Mis-fire Codes P0301 & P0302

[mrwitty_1]

1996 Subaru Outback 2.5 Auto

 

I have developed mis-fire codes for cylinders 1 and 2. I changed sparkplugs and must say I could not find (like the story of Goldielocks) a socket, extension or combination of both to remove or install #4 plug. I checked resistance of the ignition wires, which appear to be new and OEM and all fell with in specs. I still have a repeated misfire code for the same cylinders. I am leaning toward a ignition coil failure, because 1 and 2 share the same pack, but I'm open to suggestions, I have owned many previous Subs and never had a coil failure, but I guess there's a first for everything. I don't drive this car much as it's the wifes car, but it seems to be in colder temps with-in a few miles of driving that it mis-fires. I have never had the mis-fire when I was driving and can not get it to miss (WOW ...a 2.5 winds tight when pushed hard) Anyone know if all 2.2 and 2.5 coil packs are the same? May try having the fuel injectors cleaned but still lean toward a ign. problem.

 

Thanks for any help.

[idosubaru]

coils can fail. the mis-fire codes are usually ignition wire related. they HAVE to be Subaru OEM wires on the EJ series engines (which yours is). they are not forgiving of aftermarket wires. they also need to be securely seated and removed/installed carefully. aside from that, the coil sounds like a good place to start.

 

if you wanted to really narrow it down you could swap plug wires around and see if the mis-fire "moves" with the wires, then you'll know it's the wires for sure.

[nipper]

The coil towers can get hairline cracks and throw the misfire code.

As grossgary has said, they really need to be OE wires.

 

nipper

[johnceggleston]

i have a new coil if you need it.

 

 

http://www.ultimatesubaru.org/forum/showthread.php?p=566907

 

let me know.

john

[murdoc158]

I've been chasing a similar problem for over a year now. I've got misfires on 1,2,3, but they move around from time to time. I've replaced the plugs, wires, coil pack, upstream O2 sensor, fuel filter, and air filter. I've cleaned the MAF sensor as well. Let me know what you find.

[Cougar]

1996 Subaru Outback 2.5 Auto

 

I have developed mis-fire codes for cylinders 1 and 2. I changed sparkplugs and must say I could not find (like the story of Goldielocks) a socket, extension or combination of both to remove or install #4 plug. I checked resistance of the ignition wires, which appear to be new and OEM and all fell with in specs. I still have a repeated misfire code for the same cylinders. I am leaning toward a ignition coil failure, because 1 and 2 share the same pack, but I'm open to suggestions, I have owned many previous Subs and never had a coil failure, but I guess there's a first for everything. I don't drive this car much as it's the wifes car, but it seems to be in colder temps with-in a few miles of driving that it mis-fires. I have never had the mis-fire when I was driving and can not get it to miss (WOW ...a 2.5 winds tight when pushed hard) Anyone know if all 2.2 and 2.5 coil packs are the same? May try having the fuel injectors cleaned but still lean toward a ign. problem.

 

Thanks for any help.

 

Before purchasing a new coil you could try swapping the two and see if that makes the misfire follow the coil.

 

One thing that may help with misfires is to run some Seafoam through the intake while reving the engine. It will help clean out carbon deposits if there are some in the cylinders.

[OB99W]

I have developed mis-fire codes for cylinders 1 and 2.[...]I am leaning toward a ignition coil failure, because 1 and 2 share the same pack, but I'm open to suggestions,[...]

Even assuming that this is an ignition-related problem (and the simultaneous cylinder 1-2 misfire would seem to suggest that), the coil pack of course isn't the only thing that can cause it. If you haven't seen these before, they might help with troubleshooting:

http://endwrench.com/images/pdfs/IgnitionCoil.pdf

http://endwrench.com/images/pdfs/DirectIgnition.pdf

http://endwrench.com/images/pdfs/Correction.pdf

http://endwrench.com/images/pdfs/IgnitionCoilSum04.pdf

The info in the PDFs above is a bit general; if you do resistance checks on the coil, what you get may not meet the spec in the articles. Since apparently your coil for cylinders 3-4 is okay, measure that first and use it as your "standard". If the measurements for 1-2 differ, then suspect a problem. Although an ohmmeter often won't show a problem (it often happens only under high-voltage conditions), it may be worth the time to do a leakage-to-ground test on the coil secondary windings in addition to the primaries.

 

 

Anyone know if all 2.2 and 2.5 coil packs are the same? May try having the fuel injectors cleaned but still lean toward a ign. problem.

There have been variations of coils packs over the years; for example, some have the igniter separate, while in others it's integrated.

[mrwitty_1]

Thanks for all the posts. I found the pdf's last weekend and checked my coil as per. the specs. my secondary points were all with in limits at 21.5 ohms, as for the primary points they were not in limits at 1.3 ohms but the temp was around 20*, winter has arrived here in WV. I didn't not replace the coil because both points 1-2 and 2-3 were equal. Now for the interesting thing, the mis-fire condition has disappeared, over a week and no mis-fire codes. I now think it is a current leak in the secondary ign wires regardless of there new appearance. I'll keep everyone posted. Any suggestions on a dealer or supplier for a set of OEM wires at a good price ?

 

Thanks ....

[idosubaru]

Any suggestions on a dealer or supplier for a set of OEM wires at a good price ?

Subaru only, there are some online subaru parts suppliers. do a search and look for subaruparts or 1stsubaru....i can't remember the names. some give internet discounts, so call and ask for internet pricing if they have it. get a price and ask if your local dealer will match it, sometimes they will.

[OB99W]

[...]I now think it is a current leak in the secondary ign wires regardless of there new appearance.[...]

One method of checking for that is to wait until dark, start the engine, open the hood and look for sparks. You could mist the secondary wires (and the coil) with water using a spray bottle; good insulation will tolerate that, leaky will usually become obvious when wet.

[julianfisher]

Thanks for all the posts. I found the pdf's last weekend and checked my coil as per. the specs. my secondary points were all with in limits at 21.5 ohms, as for the primary points they were not in limits at 1.3 ohms but the temp was around 20*, winter has arrived here in WV. I didn't not replace the coil because both points 1-2 and 2-3 were equal. Now for the interesting thing, the mis-fire condition has disappeared, over a week and no mis-fire codes. I now think it is a current leak in the secondary ign wires regardless of there new appearance. I'll keep everyone posted. Any suggestions on a dealer or supplier for a set of OEM wires at a good price ?

 

Thanks ....

 

If you have an update on your situation and what steps you took when the problem quit I would appreciate it.

 

I have been having the same problem for a couple months. It always comes when we are leaving town on the highway. After about a few miles the Engine light comes on. I clear and sometimes it will come back while other times it doesn't. When it first started I thought it was a good time to change the spark plugs. I did that and also changed the wires (OEM). But was disappointed to see the engine light come back.

 

I will follow the steps from the attached PDF's and see what comes up. Let me know if you know more about what curred your problem, as they seem to be very similar problems.

 

Thank you!

[Cougar]

I seem to recall previous posts on this sort of thing. Other folks reporting this same kind of trouble found out they had a over sensitive knock sensor that was causing the trouble. This may or may not be your trouble but something to keep in mind if nothing else seems to correct the problem.

[mcmillon]

Heys Guys, Im new to this board but have owned 5 Subarus, and this misfire condition popped up in the wife's Forester last summer and after 5 months, I finally resolved the misfire condition.

It started with a 301,302,303,304. I tested the coil and it tested bad on secondary resistance. Logically, I bought a new coil at the dealer assuming this would solve the misfire since I keep this car well tuned up. I replaced the upstream o2 sensor,check the plugs, plug wires, injectors etc.

No, this misfire continues at random intervals.

After we move here to SLC, I finally get tired of hearing the wife complain, I take it to the dealer(big mistake) the little kid tells me its the coil pack. I tell him that coil pack on the car is less than a month old so it cant be.

I let him install the new coil pack, and two days later I'm back at the dealer with the check engine light(301,302). The dealer says that they will look at it again, nope I swap the coil pack in front of the service manager and tell him to give me my money back since they didnt solve a thing.

They give me my money back and the car runs fine for three months.

 

Okay, so one morning in the cold of winter, the check engine light comes on, and so for the millionth time I hook up the code reader and get the same 300 series codes, but this time while the car is running, I check the plastic connector that plugs into the coil pack, and while its snapped in correctly, the contacts are loose.

I drive it to a small import shop and $25 later the problem is fixed. They tightned the connectors and 5k miles later and no check engine light. I don't know if this helps but it was a very frustrating issue that I am very glad is finally resolved

Be McMIllon

[Cougar]

That is a good thing to know. Thanks Mcmillon.