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Old 03-06-2012, 11:25 AM   #1
belacane
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Question intermittent rough idle, then stalls - P0303 code

Hi all,

...looked around on the forum, but did not find an answer to my question, so I'm asking here.

The Car:
-'02 WRX wagon (td04 turbo) no mods
-idles at about 600rpm


The Issue / Symptoms:
- intermittent rough idle that changes rapidly between 500 and 1200rpm (when stopped at a light for example)
- about 1/5 times, the car will stall with this rough idle and require a few restarts
- poorer than usual milage per gallon (don't know if it's related)
- gave me a P0303 code (cyl. 3 misfire)


I have not yet done any compression or leak down tests, but plan to when I get access to tools to do so.

Otherwise performance is fine. It has never stalled/quit on me while moving. It only stalls when I'm idling at a stop.



What I'm looking for:

I'm posting this hoping that someone might have some hints on what to check out from their own experience, but please, if you have nothing nice or helpful to say, don't waste your energy posting a response.

Thanks in advance!
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Last edited by belacane; 03-06-2012 at 11:27 AM. Reason: fixed typo
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Old 03-06-2012, 11:31 AM   #2
mt1101
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From numerous searches on this topic do the compression and leak test then come back with results.
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Old 03-06-2012, 11:34 AM   #3
mt1101
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Just pray it's just the coils or plugs
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Old 03-06-2012, 12:17 PM   #4
jerbull88
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Try cleaning your maf.
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Old 03-06-2012, 03:22 PM   #5
WRXSD
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Clean you MAF with MAF cleaner, and clean your IACV with gasoline. This may cure your idle hunting issues. Sometimes the IACV can be beyond fixing and require a new one however.
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Old 03-14-2012, 01:11 PM   #6
belacane
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Thanks much guys. Gonna get this done.
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Old 03-14-2012, 01:13 PM   #7
belacane
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Quote:
Originally Posted by mt1101 View Post
Just pray it's just the coils or plugs

why pray?
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Old 03-14-2012, 01:35 PM   #8
mt1101
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Bc it could be a lot worse. Definitely do what others have recommended first but for me the compression test saved a bunch of money and time...plus its easy. Good luck!
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Old 03-16-2012, 10:38 PM   #9
belacane
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well, before I even got to doing the compression test, I started poking around today, and found that the hose to the turbo was coming right off.

It's back in place, and we'll see if that fixes my problem!

I'll keep updated.
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Old 03-17-2012, 12:42 PM   #10
bigbadbronxy2k5
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Default Code 0303

I got this code on a NA 06 2.5 and unplugging the MAF and cleaning it with MAF safe cleaner from CRC cleared it up.
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Old 03-19-2012, 04:12 PM   #11
belacane
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Quote:
Originally Posted by bigbadbronxy2k5 View Post
I got this code on a NA 06 2.5 and unplugging the MAF and cleaning it with MAF safe cleaner from CRC cleared it up.
I just replaced the MAF just a few months ago....hmmm.
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Old 04-21-2012, 11:19 PM   #12
belacane
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been away for a little while, but here's an update.

compression test results:

cyl 3 - 160 (dry) 180 (wet)
cyl 1 - 160 (dry) 175 (wet)
cyl 2 - 160 (dry) 170 (wet)
cyl 4 - 160 (dry) 175 (wet)

Spark plug from cyl 3 has oil on the threads.

any thoughts?
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Old 04-22-2012, 10:29 PM   #13
nasiocanuck
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i had the same problem a few weeks ago, bad spark plug wire. coilpack possibly aswell?
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Old 04-23-2012, 12:02 AM   #14
sol_tegra
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swap coils 1 and 3 and see if the mil comes on in cylinder 1 if so then its a coil.
the oil in cyl 3 could be from leaking valve cover plug seal.
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Old 05-06-2012, 12:14 AM   #15
belacane
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Quote:
Originally Posted by nasiocanuck View Post
i had the same problem a few weeks ago, bad spark plug wire. coilpack possibly aswell?

are you saying that replacing the above fixed your problem?
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Old 06-27-2012, 09:54 AM   #16
archangelf16
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Bump. I'm having this same issue on my 06. What ended up fixing the problem? Did cleaning the MAF do it?
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Old 06-27-2012, 01:12 PM   #17
iamcgr
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Check your ground wires.

I had a similar issue after having my clutch and timing belt replaced. The shop suggested my spark plugs needed to be replaced. While doing plugs, I noticed my ground wire was loose at the battery terminal. I tightened it and the symptoms went away. While it may not cure your issue, it's worth checking. Good Luck!
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Old 06-27-2012, 03:25 PM   #18
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What color are the plugs. is that #3 plug a different color?
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Old 06-27-2012, 06:32 PM   #19
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Quote:
Originally Posted by belacane View Post
been away for a little while, but here's an update.

compression test results:

cyl 3 - 160 (dry) 180 (wet)
cyl 1 - 160 (dry) 175 (wet)
cyl 2 - 160 (dry) 170 (wet)
cyl 4 - 160 (dry) 175 (wet)

Spark plug from cyl 3 has oil on the threads.

any thoughts?

run some chevron techron injector cleaner or the lucas injector cleaner through it and replace the front o2 sensor if it is more than 5 years old

and that coilpack may be bad and you may wanna change the cam cover gaskets and the sparkplug tube seals
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Old 06-27-2012, 10:14 PM   #20
dollar5th
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why doesnt any post the fix to their issues?
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Old 07-01-2012, 06:07 PM   #21
jgrove15
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I am having a similar issue. 04 Wrx with:

20g Bosch turbo
Invidia up pipe, downpipe and q300 catback

Car was idling very low and stalling wgen i would come to a stop. Cleaned air filter, MAF sensor IACV, visual check for leaks. Now car is idling what seems to be normal but when I stop at a light it idles around 1800 to 2000. If I rev it the idle drops back to normal between 500 and 750.

Also, I have a AEM wideband gauge that has recently stop reading. It is not reading at idle and when it does have a reading while driving it is all over the place. It runs up to 18 and then doesn't read.

Any advice or suggestions would be great.
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Old 07-01-2012, 06:57 PM   #22
Uncle Scotty
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most rough idle issues that are not a dead/low cylinder are vac leak issues.....that means between the throttle plate and the heads
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Old 07-01-2012, 06:57 PM   #23
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Quote:
Originally Posted by jgrove15 View Post
I am having a similar issue. 04 Wrx with:

20g Bosch turbo
Invidia up pipe, downpipe and q300 catback

Car was idling very low and stalling wgen i would come to a stop. Cleaned air filter, MAF sensor IACV, visual check for leaks. Now car is idling what seems to be normal but when I stop at a light it idles around 1800 to 2000. If I rev it the idle drops back to normal between 500 and 750.

Also, I have a AEM wideband gauge that has recently stop reading. It is not reading at idle and when it does have a reading while driving it is all over the place. It runs up to 18 and then doesn't read.

Any advice or suggestions would be great.
you sound like your o2 sensors are dead
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Old 07-01-2012, 07:13 PM   #24
jgrove15
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Is there an easy way to check the o2 sensor or should I just replace? Are you talking about the stock 02 sensor or the wideband sensor or both.
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Old 07-01-2012, 07:23 PM   #25
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Do you think it could be the stock o2 sensor or the wideband sensor or both? Is there a way to check if they are bad or just replace?
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