GT500 plug reading? Bad o2 sensor?

Discussion in '2007+ Mustang GT500 Tech' started by AbdullaGT500, Nov 28, 2016.

  1. AbdullaGT500

    AbdullaGT500 forum member

    Age:
    26
    4,482
    0
    My 14 GT500 has a slight hesitation/misfire. Pulled the plugs today and found Bank 2 to be completely fouled. Bank 1 looks great. Does this look like the o2 sensor is stuck lean on bank 2? Also did a log on my SCT and Bank 2 was pegged lean and did not move, while bank 1 fluctuated around normal.
     

    Attached Files:

  2. 07gts197

    07gts197 forum member

    671
    20
    Are there any codes? Have you checked timing?
     
  3. G.T

    G.T Senior Member

    1,234
    17
    your cats are plugged up on one side.
     
  4. redfirepearlgt

    redfirepearlgt forum member

    2,172
    74
    Jumping in full tilt, regardless of CEL's I'd first check for any obvious exhaust leak between the exhaust manifold up to the O2 sensor on bank two. Exhaust leaks small or large will effect the O2 sensor reading which will give a false lean indication when in fact the A/F Ratio in the combustion chamber is fine otherwise. This causes the PCM to add pulsewidth to the injectors introducing more fuel into the cylinder. If the O2 sensor has failed and is putting out little to no voltage, again the PCM thinks the sensor is seeing a lean condition and increases fuel (pulsewidth on the FI) when in fact the ratio was fine to begin with.

    The rear O2 sensor should detect a failure or clog in the Cat IF IT HAS NOT BEEN TURNED OFF IN A TUNE. Visual inspection of the Cat would indicate a possible clog, as bank 2 which is on the driver's side would show signs of extreme heat up near the entry of the cat. Plus chances are you would feel warmer than usual temps near your foot when driving. While there is the H-pipe in the system it may also still be possible to feel heavier exhaust flow on the passenger side rear than the drivers side rear...maybe. The eyeball inspection of the cat and the hotter floor board temps on the driver's side would be the better tell tails.

    Hope this helps.
     
    Last edited: Nov 29, 2016
  5. AbdullaGT500

    AbdullaGT500 forum member

    Age:
    26
    4,482
    0
    There are no codes present. No cats on the car. VMP tune, long tube headers, off road x pipe, o2 extensions and other bolt ons are the mods. No leaks are present either. Rear o2s are switched off. It is definitely dumping fuel on that side. I'll check the o2 extensions and sensor tonight.
     
  6. ILW84U

    ILW84U Senior Member S197 Team Member

    Age:
    59
    1,127
    7
    O2 extensions are a no no on these cars.
     
  7. redfirepearlgt

    redfirepearlgt forum member

    2,172
    74
    Swap O2's if you see no indications of burned or broken wiring on bank 2 harness. Obviously we are hoping that the symptom moves to bank 1. Then you know its the O2 sensor.
     
  8. AbdullaGT500

    AbdullaGT500 forum member

    Age:
    26
    4,482
    0
    That's what I've read. I just don't see any way of getting the plugs to reach without them.

    That's the plan tonight. I'll hopefully have a spare o2 sensor by then just in case.
     
  9. BruceH

    BruceH BBB Big Bore Boss 322 Staff Member S197 Team Member

    13,802
    6
    It's a factory wideband, correct? It's pegged for sure and overfueling the whole bank. Why it's pegged is the question. Sensor or extension?
     
  10. AbdullaGT500

    AbdullaGT500 forum member

    Age:
    26
    4,482
    0
    Yes it is the factory wideband o2. I just realized it was the first time I'd driven the car in the rain since I put the headers on, next start up is when this happened. I wonder if the extensions are more sensitive to water than the factory plug ins? Not feeling so great today so will have to work on it tomorrow.
     
  11. ILW84U

    ILW84U Senior Member S197 Team Member

    Age:
    59
    1,127
    7
    Here is what I found on another forum.

    Disconnect the front and rear O2 sensors from the exhaust.

    Trace the wiring harness down from the passenger side and it will attach to the bell housing and transmission on the driver side.

    Remove all push pins and attachment points and flop the wiring harness from the driver side to the passenger side.

    Pull the wiring harness from below with just a little force to remove slack in the harness.

    Re-install all O2's with no extensions.
     
  12. Speedboosted

    Speedboosted Found missing cylinders

    933
    5
    This is correct. It's pretty simple to do and really saves the life of the sensors as well as gives more accurate readings.
     
  13. AbdullaGT500

    AbdullaGT500 forum member

    Age:
    26
    4,482
    0
    Looks like the o2 sensor itself is the culprit. First, I removed the extension and plugged it in directly, still same issue. Swapped it over to Bank 1 and the readings moved along with it. I completely forgot to order one the other day, so hopefully I can get one locally tomorrow. I will be doing a clutch swap this weekend so that will be a good time to go through and stretch out the harness so I can make sure the wires are comfortable and not being stretched too far.
     

    Attached Files:

  14. redfirepearlgt

    redfirepearlgt forum member

    2,172
    74
    Figured that was the culprit. Good trouble shooting.

    Mark those harnesses well. Getting them crossed is a common OH-OH when doing a clutch swap. Label properly once...plug in properly once.
     
  15. AbdullaGT500

    AbdullaGT500 forum member

    Age:
    26
    4,482
    0
    Thanks for the tips everyone. Got this one resolved, good as new! New Bosch sensor was around $50.
     
  16. BruceH

    BruceH BBB Big Bore Boss 322 Staff Member S197 Team Member

    13,802
    6
    That's always a good feeling!
     
  17. bujeezus

    bujeezus forum member

    2,664
    67
    Good job man. Glad it wasn't somethin serious.
     
  18. redfirepearlgt

    redfirepearlgt forum member

    2,172
    74
    you da man!!!
     
  19. AbdullaGT500

    AbdullaGT500 forum member

    Age:
    26
    4,482
    0
    Thanks guys! Glad it was an easy problem to diagnose/fix. Also did my clutch swap today and managed to get the o2 sensors to plug in without the extensions! :clap: