"Cats" & Oxygen sensors question

Discussion in 'Mustang Chit Chat' started by Mike in SC, Jan 11, 2019.

  1. Mike in SC

    Mike in SC Lactation Consultant

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    While I had my 09 GT convertible I contributed regularly to this forum. Now that I have a 2014 GT coupe, I'm the one in need of direction.
    I just had installed a set of GT500 axle backs because the Roushs that came with the car were waay too loud. I also had a check engine light that was throwing codes P0420, P0430. This indicated a Cat converter prob. I reset them twice but they returned quickly. While my mechanic changed out the axle backs I had him research the codes. Here's the surprise- I got Cat eliminator pipes instead of actual Cats. The Oxygen sensors screw right into the pipes but those codes will never go away. Rock Auto has Cats them for approx $135 each which ain't too bad.

    I asked the mechanic how much for him to get the Cats and install them. He told me that the car normally has two Cats on each side and the price would be high. I did a little research and got the attached image off Tasca Parts and I'm only seeing two Cats (#1 & #2). I think that he's mistaking the resonators (around #6 & #7) as another set. Additionally, per the other image, I'm only seeing two Oxygen sensors and he told me a grand total of four. He advises to leave it as is and live with the check engine light. I am in South Carolina which has no inspection but it's technically illegal and I would like to correct it. Is he correct or not? TIA. 2014 exhaust system.png

    oxygen sensors.png
     
  2. oldVOR

    oldVOR forum member

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    There are two CAT's, one per side.
    There are four sensors, one up-stream and one down-stream of each CAT.
     
  3. Mike in SC

    Mike in SC Lactation Consultant

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    Ok, I was pretty sure about the Cats but unsure on the Sensors. Per the second image, would the upstream be #8 & 9 and the downstream #4? Thanks
     
  4. oldVOR

    oldVOR forum member

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    No, you need two #8's which are up-stream of the CATs and two #9's which are down-stream of the CATs

    #4 is part of #1 which is the fuel vapor recovery system
     
  5. Mike in SC

    Mike in SC Lactation Consultant

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    Great, that clears things up. Now I just gotta convince my mechanic. Appreciate it.
     
  6. 1950StangJump$

    1950StangJump$ forum member

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    Unless something changed since my 2011 Coyote . . . you are correct -- two total cats with 4 total O2s (one upstream and one downstream on each side). You are likely correct that he is confusing the resonator.

    If it were you, assuming that you don't have emissions where you live and don't have to worry about cats for a yearly inspection, then just have the REAR O2s turned off via a tune. That will get rid of the light. I'm reading that some companies are refusing to do that these days because of an alleged crackdown on it from the Feds. Mine did it . . . I just asked for it to be an "off road" tune.

    Alternatively, they make inserts for the rear O2s that fool it into thinking it is looking at post-catalytic air. I have never tried them, and I read mixed reviews on effectiveness.
     
  7. SuperSonic05

    SuperSonic05 forum member

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    okay, there are only one set of cats, in the first image they are #1 & 2, they are in the engine bay. there are O2 sensors right before and right afterward them (total of 4), the upstream sensors are on the exhaust manifolds and so aren't displayed on these images. I don't have resonators on my over axle exhaust pipe.
     
  8. Grabber Blue 5.0

    Grabber Blue 5.0 forum member

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    Must be a great mechanic if he doesn't know the difference between a catalytic converter and a resonator.
     
    skwerl likes this.
  9. oldVOR

    oldVOR forum member

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    I'd recommend a different mechanic....
     
  10. Mike in SC

    Mike in SC Lactation Consultant

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    Thinking along the same lines. LOL!
     
  11. Gabe

    Gabe Whippled Coyote

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    The other upstream O2 sensor is not visible, but there's one on each side,and 1 downstream on each side, behind each cat.
    TWO cats total, one on each side:

    20151001_exh09_arrows.jpg
     
  12. Riptide

    Riptide Will work for Mustang.

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    On the 6r80 car the rear narrow bands can be kind of a pita to get out of there. Not a lot of room to get a hand up and un-snap the sensor out of the harness at least on one side maybe both.

    I tried using some j-style defoulers on mine and the h-pip had to come out of the car no way around it even then the sensors barely reached.
     
  13. Gabe

    Gabe Whippled Coyote

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    The Coyote has factory rear wide band O2 sensors
     
  14. Riptide

    Riptide Will work for Mustang.

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  15. Gabe

    Gabe Whippled Coyote

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    I don't care for that dude.

    Putting that aside, I've always been told by many people that the rear O2's are wideband on the '11+ Mustang.

    Personally I'm using an Aeroforce gauge and I'm monitoring AF ratio through the OBD connection, reading the factory rear O2's, and I'm getting the usual readings I'd get if I had an aftermarket wideband installed.
    Pretty sure Pete @ Performance Dyno is one of the people that's told me they're wideband.
     
  16. 07 Boss

    07 Boss forum member

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    I don’t run cats and I pass smog with the 90* mini cats. They have worked for the last 2 yrs without a CEL and reading “ready” for the OBD scan.
    [​IMG]