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Thread: Two NTK WBO2 Sensors - Output Differences

  1. #1

    Default Two NTK WBO2 Sensors - Output Differences

    Hello. I'm getting some readings that are about 1.0 AFR difference between NTKs in my datalog. I have one in each collector. When I key on my ignition, my one sensor shows 28.0 and the other shows 26.0, is this an indication that one of my sensors is not reading correctly any longer? Or is this normal? Thanks in advance. Eric

  2. #2
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    At key-on (initializing) and heating, the WBO2 sensor "LED" status indicator is yellow.
    Then there shouldn't be any "LED" status indicator at all (especially when engine is running).
    The WBO2 sensor heating cycle will time-out (key-on/engine-off) if the engine isn't started.
    When the WBO2 sensor heating cycle times-out (key-on/engine-off), it will display "init".
    http://documents.holley.com/techlibr...__statuses.pdf (Sensor Diagnostics & Statuses)
    http://forums.holley.com/showthread....8295#post48295 (Ensure battery is fully charged!)
    Key-on/engine-off & cold, the NTK WBO2 sensor displays about 29:1 AFR. The Bosch WBO2 sensor displays about 35:1 AFR.
    After turning the engine off, exhaust gases need to dissipate before seeing these full lean AFRs (key-on/engine-off & cold).

    https://forums.holley.com/showthread...5480#post45480 (Potential Causes Of L & R Bank AFR Differences)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3

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    Hi Danny. When I key-on while the engine is cold, one sensor reads 26.8 and the other reads 28.0. Does this mean one of my sensors is bad? I attached a picture for reference. If it's bad, I guess there is nothing I can do but order a new one? Thanks, Eric
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  4. #4
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    No, the two engine banks will never display the exact same AFR (key-on/engine-off). It's nearly impossible for the oxygen content to be the exact same. What you're seeing is completely normal.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #5
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    The readings you're seeing are high oxygen (lean condition), since the engine is not running. Depends on how long the engine has been stopped, but will starting climbing towards lean after shutdown. All completely acceptable. Swap the WBO2 sensors to see if the readings swap. Gary
    Regards, Gary

  6. #6

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    Good idea I'll try swapping them to see if the readings stay the same or if they differ. I did this test on a cold engine and I forgot to mention that this is on a open header application so there's only six inches from the opening to the WBO2 sensor. I can see if this was a closed exhaust, but since it's open, I'd think they would both read the leanest condition. I'll report back. Eric

  7. #7
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    The oxygen sensing element is inside the WBO2 sensor probe.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  8. #8

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    Quote Originally Posted by emueller View Post
    ...this is on a open header application so there's only six inches from the opening to the WBO2 sensor.
    AFAIK minimum pipe length behind a wideband is 12". With only 6" you will not get reliable readings, as air will be sucked in between exhaust pulses.

  9. #9

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    Quote Originally Posted by zwede View Post
    AFAIK minimum pipe length behind a wideband is 12". With only 6" you will not get reliable readings, as air will be sucked in between exhaust pulses.
    I'm helping him tune his car and it does seem like it gets accurate around 5800, which is fine for a track only car. We've done some cylinder trimming and the datalogs look much better. Up next is a side to side swap and see what happens. My hope is nothing will change. Even if it does, the tune is conservative enough that it won't matter. He will do some plug reading too (base of porcelain).
    Last edited by allan5oh; 11-03-2019 at 11:24 PM.

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