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Thread: WBO2 sensor not reading correctly.

  1. #1

    Default WBO2 sensor not reading correctly.

    Due to poor placement on a fender exhaust, my NTK WBO2 got hit by my tire after hitting a hole in the road. Ordered a new sensor and plugged it in to find my AFR being stuck at 27.1. Loaded multiple tunes to my Dominator ECU and nothing changed the AFR. First thought was I received a bad NTK sensor. I plugged it into my buddy's car and it read perfectly fine and changed as it should. My initial thought was when it got hit with power on maybe I shorted something in the ECU. I sent it back to Holley and all ports tested as working correctly. Today I tested all the wires in the main harness for continuity from plug to plug. All tested correctly. However, I then realized that while the power is on, the sensor started reaching temperatures that made it unable to be held in my hand. I turned power on to my buddy's car and his sensor doesn't get nearly that hot without running. Anyone ever had an issue like this or know of anything else to check aside from ordering the secondary WBO2 harness?

  2. #2

    Default WBO2 Wiring Schematics

    I found the schematics on what pins are what. But I'm mainly curious if any of those wires contain anything that would change the rate of electrical flow in any of the wires? Or does anyone know what voltage the heater wire in the harness should be putting out with power on?

  3. #3
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,685

    Default

    Read section 1.2-1.5 - "Heater Supply", pages 3 & 4: http://www.not2fast.com/instrumentat...03mar21eng.pdf (Bosch LSU4.2 WBO2 Sensor Specifications)
    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.

  4. #4

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    Thank you Danny. Is it different for the NTK WBO2 sensor?

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,685

    Default

    I don't know about the actual heater regulated voltages, but the WBO2 sensor pin-out is the same.
    http://forums.holley.com/showthread....ension-Harness (Read "Wideband O2 Sensor Notes")

    Diagnose The Following:
    All sensor values correct on Data Monitor?
    Failed WBO2 sensor corrupted Learn Table (unusual %)?
    Exhaust leaks upstream of the WBO2 sensor?
    Sufficient length of exhaust piping beyond WBO2 sensor?
    Ignition misfire? (WBO2 sensor will read lean.)
    Battery/charging system functioning properly?
    Consistent fuel pressure? (Disconnect vacuum hose to measure static psi.)
    Inspect wire harness/connectors for damage and ensure it's not near any high voltage components.

    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).

    Troubleshooting & Testing:
    https://www.holley.com/document/tech...__statuses.pdf (Sensor Diagnostics & Statuses)
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual & Diagrams)
    http://forums.holley.com/showthread....ist-Holley-EFI (Troubleshooting Checklist - Holley EFI)
    https://forums.holley.com/showthread...7668#post87668 ("Test Relay" for troubleshooting/diagnosis.)
    https://www.youtube.com/watch?v=rmnxKLjM25g (Wideband O2 Sensor Test/Diagnosis - it works!)
    If testing the WBO2 sensor key-on/engine-off, the sensor heater will time out, so you'll need to work fast.
    If you need more time, the WBO2 sensor test can be performed with the engine running in Open Loop mode.
    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.

  6. #6

    Default

    Danny, as for your diagnostic list:
    -As far as I can tell all sensor values are correct. The AFR read correctly before the last sensor got damaged. I haven't changed anything except placement of the WBO2 bung and a new sensor.
    -As far as a corrupted Learn Table, I have uploaded multiple tunes, not just the one I was using when the sensor was damaged.
    -I fixed the exhaust leak upstream.
    -There is about 2 feet of exhaust after the WBO2.
    -No misfire that I'm aware of.
    -Battery/alternator working correctly.
    -Fuel pressure staying consistent (new regulator).
    -All wiring appears fine and are away from any high voltage components.
    I have not yet checked voltage to the sensor with key-on/engine-off yet. I just feel like something has to be wrong in the main harness as the sensor reads correctly on a different car. But all wires from WBO2 plug to ECU plug have continuity.

  7. #7
    Join Date
    Nov 2014
    Location
    Ont. Canada
    Posts
    1,384

    Default

    Can you plug your ECU into another car?

  8. #8

    Default

    Possibly. So far everyone is leery because they don't want me potentially corrupting their wiring ha, ha. Holley tech told me my WBO2 circuit in the ECU may be fried, so I'm gonna have to order the second harness unless I can repin the one I have.

  9. #9

    Default

    Did you ever resolve this issue? I'm having the same problem. AFR stuck at 27.3, tried two new WBO2 sensors, switching WBO2 to other header, adding and subtracting fuel from map, WBO2 harness is good. I emailed Holley a datalog two days ago and still haven't heard back. Car runs and drives great in Open Loop.

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