Subaru Intermittent Misfire - P0300
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Date: 2020-08-05
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Comments and reviews: 10
RC
I had a 1982 Mercury Lynx, brand new about 500 miles and the coil was leaking oil. I took it to the garage under warrenty and the service manager told me that because it was still working, they might not be able to cover it. I blew up at him and told him so its NORMAL to leak and they ALL are supposed to leak? I told him I wanted to see his manager. What an IDIOT! The manager looked at him and said REALLY? JUST REPLACE IT! I had it out with that service manager again when the exhaust fell off a week later. It was defective. At first he started his crap and I said Really? Just like the Manager said for the coil. They replaced it. A month later I got a RECALL on it for the exhaust being defective. That was the same model that was recalled for bad headbolts. Mine never developed an issue so I never took it in. Apparently, the headbolts were supposed to stretch but didnt, so many Escorts were developing blown head gaskets or the head bolt were snapping off in the head. I put about 200k on that little car before trading it. I owned two other Escorts after that. I actually had 280k on our last Escort. I took it in to the dealer and he said it had hardly any compression left and was blown away we had put that many miles on an Escort. I had changed the timing belt twice in its life time, did countless brake jobs and many other things but that kept that Escort running up till the end of its serviceable life. The mechanic was impressed that looked at it. Came out to tell me he had never seen an Escort with that many miles and well maintained. Hey, I will take those compliments all day long.
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I had a 1982 Mercury Lynx, brand new about 500 miles and the coil was leaking oil. I took it to the garage under warrenty and the service manager told me that because it was still working, they might not be able to cover it. I blew up at him and told him so its NORMAL to leak and they ALL are supposed to leak? I told him I wanted to see his manager. What an IDIOT! The manager looked at him and said REALLY? JUST REPLACE IT! I had it out with that service manager again when the exhaust fell off a week later. It was defective. At first he started his crap and I said Really? Just like the Manager said for the coil. They replaced it. A month later I got a RECALL on it for the exhaust being defective. That was the same model that was recalled for bad headbolts. Mine never developed an issue so I never took it in. Apparently, the headbolts were supposed to stretch but didnt, so many Escorts were developing blown head gaskets or the head bolt were snapping off in the head. I put about 200k on that little car before trading it. I owned two other Escorts after that. I actually had 280k on our last Escort. I took it in to the dealer and he said it had hardly any compression left and was blown away we had put that many miles on an Escort. I had changed the timing belt twice in its life time, did countless brake jobs and many other things but that kept that Escort running up till the end of its serviceable life. The mechanic was impressed that looked at it. Came out to tell me he had never seen an Escort with that many miles and well maintained. Hey, I will take those compliments all day long.
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Squirrel
I hate ignition/electrical issues. Hade a problem once with my 98 Dodge Dakota V6. I had put on an aftermarket ignition box, an Accel coil, plugs and everything else that would go with it. As I would be going down the road it would start to misfire and die. No matter what the garage did they could never get it to do it. And then one day as I was backing it out of their garage it did it as it was just sitting there. Long story short it turns out that there needs to be one more part added to the ignition system to keep that vehicle from doing that.
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I hate ignition/electrical issues. Hade a problem once with my 98 Dodge Dakota V6. I had put on an aftermarket ignition box, an Accel coil, plugs and everything else that would go with it. As I would be going down the road it would start to misfire and die. No matter what the garage did they could never get it to do it. And then one day as I was backing it out of their garage it did it as it was just sitting there. Long story short it turns out that there needs to be one more part added to the ignition system to keep that vehicle from doing that.
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juicer52
P0303 on my 08 Outback. Happens after car has been sitting in a very damp garage. Car bucks until it warms up and then some. Pulled #3 wire and the spark plug tube had moisture on it. Dried it off and let the plug well dry out before reassembling and it runs fine now. Would you use dielectric grease (or some other substance) along the top neck of the tube where it seats into and seals up against the engine to prevent moisture making its way down the tube?
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P0303 on my 08 Outback. Happens after car has been sitting in a very damp garage. Car bucks until it warms up and then some. Pulled #3 wire and the spark plug tube had moisture on it. Dried it off and let the plug well dry out before reassembling and it runs fine now. Would you use dielectric grease (or some other substance) along the top neck of the tube where it seats into and seals up against the engine to prevent moisture making its way down the tube?
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rmblwgn
Gosh darnit I just Did a Vf39 turbo swap onto my 2005 ej205 w/pink injectors and sti intercooler and now I have p303 misfire. Car idles rough and has no power, turbo will barely spool before 4k rpm. I replaced turbo inlet hose as oem one sucks and it was falling apart so I thought that would solve problem(massive vacuum leak) but same problem persists. Anyone have any ideas. Problem was not present before swap.
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Gosh darnit I just Did a Vf39 turbo swap onto my 2005 ej205 w/pink injectors and sti intercooler and now I have p303 misfire. Car idles rough and has no power, turbo will barely spool before 4k rpm. I replaced turbo inlet hose as oem one sucks and it was falling apart so I thought that would solve problem(massive vacuum leak) but same problem persists. Anyone have any ideas. Problem was not present before swap.
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Medic
Unfortunately I don't have a scope or know anyone who does. but I do have a complete parts car. so I have no choice but to play swapper if all the DVOM readings check out and I can't look at PRI/SEC waveforms for clues.
Some year I might be able to afford an old school Vantage or VantagePro with my depressing medic paycheck. Sad that a people medic gets 9 bucks an hour and car medic gets 70. :-0
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Unfortunately I don't have a scope or know anyone who does. but I do have a complete parts car. so I have no choice but to play swapper if all the DVOM readings check out and I can't look at PRI/SEC waveforms for clues.
Some year I might be able to afford an old school Vantage or VantagePro with my depressing medic paycheck. Sad that a people medic gets 9 bucks an hour and car medic gets 70. :-0
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Natedoc808
I finally tracked down my misfire mishaps! Two problems: poor connection in ECM to manifold harness connector which cleaned up with contact cleaning and extra ooomph plugging it in. after that the Cyl 3 misfire continued: Ohm-Ed it out and found open ECM wife in the manifold side of the harness. Now to isolate to wire vs plugs. Id have loved to turn you loose on my 02 WRX wagon on this one.
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I finally tracked down my misfire mishaps! Two problems: poor connection in ECM to manifold harness connector which cleaned up with contact cleaning and extra ooomph plugging it in. after that the Cyl 3 misfire continued: Ohm-Ed it out and found open ECM wife in the manifold side of the harness. Now to isolate to wire vs plugs. Id have loved to turn you loose on my 02 WRX wagon on this one.
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Michael
Just replaced the ignition coil on my 08 Forester, had rough running and code P0302. Coil looked a little crusty on wire 2 post, in fact the wire broke off. I dont have a fancy scanner so I took a chance and replaced it (and plug wire) with parts from the junkyard. Figured I could buy 20 coils used for the price of one new. Anyway, took the car out for a toot, problem solved. Thanks Eric!
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Just replaced the ignition coil on my 08 Forester, had rough running and code P0302. Coil looked a little crusty on wire 2 post, in fact the wire broke off. I dont have a fancy scanner so I took a chance and replaced it (and plug wire) with parts from the junkyard. Figured I could buy 20 coils used for the price of one new. Anyway, took the car out for a toot, problem solved. Thanks Eric!
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chrisdash83
Hey Eric, I've got a 2005 Toyota Prius II with 150k miles, it runs fine and no MIL, but it has a P0301 (sporadic. So the issue is limited to cylinder 1. Am I right to assume its most likely spark plug 1, ignition coil 1, bad wiring for cylinder 1 ignition, or a worn out (not compression) cylinder 1? Vacuum leaks, bad MAF, etc should result in more randomly spread misfires, right?
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Hey Eric, I've got a 2005 Toyota Prius II with 150k miles, it runs fine and no MIL, but it has a P0301 (sporadic. So the issue is limited to cylinder 1. Am I right to assume its most likely spark plug 1, ignition coil 1, bad wiring for cylinder 1 ignition, or a worn out (not compression) cylinder 1? Vacuum leaks, bad MAF, etc should result in more randomly spread misfires, right?
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xMG
My 06 legacy gt's engine started to shake when i went to accelerate when i was on the highway i was going like 60 and i tried accelerating more and it started to shake then the CEL blinked like twice then went away and then came on later, what could this be?
Also my brother checked the coils and one of them was kinda cracked, do you think it couldve been the coil?
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My 06 legacy gt's engine started to shake when i went to accelerate when i was on the highway i was going like 60 and i tried accelerating more and it started to shake then the CEL blinked like twice then went away and then came on later, what could this be?
Also my brother checked the coils and one of them was kinda cracked, do you think it couldve been the coil?
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mark
Same thing happening with my 2002 Buick regal 3800 non supercharger. Intermittently random misfire code 0300. Very difficult to diagnosis when engine runs fine for a month then once in a while looses power then regains power within ten seconds. I just don't know how to tackle this. I would rather not wait to be stranded. Any suggestions?
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Same thing happening with my 2002 Buick regal 3800 non supercharger. Intermittently random misfire code 0300. Very difficult to diagnosis when engine runs fine for a month then once in a while looses power then regains power within ten seconds. I just don't know how to tackle this. I would rather not wait to be stranded. Any suggestions?
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