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10-08-2008, 03:57 AM
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#1 (permalink) |
04 FXT Misfire CEL Codes PO301 PO302 PO303 PO304 and Info
I realize there are other threads out there covering the infamous misfire CEL codes (PO301, PO302, PO303, PO304) but I figured I would share my recent struggles with a PO301 of my own on my 04 FXT. Let me start by saying that I did not experience a misfire until we started having gas shortages here lately. I managed to find some 93 octane during the shortage, but it must have been toward the bottom of the gas station's tank. A couple of days later I got a PO301. I was told by the guys at Autozone that the gas stations being low has resulting in some 'crap' floating around the bottom of their tanks and getting into customers' fuel systems. Regardless, I took it on a whim. I decided to take the car, recently purchased used w/ 95k miles on it, to the local Subaru dealership. They also said they have heard of gas issues and I have heard the same from a few other people as well. I highly doubt the gas in general is the issue as I am only having one cylinder misfire. It is possible there was debris in the gas that clogged the fuel injector, but I had the fuel injectors cleaned, spark plugs replaced, and fuel filter replaced along with all other 30k mile services and a few misc things but the problem was not resolved. I thought the misfire was history and next thing I know, the day after I pick the car up from Subaru I get another PO301, then the next day another PO301. I drove the car one more day - no more codes that day. I decided I should park it and finally order a replacement coil pack as that is practically the only thing left to replace/clean/update. I installed the coil pack and got a CEL again 20 miles later. Same PO301 CEL and it has happened multiple times since. I then switched the injector with cylinder 2 in hopes that the misfire would follow. That way I would know that it was just the injector and not the head or something worse. After the switch, I got the CEL again - P0301 AGAIN! After that I was pretty stuck so I have decided I will get a compression check next and accept reality if I have a messed up head. First, I went to Pepboys and got some pour-in valve-unsticker stuff in hopes that I have a stuck exhaust valve and it would free it up. I put it in and reset the ECU. I drove 40 miles, pretty darn hard on the gas, and then filled up at the gas station and added STP fuel system cleaner stuff too. I drove another 10 miles and still no CEL yet - the longest I have gone yet. 55 miles after the pour-in stuff, I got the CEL again. I almost took it to Subaru then, but decided to give SeaFoam a shot as a last-ditch effort. The next morning I took the car to Subaru for a diagnostic, compression test, etc. They said it would take 1-1.5 hours. I waited 3+ hours. They gave the car back and said they had no idea what the problem was. I left dissatisfied but the CEL didn't come back on for 175 miles. The SeaFoam may have helped a good bit, but not a fix. I got the CEL read and cleared at AutoZone and then it came back on 20 miles later and flashed again 10 miles later. I was right back where I started. I then called Cobb and asked a few questions. I unmarried my AccessPort V2 from my STi and installed it on the FXT with Stage 1 93oct map. All the readings the Cobb AP provides looked good. A/F, Voltage, Injectors, MAF, etc all looked normal... to me at least. Went ahead and installed STi TMIC and 3" turboback w/ Stage 2 OTS AP Map - things seem fine now!
P0301 suspected to be caused by: - Bad gas/debris? - Bad spark plug? - Dirty/bad fuel injector? - Probably not fuel filter as it was the same cylinder multiple times - Probably not o2 sensor as it was the same cylinder multiple times - Stuck exhaust valve? Steps attempted so far: - Replace spark plugs - still PO301 - Clean fuel injectors - still PO301 - Replace fuel filter - still PO301 - Replace coil pack - still PO301 - Switched fuel injectors with cylinder 2 to make sure it wasn't the fuel injector - still P0301 - Valve-Medic pour-in stuff - same CEL after ~55 miles, still running a bit rough - Sea Foam used in BPV vacuum hose, fuel filler, and oil filler - no CEL after 150+ miles, but still running roughly - Oil changed 2 days after SeaFoam was used - Wiring rechecked - Cobb AP Stage 1 93oct Map flashed - no CEL - Cobb AP Stage 2 93oct Map flashed - no CEL PLEASE HELP!!! ANY NEW IDEAS OR SUGGESTIONS APPRECIATED!!! Video of Sea Foam in action: The squeaking is my A/C belt. Subaru replaced all my belts and the A/C won't stop squeaking now. I have tightened it and all. I am going to just have to replace with some better belts and crank pulley I guess hehehe Valve Medic and Sea Foam seem to have been the biggest, and cheapest, help after all of this! $3.99 or so for Valve Medic and $8 or so for Sea Foam at Pep Boys might have been the solution, even after lots spent at Subaru and over $100 in suspected parts in need of replacement which did not make any immediate difference.   Last edited by sagelwwa : 10-28-2008 at 05:36 PM. |
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10-08-2008, 04:37 AM
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#2 (permalink) |
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Contributing Member
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I would say there is a very good chance the 93 you thought you were buying may have been a lower octane gas.
I have a sneaking suspicion when the gas stations do get gas (after being totally dry), it always seems to be 93. All the other pumps will have there platic bags over them, but miraculously they all of the sudden have the expensive stuff (after being COMPLETELY out of gas for two weeks). I have seen this at several stations around me. I think the stations are hurting so bad for money they are duping the public by selling the junk out of the 93 pump. Highly illegal, but who is out there checking to see if it is legit? Nobody.
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05 OB XT with a little gravy, 04 F XT with all the trimmings. |
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10-09-2008, 02:26 PM
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#5 (permalink) |
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President of MarkyD fan club
Contributing Member
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Have you considered buying some octane boost? If it is due to low octane that may help. I do find it very suspicious that the CELs didn't occur until the gas shortage. I get a misfire code every once in a long while but it's most likely due to my lightened flywheel.
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06XT MT CGM Blouch TD05-18g 8cm equipped |
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10-10-2008, 05:28 PM
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#7 (permalink) | |
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Linear Mode
