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O2 Sensors

Discussion in 'General Tech and Maintenance' started by Prowler, Jun 16, 2005.

  1. Prowler

    Prowler Super Moderator

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    My car is OBDII, so I have two o2 sensors. One before the cat and one after.

    I started getting a CEL when I put on my header. It was made for the D16Z6 and I have a D16Y8. My factory o2 sensor is at the top of the exhaust manifold, but the header has it at the end of the header. I had to lengthen the wires quite a bit, and since then, the CEL goes on. I pulled the code at an automotive place and it says Slow Response From O2 Sensor. Once reseted, the CEL would come on about once every two weeks.

    Now I put on a high flow cat. The problem was the O2 sensor bungs were in front of the cat, so my first and second O2 sensor are right next to each other. I did some research and found that the first O2 sensor is responsible for making sure of the 14.7:1 air-fuel mixture is correct and makes adjustments based on it's reading and the second O2 sensor makes a comparison to see what the cat burns off.

    What should I do? I believe the engine just goes with a generic air-fuel mixture when it can't get a reading from the O2 sensor. And VTEC still kicks in, so the CEL isn't affecting that fortunately. Everything runs fine. But now I have a constant CEL on from the O2 sensors. Is there a way to bypass this at all?
     
  2. xj0hnx

    xj0hnx I wanna be sedated VIP

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    Cut off the flanges on the cat, weld them on the other sides and reinstall it so now the o2 is where it wants to be, and drill a hole in one of the runners and weld an o2 bung, so it is where it wants to be. That's the only way I know of.
     
  3. pissedoffsol

    pissedoffsol RETIRED

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    i can't beleive you're throwing a code for being
    "too far down" the stream. i've never heard of that ever.

    imo, the easiest way to fix your problem, is to get a jumper harness and a p28. screw obd2.
     
  4. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    Doesnt seem right to me either...gonna be a stupid question, but what gauge wire did you use when you lengthened the O2 sensor wire...if its something like 14 do you think that might cause a "Slow Response" due to the added resistance of high gauge (larger) wire.
     
  5. Prowler

    Prowler Super Moderator

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    Not sure on the wiring, but I believe it's probably 18 gauge. I didn't lenghten the wires, the shop that put the header on did. And don't even say anything about paying for the install.... it was a long story and I had no where to work on my car in Idaho while in college.
     
  6. Prowler

    Prowler Super Moderator

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  7. jamesA

    jamesA Well known pissed off telephone guy VIP

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    Are you sure it's throwing it because it's "too far down"? It sounds like the wire splicing is slowing the pulse from the o2 sensor to the ecu. Same thing happens when you see morons who splice cat5 networking wire with scotch locks. Slowed reaction times, etc.
     
  8. Prowler

    Prowler Super Moderator

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    What are scotch locks?

    BTW, it's not like wires for the o2 sensor need so many twists per foot for electro-magnetic interferance.
     
  9. pissedoffsol

    pissedoffsol RETIRED

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    phearable.net can set you up with a p28 with the different vtec point and revlimiter raised/speed governer removed... for 175 shipped including the p28

    just be sure what you're doing with changing the vtec point... might actually slow you down.
     
  10. jamesA

    jamesA Well known pissed off telephone guy VIP

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    scotch locks are little pieces of plastic you stick two wires in and crimp down on to close the connection. Good for phone wire, bad for network wire.

    Anyway, I'm talking about where it was spliced at might be opening the current to a faster path to the ground, meaning the ECU isn't going to receive the pulses.
     
  11. Prowler

    Prowler Super Moderator

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    You wouldn't recommend a lower crossover point?
     
  12. pissedoffsol

    pissedoffsol RETIRED

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    no... not at all.

    in fact, every car i've been turning with/seen graphs of before after, 95% of them needed a raise in the vtec point.

    if you switch lobes too early, you're just going to bog down
     
  13. Prowler

    Prowler Super Moderator

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    The P28 wouldn't fix the first CEL code I'm getting tho, just the second. Should I just wait and get a basemap done when the car is supercharged? Would that take care of the fuel management enough? Because there is no one here in town or within a days drive that can do dyno tuning or do Hondata/Uberdate/Crome...
     
  14. Prowler

    Prowler Super Moderator

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