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Discussion Starter #1
I'm trying to get down the root of the problem. This is for a 2005 Subaru WRX with 93k miles on it.

I haven't driven my car many miles in the past months. Probably 1,000 miles over 7 months. I try to take it out once a week for about 15-20 mile drive.

I recently starting having problems. I first noticed that my car would shuttered only under heavy acceleration. My CEL would flash a few times and go off. I first checked the code. It had a misfire on cylinder one. I figured my injectors were getting plugged up since my car sits a lot. I put fuel injector cleaner through. I also cleaned out the purge valve. My code cleared for cylinder one. I still have the acceleration problem. This only happens under heavy acceleration, my car shutters once it moves up into the higher RPMs. If I gradually accelerate, no issues. Now, I'm having a misfire on cylinder 3.

My car is completely stock. No replacement parts besides general maintenance items.
 

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Discussion Starter #2
Just to add. I also swapped out the coil packs and spark plugs to see if that made a difference. My codes didn't change based on swapping parts around.
 

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And do you put fresh gas every month or so?
 

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Discussion Starter #4 (Edited)
I do, I never fill up the tank all the way in order to make sure I can put fresh fuel in every once in awhile. I run it down to about 1/8 of a tank, then fill it back up to a 1/4.
 

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Check the fuel filters and injectors. Have you done your timing belt/pullies/water pump/thermostat yet?
 

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Discussion Starter #6
Alright, thanks I'll take a look at that. I haven't done any of that maintenance yet. I was reading the manual saying that the timing belt is at 120k.

I haven't done anything to the water pump or thermostat, just full radiator flushes every 30k. I'm not having any overheating problems.
 

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When you swapped the parts around, did the misfire move? Are you boosting at all, or is the cut out that bad? Only other thing I would recommend to check is your vac lines. Maybe one is dry rotted from sitting?

Timing belt is @ 90k btw.
 

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Discussion Starter #8
The misfiring didn't move to another cylinder. The boost cuts in and out. So it'll kick on for a second, then the car would shutter. It would kick back on, do this about 6-7 times up to the redline. It only happens when I have really push it. If I gradually accelerate up to redline, its smooth and boosting.

I checked out all the lines I could get to. No cracking of any sort.
 

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Almost sounds like a bad MAF....I would check that next if your fuel checks out okay.
 

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Discussion Starter #10
Wouldn't the bad MAF trigger a code and cause the car to idle rough?

I took the car out of a drive today. The car only shutters when its boosting. At lower RPMs with the pedal to the floor, it accelerates smoothly. I will begin to hear the turbo start spooling up. Get the burst of power, then it shutters. I also hear what it almost sounds like, air escaping. I'm starting to wonder if I have a bad air by-pass valve. Could it pre-maturely failing?
 

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Check for boost leaks. under the TMIC first.
 

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my car is doing the exact same thing. i just changed plugs. the old ones were shot and it seemed to help a little. doesnt do it much in first gear but 2-5th is horrible. when you find out what your issue is, please let me know! i just bought the car yesterday and gotta get this figured out.
 

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I'm sure I will get a little bit of hate for this but... I was having the same problem on my RX8 like a week ago right after I filled up the tank. before I filled up I was having a rough idle problem, but after I got gas the car completly died on me while driving down the highway, and would not restart... to get to the point after trying a few things myself I ended up taking it to the shop. They ended up replacing the plugs and wires, the coils, and the fuel pump (because they broke it). they also came to the conclusion that the gas in the tank was contaminated, so they drained it (hints the broken pump) and filled it back up. The shop told me that it was a combination of all of the problems together making the car act like it did. when I got it back it ran like a CHAMP (or as well as expected for an RX8) haha. When you take the car to get gas are you going to the same place every time? maybe their gas is slightly contaminated? maybe so octane booster would help?

And just to clarify to hopefully reduce the amount of flame I will receive I have a 2013 wrx on order, currently waiting for it to get to the dealer, I am not just randomly a member of a subie forum.
 

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it sounds like we have the same problem, but my car isnt throwing a code. i replaced plugs, swapped my bov with a stock bypass valve, checked the y pipe under the tmic and all charge pipes for leaks/cracks and couldnt find anything.
 

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there is no distributor. its coil on plug. i disconnected my electronic boost controller and now the car runs and boosts fine (14psi) i'm assuming i just have a bad tune.
 

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Sounds to me like the car is running crazy lean. Fuel Pressure Regulator? I've only had my old Prelude run like that when it was getting tuned for Nitrous and we were about 10% down on the fuel trim from where we should have been. I toasted the spark plugs and actually melted the electrodes off of them. I'd look at the FPR first, and run fuel injector cleaner for sure, as you're likely mixing up crap out of the bottom of the tank every time you fill up and not getting it far from the entrance to the line. That's my $.02.
 

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Hey, I, new to the forum I recently bought a 2010 WRX. It has 33xxx miles with no apparent mods. I bought it from a subie dealer in my area that took it in on trade. It ran beautifully for the first 2 weeks, then I had the same exact issue everyone here is describing. It threw 2 codes the dealer attributed to a loose connection. They cleaned the maf and replaced the plugs and said I was fine. As it threw a misfire code ~1000 feet from the dealer when they said they "fixed" it they kept it for 2 days. The final diagnosis was bad gas, a vapor test gave a result of 6psi of the gas. I've cleared the bad gas, ran a few bottles of fuel system cleaner through and having the same issue. Up to about 9 psi of boost its fine, after that the car shudders and dumps boost. If I keep accelerating it will throw a misfire code in cylinder 1.
Sorry for the long post, but I really want to get this fixed, the car was amazing when I first bought it but now I'm thoroughly disappointed with it. Any help would be much appreciated!
 
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