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Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

posted by  Lukester on  Sat Jul 8 10:19 CST 2006
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last visit: Sat Mar 28 12:50 CST 2009
[RELATED]

That shade tree mechanic being me! It all started off with an oil change, then I decided to clean my Throttle Body. That progressed to removing the IAC and cleaning it too. Put everything back together and now the car idles waaaay too high and is seeking up and down! Did I put the the Air Mass Sensor back in wrong? Does the it matter which way it goes in? I put it in so the holes were facing the airstream or direction of airflow. I removed the Air Mass Sensor completely and the idle wasn't as high, but it was still a bit high and continued to seek up and down. I don't know what I did? Any ideas out there? The throttle body wasn't that dirty by the way. Can't believe I did this to a perfectly good running car. This is a 93 940, non turbo.

Thanks,

Luke
--
89 244 195K+, 93 944 91K+








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    Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

    posted by  someone claiming to be HenryC on  Sun Jul 9 05:34 CST 2006 [RELATED]

    I had a similar problem with a 90 16 valve engine after I cleaned and adjusted the throttle disc per the instructions in the green EFI manual. It turned out that I had set the throttle disc too open and the extra air was confusing the EFI computer. Something like that could have happened when you cleaned yours.

    I would recommend talking another look at the throttle body.

    The instructions --

    - loosen the set screw for the disc so that it closes completely
    - loosen the two small screws holding the disc in the throttle body
    - open and close the throttle to seat the disc
    - hold it up to the light to confirm that it is centered
    - tighten the two screws that hold the throttle disc
    - screw in the adjustment screw so that it just touches the link rod
    - screw in the adjustment screw 1/4 turn and lock it down

    My problem was that I had turned the adjustment screw a complete turn instead of a 1/4 turn. It was a perplexing problem.

    Good luck







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    Just had another idea 900

    posted by  someone claiming to be tjts1 on  Sat Jul 8 15:08 CST 2006 [RELATED]

    It could be that after you reinstalled the throttle body, the throttle place became stuck slightly open. This can be adjusted for by turning double ended screw that is connected between the throttle body and the throttle cable. Basicly pull the intake bellows between the AMM and TB and check that the throttle body is completely closed. Just an idea. Hope it helps and it doesn't waste your time.
    Good luck
    Justin








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      edit 900

      posted by  someone claiming to be tjts1 on  Sat Jul 8 15:08 CST 2006 [RELATED]

      meant to say "throttle plate" not throttle place








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        OOPS never mind. strike that idea 900

        posted by  someone claiming to be tjts1 on  Sat Jul 8 15:11 CST 2006 [RELATED]

        I just read the part where you said you didn't actually remove the TB. sorry.








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    Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

    posted by  Lukester on  Sat Jul 8 10:47 CST 2006
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    last visit: Sat Mar 28 12:50 CST 2009
    [RELATED]

    To add or clarify to the above. I did not actually remove the TB. I just sprayed carb cleaner and used a brush to clean the inside. Also moved the valve open and closed a few times while cleaning. I also did not remove or mess with the TPS other than disconnect, clean with electrical contact cleaner, then reconnect the connection.

    Luke
    --
    89 244 195K+, 93 944 91K+








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    Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

    posted by  someone claiming to be tjts1 on  Sat Jul 8 10:46 CST 2006 [RELATED]

    While the engine is idling, squeze the hose going to the idle air control valve. If the idle slows down or the engine stalls the IAC is functioning normally. If there is no change then your AMM is fine and the problem is with the IAC.At least this way you isolate the problem to one or the other. Also check that everything is plugged back in to the wiring harness: AMM, IAC, throttle body or anything else you might have moved. I've made that mistake before.
    Good luck
    Justin








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      Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

      posted by  Lukester on  Sat Jul 8 13:17 CST 2006
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      last visit: Sat Mar 28 12:50 CST 2009
      [RELATED]

      tjts1, Thanks for the good advice. I did just as you recommended and sure enough, I squeezed the hose going into the IAC and the high idle did slow a little bit. At least I can rule out a bad IAC. I hope when removing the AMM, I didn't damage the sensor somehow. Does anyone know if the AMM sensor has a particular way it goes back in? I put it back in so that the squeeze connector wire is facing down toward the pavement. That put the holes facing on the sensor facing into the direction of the airflow. I suppose I could experiment with that and turn it in differnt directions just to see what happens. I took pictures. Does anyone know how to post pictures here on Brickboard?

      Luke
      --
      89 244 195K+, 93 944 91K+








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        Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

        posted by  gopeshs on  Sat Jul 8 13:29 CST 2006
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        last visit: Mon May 19 14:01 CST 2014
        [RELATED]

        My two cents
        some say if you remove the AMM electrical connection and then if the idel become too bad (Too high) then AMM is OK if no change happens then AMM is bad.
        Regards
        Gopesh








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          Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

          posted by  Lukester on  Sat Jul 8 13:50 CST 2006
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          last visit: Sat Mar 28 12:50 CST 2009
          [RELATED]

          gopeshs, I started the car. It idled very high. I disconnected and reconnected the electrical connector to the AMM and there was no change to the idle speed. Maybe the AMM is bad afterall. I still don't get it though as it was working fine until I removed the sensor from the tube.

          Luke
          --
          89 244 195K+, 93 944 91K+








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            Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

            posted by  gopeshs on  Sat Jul 8 14:10 CST 2006
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            last visit: Mon May 19 14:01 CST 2014
            [RELATED]

            probably AMM connections are loose some where. I once did this to my car. When the car was idling I removed the AMM elstrical connection The car's idle speed all of susdden became high (close to 2K) Then when I reconnected it became normal . This all I did when I was doing exactly what you did (ie Trying to do preventive maintainence in a good running car)
            Regards
            Gopesh








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              Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900

              posted by  Lukester on  Sun Jul 9 03:53 CST 2006
              Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
              last visit: Sat Mar 28 12:50 CST 2009
              [RELATED]

              Update. I dug a bit deeper. I don't have an AMM. I have an Air Temp Sensor. I now have a check engine light and fault codes indicating a bad Air Temp Sensor and a bad IAC. It is either one or the other or both. Today I will disconnect and reconnect both. I don't know what else to do other than start replacing parts.

              Anyone else have any ideas here?

              Thanks,
              Luke
              --
              89 244 195K+, 93 944 91K+








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                Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900 1993

                uid 18083's pic
                posted by  lucid on  Sun Jul 9 04:35 CST 2006
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                last visit: Fri Oct 24 12:31 CST 2014
                [RELATED]

                I've been meaning to break in with the "no AMM". Most if not all U.S '93 940's have Regina FI. If you tried starting with the Air Temp Sensor unplugged, that would set code 1-2-2 and the CEL.

                The idle problem is probably just a loose connector (code 2-2-3?), assuming you didn't have that problem before your maintenance efforts.

                Those codes aren't saying anything is necessarily "bad", just that the expected signal(s) are missing—as when a connector is unplugged or not properly seated.
                --
                Bruce Young
                '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.








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                  Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900 1993

                  posted by  Lukester on  Sun Jul 9 05:17 CST 2006
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                  last visit: Sat Mar 28 12:50 CST 2009
                  [RELATED]

                  Bruce,

                  You hit it on the head. I got codes 1-2-2 and 2-3-3. It acts as if the Air Temp Sensor and IAC are not connected, but they are. Other than disconnecting and reconnecting, anything you recommend?


                  Luke
                  --
                  89 244 195K+, 93 944 91K+








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                    Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900 1993

                    uid 18083's pic
                    posted by  lucid on  Sun Jul 9 07:13 CST 2006
                    Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
                    last visit: Fri Oct 24 12:31 CST 2014
                    [RELATED]

                    Delete the fault codes, then see if they stay gone.

                    1) Press OBD button for about 5 seconds the let go.

                    2) When LED lights up, Press again for 5 seconds

                    3) Read codes again -- should only be 1-1-1
                    --
                    Bruce Young
                    '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.








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                      Shade Tree Mechanic Makes Mistake with IAC and Air Mass Sensor. Help! 900 1993

                      posted by  Lukester on  Sun Jul 9 08:28 CST 2006
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                      last visit: Sat Mar 28 12:50 CST 2009
                      [RELATED]

                      Bruce,

                      You are right again! Cleared the codes and all is well with the world. Took the car around the block and she seems to be fine with the exception of a slightly higher than normal idle speed. Maybe that will go away eventually. However, the excessively high idle and seeking up and down is gone.
                      I little bit of knowledge in my case can be a dangerous thing. Maybe I should reconsider retiling the bathroom floor myself.

                      Luke
                      --
                      89 244 195K+, 93 944 91K+







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