Passing TX emissions/eng lean issues...help please...

Discussion in '94-95 5.0 - Specific' started by TX_Snake, Aug 13, 2016.

  1. TX_Snake

    TX_Snake New Member

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    Dallas TX
    My car is having trouble passing emissions in TX. I could use some guidance from the collective wisdom here....

    Most recent inspecting report from this past week indicates a well running car minus a failure at high speed test for NOx. Prior to this test I have replaced (all since april) plugs, wires, cap/rotor. All oem spec parts from O'reillys, no performance parts. I recently installed new flowmaster 2.5" mini cats as well. maybe 150mi on the cats. Using a friends Matco Monitor 4000 Enhanced scanner, I retrieved the following codes last night after driving home approx 30mi hwy in 107+ temp.

    KOEO
    564- Fan control circuit failure KOEO ( I do hear both fan speeds come on during the test though...)
    181- Fuel system at rich adaptive limit at part throttle, system lean B1
    186- Injector pulse width higher than expected (with BARO sensor) (BARO=barametric psi?)
    189- Fuel system at rich adaptive limit part throttle, system lean B2
    KOER-PASS and Cylinder Balance Test PASS

    After some google fueld semi professional amateur guestadiagnostics, I replace my O2 sensors with NTK sensors as a place to start.

    Drove home tonight, same mileage, approx 90* temp and pulled the following codes.
    KOEO
    564 2x
    SEPARATOR 10
    Keep alive memory codes
    181 2x

    I then ran the fast codes option on the scanner and came up no codes. Re ran the slow code option and got a KAM codes PASS...which I thought was strange...
    KOER codes were
    172- Lack of heated Oxygen Sensor (HO2s-1) switches, indicates lean B1
    136- Lack of heated Oxygen Senosr (HO2s-2) switch during KOER, indicates lean B2
    CBT PASS

    I will clear the codes in the morning and go drive the car since I have not cleared the codes since installing the O2 sensors.

    I know high NOx is caused by high combustion cylinder temps, and I clearly have a lean eng condition, but I'm not sure how to correctly identify the exact cause.
     
  2. TX_Snake

    TX_Snake New Member

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    [​IMG]
     
  3. TX_Snake

    TX_Snake New Member

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    Finally found the root of my problems. The MAF sensor had a low voltage output, indicating it was not functioning correctly. R/R the MAF sensor and reset timing to 10* from the 18* it was set at and now the car runs crisper, pulls harder ,and passed the test.
     
  4. Nighttrain

    Nighttrain Well-Known Member

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    Glad you got it figured out