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Air pump S90-V90

posted by  sixvolvos on  Thu Sep 16 13:47 CST 2010
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last visit: Tue Mar 5 07:57 CST 2013
[RELATED]

Group:
'98 S90 with 152K miles has air pump coming on after I drive it a bit.
Only at idle as far as I know, but maybe I just cannot hear it while driving.
I hear it when stopped at a light
Spins up, runs for 3-5 seconds, then spins down.
Outside temp from 60 to 80 degrees, engine is warmed up by then.
Why is it doing this?

Original O2 sensors. Are they involved in this?
Do I need a new front one or both?

Searching results only in 850/V70 info and I'm not sure advice applies.
Anyway this scenario is not mentioned.

Who has info?

Thanks,
Sixvolvos








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    Air pump S90-V90

    posted by  david hunter on  Mon Sep 27 16:53 CST 2010
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    last visit: Mon Jun 30 22:10 CST 2014
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    When the air pump comes on at idle after warm up it is simply perfroming a programmed test by dumping fresh air into to the exhaust flow while the ECU looks for certains changes from the O2 sensors, if the test does not complete you will get a CEL with a fault code. The test will be performed during an extended idle time such as at a light, if it is cut short it will do later.

    Are you getting a CEL Light and code?
    --
    David Hunter








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    Air pump S90-V90

    posted by  sixvolvos on  Fri Sep 24 02:58 CST 2010
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    last visit: Tue Mar 5 07:57 CST 2013
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    PROBLEM SOLVED!
    There is no problem.
    From Alldata, paraphrasing:
    The air pump comes on 12 seconds after the engine is started and if the engine temp is between -12 F and +95 F.
    Then it runs for 70 seconds.
    It starts again sometime after 10 minutes of engine running when the system is doing a diagnosis.

    So it is supposed to come on, and I hear it because the pump is getting noisy.

    Sixvolvos








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    Air pump S90-V90

    uid 11021's pic
    posted by  dewfpo on  Fri Sep 17 16:55 CST 2010
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    last visit: Thu Oct 23 18:34 CST 2014
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    I've had mine do this once when I started it on a cold day, backed it out of the garage and let it idle in the driveway to warm up as I shoveled the walk and after a few minutes of idling the air pump came back on. It was the first time I noticed it but I came to the conclusion that the cat had cooled off since I wasn't driving it and it was very cold outside. My understanding is that the air pump helps get the cat up to temp on a cold engine. So.... that being said, it's possible your O2 sensor is going bad and giving false readings to the ECM so it turns on the air pump because it thinks the cat is not up to temp OR, your cat is actually going bad. At least that's the determination I came too but I haven't proven any of it.

    DEWFPO
    --
    1998 S90 083,228 and 1995 964 154,100








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      Air pump S90-V90

      posted by  sixvolvos on  Sat Sep 18 05:24 CST 2010
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      last visit: Tue Mar 5 07:57 CST 2013
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      Dewfpo:
      I don't want to hear about a bad cat!
      Very expensive.
      How do you test one?
      I understand that they can get plugged up or collapse inside.
      The car seems to have the same power as always, and I use it frequently while pulling a trailer up hills.

      So I understand that the O2 sensor is involved.
      Best to change that first?

      Sixvolvos








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        Air pump S90-V90

        uid 11021's pic
        posted by  dewfpo on  Sat Sep 18 09:53 CST 2010
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        last visit: Thu Oct 23 18:34 CST 2014
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        In this particular case a bad cat has nothing to do about plugging up. It has to do with the precious metals in it being used up and it no longer catalyzes the HC's. I would first check the rear O2 sensor and see if it's working properly. A search should yield you the correct way to measure the voltages and see what the readings are. That will tell you if the O2 sensor is functioning properly, if it is, then the cat may be bad. The rear O2 sensor is a simple sensor and is only used to see if the cat is working properly.

        An alternative method.....

        If you have a IR thermometer gun, you can check the temps at the front of the cat and at the rear of the cat after it is good and hot. If the front is hotter than the rear, then the cat is likely dead. If the rear is hotter than the front by at least 100 degrees then there is still some life left in it. A perfectly operating cat may be several hundred degrees hotter at the rear than the front.

        Hope this helps.

        DEWFPO
        --
        1998 S90 083,228 and 1995 964 154,100







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