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Emissions 850

posted by  rjcarne on  Thu Jul 26 09:43 CST 2012
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last visit: Thu Jul 26 17:10 CST 2012
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my 1993 volvo 850 GLT VIN YV1LS5507P2094366 failed State emission test. NOx (ppm) standard 848/RPM 2293 reading 1127 FAIL....at low speed RPM 472 standard 937 Reading 1730 FAIL. I was told to check and clean the EGR valve but my vintage does not have an EGR Valve (that is why I included the VIN). The DTC codes show 121 MAF signal and 223 IAC valve opening signal. I have no idea what these are or if they are accountable for the NOx failure. I have checked the vacuum hoses and replaced any bad ones, changed the spark plugs, used injector cleaner, changed the oil and filters, installed a new oxygen sensor. None of the above seemed to change anything. I can scan and include the "vehicle inspection reports if you need it








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    ANSWER Emissions 850

    posted by  KlausC on  Thu Jul 26 12:43 CST 2012
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    last visit: Fri Oct 24 10:15 CST 2014
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    The Idle Air Control(IAC) is just in front of the throttle body, an aluminum cylinder with 2 hoses, one going to the top of the vacuum tree. The IAC is probably very dirty. Remove it, spray throttle body cleaner in, shake it real good, repeat several times until it sounds real loose inside.

    The Mass Air Flow meter(MAF) is on the edge of the air cleaner box, where the air hose comes out and directs air to the throttle body. It probably needs to be replaced. There are different MAFs for turbo, NA, years, so make sure you get the correct one.
    The MAF determines the amount of air that passes through to the throttle body, so that the gas/air mixture is correct. There is a small pin like device that does the sensing, do NOT touch it with anything! There are MAF spray cleaners that sometimes work for a little while.

    --
    My name is Klaus and I am a V♂lv♂holic

    This post has been marked as an answer to the original question.



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      Emissions 850 1993

      posted by  someone claiming to be Ron Carne on  Mon Aug 6 15:30 CST 2012 [RELATED]

      Klause: I followed your advice and information along with buying a new air intake hose. I cleaned the MAF and cleaned the IAC, cleaned out the vacuum hose ports in the throttle body and the car passed emissions (NOx) inspection. Thank you for your help and advice.








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      Emissions 850

      posted by  rjcarne on  Thu Jul 26 12:56 CST 2012
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      last visit: Thu Jul 26 17:10 CST 2012
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      Thank you for your response. Great information. I have done some further research and discovered tha tmy air intake hose is also bad; I repaired it but have also ordered a new one online. I will definitely do the two things you recommended and see where it goes from here. Again, thanks fo ryour response.







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