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Thread: Idle afr question using ngk afx wb...

  1. #1
    Tuner in Training
    Join Date
    Jan 2012
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    33

    Idle afr question using ngk afx wb...

    I have an cammed g8 and have just started trying to use a wb. When I start the car, and it is warmed up, I am getting readings between low 13 to almost 16. I am wondering if this is normal? I assumed it would be very close to 14.7. I did not get a chance to drive around as it was snowing. My other question is regarding o2 sensors. I have just hit 36k miles. I am wondering if maybe my stock o2's could be wearing out and not doing their job. Do these wear out over time, or do they just work/fail and there is no in between? Thanks for any input, and dealing with a new tuner.
    2009 Pontiac G8. Camaro 3.45's, 222/230 114+2 .59x/.60x, VCM intake, ported intake/heads/tb, 1 3/4 Kooks lt's, Solo hf cats and cat back, udp. 12.2 @ 117 2.05 60 ft.

  2. #2
    Tuner in Training
    Join Date
    May 2012
    Posts
    10
    It is normal for afr readings to go up and down more noticeably at idle. you would care about the average value which is (13+16)/2= 14.5afr. the farther your wideband is from the manifolds the more stable reading you will get.

  3. #3
    Senior Tuner
    Join Date
    Sep 2008
    Posts
    1,668
    The cam causes the idle AFR to be sloppy (up/down) more so than stock...36K isn't really bad for the narrowbands, but they don't just work/not work...it's been my experience that they start to respond slower over time, and they also tend to show leaner than the engine really is (thus prompting the PCM to add fuel) as they age...if you're concerned about it, a new pair of O2 sensors is cheap...and if you notice the fuel trims stay the same before/after then keep the old sensors as spares in the event that you do have a bad failure (sometimes they do just plain fail...not often though).
    2010 Camaro SS M6. Stock Bottom End, Heads/Cam/Intake/Headers/Exhaust.
    2005 Silverado RCSB. Forged 370 LQ9/Borg-Forced Inductions T6 S484/Jake's Stage 4 4L80E with D3 Brake/4WD.
    2023 Durango Hellcat