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Old 03-10-2014, 06:02 PM   #1
Strycnine
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Default O2 problems.

So my 2012 wrx has developed erratic A/F ratio in closed loop in the last 1k miles or so. Under light throttle it bounces back and forth from 11-20 A/F. I did the test by disconnecting the front O2 to confirm it was an O2 problem and itran great. Im wondering if there is a possibility it could be more than just the front O2. Could it possibly be both? Or does this confirm its just the one.

Also, my car has invidia catless exhaust with the big piping 1 pc header if that helps. Im running cobb stage 2+ Sf.
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Old 03-10-2014, 07:14 PM   #2
HinshawWRX
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How are you reading this?
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Old 03-10-2014, 07:35 PM   #3
Andrewxxcarlson
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Sure you don't have a crack in that 1 pc no name header?..
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Old 03-11-2014, 01:32 AM   #4
Strycnine
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Reading the A/F via cobb accessport. Car was surging under light throttle so I checked into it. MAF reads steady A/F bounces all over. No exhaust leaks, header is Invidia. Like I said car runs perfect with o2 unplugged. I suppose I could investigate further for cracks. Headers are wrapped though :/
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Old 03-11-2014, 01:47 AM   #5
Kirby10
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I think I am having the same issue with my 2010 STi. I had the car pro tuned at 32k and now I'm at 60k. But with light throttle I get hesitation/lite stumble on only partial steady throttle
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Old 03-11-2014, 12:30 PM   #6
Razgeiz
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Quote:
Originally Posted by Strycnine View Post
Reading the A/F via cobb accessport. Car was surging under light throttle so I checked into it. MAF reads steady A/F bounces all over. No exhaust leaks, header is Invidia. Like I said car runs perfect with o2 unplugged. I suppose I could investigate further for cracks. Headers are wrapped though :/
Well. You figured out your problem Idk why you are asking here. You unplugged your front o2 and blam it works right! Your o2 is bad switch it out and call it a day.
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Old 03-11-2014, 08:41 PM   #7
Strycnine
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K, just confirming before I go throwing money at it.
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Old 03-12-2014, 09:55 AM   #8
Razgeiz
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Quote:
Originally Posted by Strycnine View Post
K, just confirming before I go throwing money at it.
I get ya man, I should say in typical Nasioc fashion to search lol.
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Old 03-13-2014, 07:44 AM   #9
Strycnine
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Does anyone have any experience with the NGK vs the Denso o2 sensor? For
example, which one will last longer.
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Old 03-13-2014, 08:23 AM   #10
Razgeiz
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Just use the factory replacement which I believe is Denso.
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Old 03-13-2014, 11:29 AM   #11
Strycnine
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K, thanks. I decided to just get the Denso one. If it burns up after a year ohwell i guess.
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Old 03-13-2014, 11:50 AM   #12
Razgeiz
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Quote:
Originally Posted by Strycnine View Post
K, thanks. I decided to just get the Denso one. If it burns up after a year ohwell i guess.
Just make sure you reinstall the copper heat sink that was on the original one that's what will keep it from burning up. Good luck man!
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