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CO test point pigtal - no pulsating signal - only constant voltage ? 200

posted by  p3pete on  Thu Jan 30 02:09 CST 2003
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I am trying to check the CO at the pigtal as outlined in www.mvpvolvo.com 12 v LED method ( pigtail wires are pink , white with blue stripe ). The LED does not pulse , staying lit all the time . Adjustment of of the AMM potentiometer/aka mixture screw doesn't affect it or how the engine runs (which actually runs ok ) . O2 sensor is fine , AMM does have resistance between terminals 2-6. Does this mean computer is in limp or not in idle mode ? What do I check out next ? I regret having only a Haynes manual at this time and really some need some help . - thanks

( 007 computer, 007 AMM )








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    CO test point pigtal - no pulsating signal - only constant voltage ? 200

    posted by  p3pete on  Thu Jan 30 07:38 CST 2003
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    Update - I have clean the throttle body (left on the car , cleaned with spray card cleaner and toothbrush ) . Now I can get a change of mixture ( engine idle drops and runs a little rough ) when disconnecting the 02 sensor wire . The LED ( connected between + battery terminal and the white/blue stripe wire is still staying lit . What next ?








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      CO test point pigtal - no pulsating signal - only constant voltage ? 200

      uid 27's pic
      posted by  Art Benstein on  Thu Jan 30 14:36 CST 2003
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      last visit: Fri Oct 17 20:10 CST 2014
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      If your oxygen sensor is flipping between .2 and .8V your mixture test point should be flashing the LED at the same rate. That assumes everything between the sensor and the test point is in order; ECU, connectors, harness... But I think the LED should be connected to the pink wire, if I remember LH2.2 is what you have. Whichever wire, it is the one that goes to pin 22 on the ECU.

      The blue-white lead is to be grounded to disable the idle air control motor so you can set the base idle with the big air bypass screw on the throttle body.

      I just checked my Haynes, the manual I mean, it is 1994, apparently one printing later than yours. But LH2.2 was pretty much played out by 1990, 1988 for the 240.

      --
      Art Benstein near Baltimore








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        CO test point pigtal - no pulsating signal - only constant voltage ? 200

        posted by  p3pete on  Fri Jan 31 01:26 CST 2003
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        I re-checked everything again and disconnected the battery overnight . I tried again this AM and the LED flashed and could adjust the CO . I don't know if discoonecting power to the computer had anything to do with it or this was just another symptom of a bad wiring harness ( I have repair the area near the gray connector . Thank for all your help . After the emissions test, on to my bad wiper motor project...... :)



        The www.mvpvolvo.com " Setting Your Base Idle Specs on cars with LH- 2.1 and LH2.2 Jetronic fuel injection " - ( find it with site map link on main web page ) talks about a red/white wire and green white wire at the test port pigtail . These apparent correspond to the pink and white/blue stripe wires on the pigtail of my 1985 . It sure would have been nice for Bosch/Volvo to have been more consistent about this .







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          CO test point pigtal - no pulsating signal - only constant voltage ? 200

          uid 27's pic
          posted by  Art Benstein on  Fri Jan 31 02:33 CST 2003
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          last visit: Fri Oct 17 20:10 CST 2014
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          I'm thrilled you got that light to blink. I looked at that mvp site a week ago, maybe your original post?, and recall thinking something was amiss. But I only know LH2.2 from the books and other bricksters, my cars are k-jet(1), LH2.0(1) and LH2.4(4). I figured maybe someone changed the harness between 85 and 88.

          --
          Art Benstein near Baltimore








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            CO test point pigtal - no pulsating signal - only constant voltage ? 200

            posted by  p3pete on  Fri Jan 31 05:33 CST 2003
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            Also - Today I lookied at newer editon copyright 1998 of the Haynes .
            The LH-2.2 Jetronic info is much better than what they put in my 1990 version . However I am keeping my eye for a deal Bentley manual. - thanks








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              Haynes and Bentley 200

              uid 27's pic
              posted by  Art Benstein on  Fri Jan 31 05:54 CST 2003
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              1998. That's interesting. Mine is 1994 and the last 240 was made in 93, so I figured that was it for Haynes. Maybe there will be some corrections. I'll definitely have a look at one.

              I like the photography in Haynes. Bentley covers the model a bit differently such that I like having both to use. I think Ebay may be the least expensive source for a Robert Bentley.
              --
              Art Benstein near Baltimore








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    CO test point pigtal - no pulsating signal - only constant voltage ? 200

    uid 27's pic
    posted by  Art Benstein on  Thu Jan 30 04:59 CST 2003
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    last visit: Fri Oct 17 20:10 CST 2014
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    "O2 sensor is fine " Do you know this because the part is new?

    The output of the pink lead follows the transitions of the oxygen sensor. I'm pretty sure Haynes has everything Bentley has on this subject. If something (a vague term I realize) is forcing your motor to run very lean or very rich it will be beyond control of the oxygen sensor feedback resulting in the CO test point indications you are experiencing. The adjustment on the AMM is not broad enough to make up for gross vacuum leaks, bad sensors/wiring, clogged injectors, or other problems resulting in too lean or too rich.

    I can't recall whether the LED on is rich or lean, but a quick measurement of the oxygen sensor will reveal the truth; roughly > 500 mV rich, < 500 mV lean.
    --
    Art Benstein near Baltimore








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      CO test point pigtal - no pulsating signal - only constant voltage ? 200

      posted by  p3pete on  Thu Jan 30 05:58 CST 2003
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      I forgot to add - My haynes Volvo 240 Series manual has a 1990 copyright date . Is there more ( or better ) LH-2.2 information the later editions ?








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      CO test point pigtail - no pulsating signal - only constant voltage ? 200

      posted by  p3pete on  Thu Jan 30 05:37 CST 2003
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      Thanks for you reply Art . I first replaced the O2 sensor thinking it might be the problem - the voltage at idle fluctuates between 0.3-0.7 V and is somewhat lower when the engine run at higher rpms . I believe ( okay this is strect ) that LED on is idicative of the rich mixture and that the O2 system is putting out more voltage to tell the system to lean the mixture . I initally looked for broken and damage hoses but it sounds like I better look again . - Pete







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