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question about obd1 p28 CLOSED LOOP

Discussion in 'ECU's, Electronics, and Tuning' started by word, Aug 4, 2003.

  1. word

    word Senior Member

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    I've read from the Hondata website sent to me by one of the users here at hondaswap :worthy:

    http://www.hondata.com/techo2problem.html

    I am having the same problem as described before: ecu in the closed loop under light throttle and runs good with open loop, when under heavier throttle.

    From my understanding OBD0 and OBD2 both have 2 o2 sensors, and OBD1 only reads one, correct??

    I am only running 1 o2 sensor with an obd2 wiring harness, obd2-1 clip and a p28 obd1.

    I am trying to ask:

    According to the article I should not be having this problem, is it because the the ECU's reading from the plug that's not plugged into the o2 sensor? If the obd1 p28 ECU gets no readings from the o2 sensor what would happen? and lastly, p28 only reads one o2 sensor correct???

    thanks.
     
  2. blundar

    blundar Senior Member

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    OBD1 ECUs need one sensor. If you have a second sensor installed, it isn't being used. Stop worrying.
     
  3. pissedoffsol

    pissedoffsol RETIRED

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    yup- its all about the computer, not the wiring.

    and some obd0 only have 1 o2 sensor as well.. mostly the b-seires had the dual o2's

    verify that you have the PRIMARY o2 sensor plugged in to the wiring into the ecu.
    if thats the case, verify that your harness has been wired corectly, using our pinout guide... http://www.hondaswap.com/swap/viewer.php?id=58
     
  4. 89honda90

    89honda90 Junior Member

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    so does p28 have one or two o2 sensors?



    zach :blink:
     
  5. pills_PMD

    pills_PMD Super Moderator

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    it only looks for one
     
  6. word

    word Senior Member

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    sooo,

    when driving under normal conditions the ecu runs in closed loop, detecting the o2 sensor signals, and when under heavy acceleration the ecu runs in open loop?

    i just got a reply from hondata saying that the closed loop problem is only for obd0 ecu's. he said my problem is lack of tuning and i'm running too rich but my car isn't even boosted i don't see how a generic basemap would throw the a/f off to the point where my engine'd boggle.

    i am out of the country right now so i can't get to my car and see if the o2 sensor is the primary. would this be the culprit of my problem? what would happen if the ecu's in closed loop but detects no readings from the o2 sensor??

    thank you guys.
     
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