long run. Can I clean the Cat and O2 to see if that would make a difference before forking out $$$ to replace them. I have a 2003 Outback that my wife drives and a 2005 Outback that I can drive also so the 97 Outback doesnt have to be perfect. Dont know if any of that made sense.

[Fairtax4me]

O2 probably isn't causing this problem (it would cause all cylinders to misfire rather than just the one) and there's no way a cat would cause an issue that happens only at idle.

Try cleaning the MAF sensor, (use MAF sensor or electronics cleaner) check for any loose or split vacuum hoses and make sure all of the intake piping is securely connected and all of the breather hoses are attached where they should be with no split ends.

That engine does have EGR and its possible the EGR valve could be stuck open and causing a misfire, but that would usually result in multiple cylinder misfires. Since this is just one cylinder, this points toward a mechanical problem, or possibly fuel injector problem specific to that cylinder.

 

Check valve lash. If either of the exhaust valves on number 2 has 0 lash that valve is probably burned.

 

I'd say do a compression test, but its a PITA to do on that engine.

[johnceggleston]

 

I'd say do a compression test, but its a PITA to do on that engine.

 

true, but #2 is easier than #4.

 

there was one guy who had a bad cylinder, and miss.

he just unplugged the injector and drove on 3 until he got around to fix it.

if the cat / o2 code is because of the misfire,

that might go away if you turned off the fuel.

Edited October 18, 2013 by johnceggleston

[ivans imports]

Had a wrx that was doing this last week vilently under load was the screeen on the intank feul pump was pluged and no feul was making it to pump low prehsure outputt was causing misfires. Try a Carter p74152HP feul pump is 260 lpr vs the stock 160 lpr pump have been using this pump to boost up feul preshre / volume shure fixed up that wrx

[jim milewski]

I have a similar issue going on right now, same year, just want to get throught the winter, made quite a few changes, igniter, plug wires, coil pack, still the flashing CEL, one thing I noticed was how white the plug was (lean???), so the fuel pump as ivan pointed out comes to mind, before i do it I'm gonna check the inline fuel filter. My flashing CEL comes on at 60mph, and the misfire made my post cat o2 sensor send code 0136

[Gecko1650]

So I unpluged the #2 Cylinder Fuel Injector and the flashing check engine light went away. Still acts the same, #2 Cylinder is missing. So I'm guessing that 1. my o2 is working to detect that I wasnt dumping fuel in the cat anymore causing the blinking check engine light.  2. my problem is likely no spark or weak spark or mecanical in cylinder #2. I probably clean the EGR Valve and the Mass Air Flow today or tommorw just to see if it makes a difference.  

Anymore ideals anyone?

[johnceggleston]

i would think if it were the MAF or IAC, it would affect more than just one cylinder.

but it can't hurt to clean them as long as you use the right stuff on the maf.

 

but i think a compression test is going to be more telling.

 

or hold a dollar bill over the exhaust pipe and see if it is ever sucked in.

this could indicate a burnt exhaust valve.

Edited October 20, 2013 by johnceggleston

[ivans imports]

+1 valve damage

[okamikai]

Sounds like it could be a bad or clogged injector, you should rule that out. A clogged injector will send poor fuel pressure into the cylinder, this could cause a misfire and a blinking CEL. Also, did you try changing the wires, spark plugs, and Ignition Module(s)? Its not an expensive job and may clear many doubts.

[Gecko1650]

I have not changed the wires and coil yet.  I know the coil is old. Its also missing a bolt on the side of the misfire. Not sure if that would do anything.   I'm gussing valve damage. I have the injector unpluged right now and it makes a whistling noise out of the tailpipe when I give it gas. Not sure if its a sucking noise from a burnt valve.

[Gecko1650]

just did the doller bill trick with the exhaust. Pretty sure its a burnt valve.  Well I guess we will see how long this EJ25 with 251k, a burnt valve and running on 3 cylinders last. Any bets?    After she blows it will be a 2.2

[Fairtax4me]

It'll still run forever as long as the rod bearings hold up.

 

The whistle is a Subaru thing. Something to do with the muffler. Gets much more prominent when you have a dead cylinder.

[timintc]

I had a 304 code this past summer on my 2000 legacy. On start up it idled rough but smoothed out once it got going. Long story short the 304 was just a precursor to a blown head gasket. Anti freeze was leaking into the cylinder causing a misfire until it blew completely. Worth looking into

[okamikai]

Well, repairing the cam heads is kind of less troublesome than making a swap, also 2.0 is meant for turbo; you will have less power if you don't install the turbo hardware, if you got the cash and the time then go ahead and do the swap, otherwise fix the cam heads, head gaskets, and head bolts so you can have a running car while you work with the 2.0. Always good to have it running, other than leaving you stranded when you most need it

Edited October 23, 2013 by okamikai

[Gecko1650]

I can get a EJ2.2 with less than 40k on it for $1,300. After putting new T-belt and gaskets on her I would say around $1,700 for a good low mile engine is a good deal. Not doing the 2.0 NA or 2.0 Turbo

[johnceggleston]

that is a whole lot more than i would pay to replace an engine.

 

i realize your situation is a bit odd,

since your ej22 engine has an apparent burnt valve,

but i would buy a used replacement engine from www.car-part.com.

find one that is close to home, ($300 - $600, much less if you go to a pull-n-pay yard)

and install it yourself. (free)

or have a shop do it, (6 - 8 hours of labor, so $500 - $800)

and do a timing belt & reseal front and rear before you install. ($250, plus labor)

 

a much better answer would be to buy a used head for $100 - $150,

add one head, plus intake and exhaust gaskets, ~$50.

and you are back on the road .

throw in a timing belt kit and front seals, just because,  ~$175.

less than $400, you'd pay more than that to have a shop change the timing belt.

 

so my estimate would be from $200, just a head, to $750 for a good used engine.

Edited October 24, 2013 by johnceggleston

[ivans imports]

I sell a resealed 2.5d with surfaced heads and all seals timing belt waterpump ect for 1500$ + install and cant keep them in stock. I do have about 40 2.5d heads if need parts

[okamikai]

wow what a goldmine, I'm screwed if I need parts like that, there are no Subaru salvage anythings here :/

[Gecko1650]

So I just pluged my #2 injector back in and I have tons more power and it seems to only miss and trip a flashing check engine code when I idling. If I give a tiny bit of gas the blinking stops. So Im guessing that when I'm idling its not firing correctly and pumping that unburnt gas in the cat. Give it a little gas and all is fine. So just by guessing that would mean that the O2 works because its reading the extra fuel, its getting enough gas because it triggers the blinking light which means its damaging the cat with extra fuel. Car still runs great except the tiny misfire at idle. This is so confusing.  Will a coil from a 2003 subaru legacy work on my 97 outback? Just to test if it makes a difference