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1997 Subaru Outback Misfire on all Cylinders


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I'm to to this Subaru Group but I am hoping I can get some Ideas on where to start. I have a few but would love some more input. I have a 97 Subaru out back as mentioned that has a misfire on all for cylinders. I have changed the wires plugs and coil pack. I just recently purchased the wire harness that runs to the coil pack hoping that there might be a short in the harness causes the coil pack to burn up. When I replaced the coil pack I had the codes cleared and it ran for about a day before the check engine for the misfire returned. I haven't replaced the wire harness yet. I have recently read that the harmonic balancer could also be the culprit. I have not taken off the balancer but was going to do that tomorrow and take a look. Any advice is appreciated. 

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NGK Copper Core plugs and NGK or Subaru Plug wires, hopefully you these. 

What did the old plugs look like?

 

The MAF can be cleaned and could be the cause of a misfire. 

 

Subaru coils are pretty reliable, and usually one side of the coil goes bad causing a misfire on 1&3 or 2&4.

 

What's the mileage?

2.5 DOHC or 2.2 SOHC engine?

Please list the codes. 

 

Unlikely that the harness is bad and the engine harness goes to everything on the engine.  To replace it you would have to pull the intake off.

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a small correction to what larry posted,

the coils usually fail front vs. rear,

that is 1&2 vs. 3&4.

the coil is actually 2 coils,

one for the front cylinders and one for the rear.

 

a timing problem will sometimes cause a left vs. right cylinder misfire.

 

after you rule out some of the easy stuff and find no cause for the problem,

plugs, wires, loose connections, dirty air filter, etc.

consider checking the timing and /or the compression.

if the belt jumped it could cause a headaches.

 

plug wires cause more misfires than all other stuff combined.

not a scientific fact, just my opinion.

Edited by johnceggleston
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It is a 2.5. That is the thing is that it is misfiring on all four. I will get the codes again. I believed the last plugs and wires i used were NGK. Havent checked the MAF yet but I'll look into that as well. I am aware that I have to take off the intake and that is why I figured I'd see all my options of what to do before I pull the intake and the harmonizer. I love working on subarus but haven't had a misfire like this before. I also did an engine swap from a 99 subaru limited into a 97 subaru outback. I wouldn't think that would matter but figure I'd put that out there as well. I'm sure It's not the plugs wires and filter as I got all new when I did the swap. I also haven't checked the timing or compression. That would most likely be something I take it for the shop for as I'm am not the most skilled mechanic and I'm using minimal tools as of now. Thanks for the help.

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I just think It's weird that it ran great for a day when I changed the coil pack and by the time check engine returned it was misfiring on all for again. That is the only reason I have been leaning towards something that is causing the coil pack to spoob out. ecu or wire harness but once again that's why I'm on here is to get some more genuine Subaru input. What type of headaches would I be looking at if the belt jumped?

I will check all the small things and let you know how it goes.

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If the timing is off far enough you can bend valves.

If you have a cam and crank sensor you might want to swap them one at a time and see if the problem goes away.  They usually fail completely and then there is no spark, but I have seen them do strange things.

 

It would be worth hooking up a computer and seeing the signals to the ECU before you pull the intake.

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yeah when you have all cylinders miss-firing you have a wider issue like timing, knock sensor or MAF.  if your belt jumps on tooth you wont get a cam or crank sensor code but it will miss-fire.  the problem is that you have to take the harmonic balancer off to fully inspect. It can be dead on at the cams but a tooth off at the crank which you cant see unless you drill a hole in the timing cover :) have seen this a couple times and it baffled the dealer mechanics for weeks. Then I got the "stump the chump"... wires, coils and stuff like that usually  cause a singular or like previously stated 1/2 or 3/4 miss-fire scenario.  

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By misfire on all four, do you mean that you are getting a random misfire on all four with a P0300 code?  If so, I would start looking at the crankshaft position sensor or cam position sensor, but I'd bet on the crank.

 

If you are getting stumbling with no code, then I'd lean to the MAF.

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  • 2 weeks later...

Thank you all. I have found the misfire. I used some MAF cleaner and changed the crank sensor and poof no more misfire. I believe it was the sensor. It had a layer of dirt and crud on the bottom of the crank sensor. I would guess that having the layer of crap would effect how the sensor functioned. I am so happy that I did not have to do the timing belt after talking to a few people that have done them. It sounds exhausting. I also replaced the parking brake shoes and springs. I pulled off my back rotors and the pieces just fell from the parking brake. I now have a new code that is reading about my purge system,. Was thinking of replaced the filter and the solenoid and start from there. I don't know if any of you have had experience but I read that if the vapors are't being moved properly that it can cause rough starts which I am still a victim of. any ideas?

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Was thinking of replaced the filter and the solenoid and start from there

No, that's not a good place to start.  First, it could be the gas cap.  Second, for that old of a car [and I have 2 that old] you have to consider that there is a leak in the gas filler tube.  Try and see if you can smell gas around the rear passenger tire after a fill up.

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  • 2 weeks later...

The last time I filled up I didn't smell any odor of gas so gonna check the lines and get a new box and then change the solenoid but my check engine was flashing like before and I ran the computer and I have 3 codes and two of them are cylinder 1 and 2 misfire. I didn't think to write them down but I will get them tomorrow. I just purchased new NGK plugs and wires. I'm going to change them in the next few days and then change out my cam sensor if the misfire shows up again. Any other Ideas or info is greatly appreciated. 

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