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Discussion Starter · #1 ·
I recently bought a 2012 Subaru Wrx and have had it for about a month now with just under 100k on the odometer. I bought it from a Subaru dealer and they had said nothing of a CEL coming on or any issue. I got my first code within the first week of owning it and driving it around. It popped up and was just a cylinder 3 misfire, but I did not notice a lack in power or a stutter of any kind when the car threw the code. I just simply turned it on and let it warm up and idle and it popped up. I cleared the code bc I thought it just read something funny upon the start-up since it was a cold start-up and it didn't throw a code for another week or so and then it was again cylinder 3 so I did the same and I filled up at a gas station with 92 fuel and always put premium in my tank upon fillup. I get another code and it says misfire on cylinder 1 and 3 so I pulled the plugs out and just did all the plugs with NGK Iridium plugs, just before I did plugs I got that code for cylinder 1 and 3. After I cleared it my car would not idle, it would go all the way down to just about stalling out or stall out when you would start it up, I then used the method to recalibrate the throttle body which is just letting the battery sit, disconnected and turning the car on and off for 10 or 5 minutes without touching anything and just letting it idle and that fixed the idle situation. I have talked to a few other owners and whenever they get a code and clear it, they have no issue upon starting up afterward so idk what that means. But, I changed plugs, recalibrated the throttle body, saw on another forum that the wiring harness can be bad around the connector for the engine by the turbo and I wiggled that and nothing seemed to happen, no shaky idle or misfire. Then I was driving around yesterday after recently changing plugs and having no codes, I got another CEL and I checked it and it says a misfire on cylinder 1,2, and 3 and I notice no loss in power, no hesitation while I go up in rpm, it does dip in rpm while idling sometimes but then sits at about 700 to 800 rpm 95% of the time and all plugs came out dry and had nothing weird happening, also cleaned MAF and didn't help, the code came back within a day or two. Does anyone have any suggestions that I could check for besides dropping it off at a shop or throwing parts at it?
 

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Could be dozens of things, check the misfire thread
 

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It could be blown head gaskets, bad ECU, bad tune, haphazardly modified vehicle, boost leaks, intake leaks, failed valves, failed pistons, failing fuel pump, bad knock sensor, exhaust leak, wastegate problems, dead engine, among many other things cause exactly the problems you've mentioned.

I'll refer you back to the misfire thread. We can sit here and wax poetic all day but you've got to be the one eliminating possible issues by diagnosing, or we can just go round and round.
 

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I recently bought a 2012 Subaru Wrx and have had it for about a month now with just under 100k on the odometer. I bought it from a Subaru dealer and they had said nothing of a CEL coming on or any issue. I got my first code within the first week of owning it and driving it around. It popped up and was just a cylinder 3 misfire, but I did not notice a lack in power or a stutter of any kind when the car threw the code. I just simply turned it on and let it warm up and idle and it popped up. I cleared the code bc I thought it just read something funny upon the start-up since it was a cold start-up and it didn't throw a code for another week or so and then it was again cylinder 3 so I did the same and I filled up at a gas station with 92 fuel and always put premium in my tank upon fillup. I get another code and it says misfire on cylinder 1 and 3 so I pulled the plugs out and just did all the plugs with NGK Iridium plugs, just before I did plugs I got that code for cylinder 1 and 3. After I cleared it my car would not idle, it would go all the way down to just about stalling out or stall out when you would start it up, I then used the method to recalibrate the throttle body which is just letting the battery sit, disconnected and turning the car on and off for 10 or 5 minutes without touching anything and just letting it idle and that fixed the idle situation. I have talked to a few other owners and whenever they get a code and clear it, they have no issue upon starting up afterward so idk what that means. But, I changed plugs, recalibrated the throttle body, saw on another forum that the wiring harness can be bad around the connector for the engine by the turbo and I wiggled that and nothing seemed to happen, no shaky idle or misfire. Then I was driving around yesterday after recently changing plugs and having no codes, I got another CEL and I checked it and it says a misfire on cylinder 1,2, and 3 and I notice no loss in power, no hesitation while I go up in rpm, it does dip in rpm while idling sometimes but then sits at about 700 to 800 rpm 95% of the time and all plugs came out dry and had nothing weird happening, also cleaned MAF and didn't help, the code came back within a day or two. Does anyone have any suggestions that I could check for besides dropping it off at a shop or throwing parts at it?
Was your timing belt recently done? Could be a bad tensioner and belt skipped a few teeth, or worse case scenario could be a cracked valve or cracked piston. Check for blowby, do a leak down test (compression test is not the best but you can try it out.)

In my experience when i had a burned exhaust valve it was idling rough, which does not seem to be your case.

Hope you are able to fix it soon.
 

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Was your timing belt recently done? Could be a bad tensioner and belt skipped a few teeth, or worse case scenario could be a cracked valve or cracked piston. Check for blowby, do a leak down test (compression test is not the best but you can try it out.)

In my experience when i had a burned exhaust valve it was idling rough, which does not seem to be your case.

Hope you are able to fix it soon.
If it skipped a few teeth it would run like garbage. It doesn't so we can easily rule that out.
 

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If it skipped a few teeth it would run like garbage. It doesn't so we can easily rule that out.
If its only one tooth per cam you would not notice it....... once a while back i did the timing belt in my car and i was getting a P0301 P0302 P0303 and P0304. Car was ruuning ok, changed plugs, changed coils, checked the grounds, checked the wiring, turned out it was the tensioner.
 

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Discussion Starter · #8 ·
Update- I ran injector cleaner through it and ran it through one tank of gas and also changed where I got gas and ended up cleaning that crank positioning sensor and the idle is perfect now and it has been about 500 miles of driving and no codes or idle issues. I am assuming it was bad fuel or an injector was just dirty. the sensor I cleaned had a little bit of build-up but nothing that was alarming or would have caused it to throw any miscellaneous codes.
 

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Discussion Starter · #9 ·
I just got the same check engine light back after driving it maybe 1,000 miles, could it be my injectors are slowly going bad and this is them showing their signs? It happens at idle every misfire code I get and it is Freeze frame on the OBDII scanner I have. it has been at about 850 rpm to about 750 and every time I get it, it is usually upon a cold start-up and after about 4 minutes of running. I have no idea how to change the injectors or check them but I have heard they are annoying to do because of the brackets of death. anyone have any ways to check them?
 

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I just got the same check engine light back after driving it maybe 1,000 miles, could it be my injectors are slowly going bad and this is them showing their signs? It happens at idle every misfire code I get and it is Freeze frame on the OBDII scanner I have. it has been at about 850 rpm to about 750 and every time I get it, it is usually upon a cold start-up and after about 4 minutes of running. I have no idea how to change the injectors or check them but I have heard they are annoying to do because of the brackets of death. anyone have any ways to check them?
Grab a long screw driver, place the metal tip of the screw driver on the injector, put your ear to the handle of the screw driver. If you hear clicking then injectors are good.

What are the codes you are getting?

A bad or going bad cat converter can trigger P0301, P0302, P0303, P0303.
A bad or going bad cat converter can trigger codes related to running too lean.
A bad or going bad cat converter can trigger code for a bad O2 sensor (bank 1)

Post the codes you got to better assist you
 

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Discussion Starter · #12 ·
Grab a long screw driver, place the metal tip of the screw driver on the injector, put your ear to the handle of the screw driver. If you hear clicking then injectors are good.

What are the codes you are getting?

A bad or going bad cat converter can trigger P0301, P0302, P0303, P0303.
A bad or going bad cat converter can trigger codes related to running too lean.
A bad or going bad cat converter can trigger code for a bad O2 sensor (bank 1)

Post the codes you got to better assist you
The codes I am getting are P0303 AND P0301 which is a misfire for cylinder 1 and 3, it has never been cylinder 4 and I still feel no loss in power, is there a way to test the cat? Or is it just a look at it from the inside and see if it is blown or not
 

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The codes I am getting are P0303 AND P0301 which is a misfire for cylinder 1 and 3, it has never been cylinder 4 and I still feel no loss in power, is there a way to test the cat? Or is it just a look at it from the inside and see if it is blown or not
check for ground cable on that side.
 

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The codes I am getting are P0303 AND P0301 which is a misfire for cylinder 1 and 3, it has never been cylinder 4 and I still feel no loss in power, is there a way to test the cat? Or is it just a look at it from the inside and see if it is blown or not
From left to right, see where the yellow line begins, thats your ground. make sure its tight.

also , reset the computer and see if codes come back.
 

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Discussion Starter · #16 ·
From left to right, see where the yellow line begins, thats your ground. make sure its tight.

also , reset the computer and see if codes come back.
Would it be the same for a 2012 subaru wrx? That looks to be from an earlier wrx
 

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Would it be the same for a 2012 subaru wrx? That looks to be from an earlier wrx
Same for all WRX. Engine layout is the same.

Based on your codes im inclined to think of a bad ground.

If your ground cable on the intake manifold its goo, then proceed to check for a ground that goes to the firewall from engine/gear box.

Hope that helps
 

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Discussion Starter · #19 ·
I went to the dealership for the issue and they did a leakdown, checked plugs and ran their diag and they came up with no issues, it all checked out, any ideas? They said next step is to do a valve clearance check but I don't have 1,000$ to do so.
 

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I went to the dealership for the issue and they did a leakdown, checked plugs and ran their diag and they came up with no issues, it all checked out, any ideas? They said next step is to do a valve clearance check but I don't have 1,000$ to do so.
hhhmmmm..... did they check the timing...... if it runs a bit rough probably belt is loose or the tensioner is shot and cams jump a tooth.......
 
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