US 86 328 GTS Emissions Question | FerrariChat

US 86 328 GTS Emissions Question

Discussion in 'Technical Q&A' started by 328GTSID, Jul 4, 2019.

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  1. 328GTSID

    328GTSID Rookie

    Jul 21, 2018
    17
    Full Name:
    Gene Axtell
    What values should I see in terms of CO, NOX, ETC. on my sniffer?

    Thank you in advance!
     
  2. 335s

    335s Formula Junior

    Jan 17, 2007
    870
    SF Bay Area
    Full Name:
    T. Monma
    FWIW:
    That is not really a meaningful diagnostic evaluation specification,,,,these numbers are set as LIMITS- on a gram per mile basis-sampled UNDER load, utilizing "constant volume sampling" method(17 bags)-ALL that the EPA requires in a "Small Volume Ceretificate of Manufacture, for passenger cars and light duty vehicles under 7500 lbs GVW is:
    X grams HC
    Y grams of CO
    Z grams of NOx
    and A grams of HC evap in the "SHED" after va 24 HR "hot soak"
    There are other more trace gasses-but this is the engineering problem...

    So long as the vehicle produces a PERCENTAGE of these limits at initial-new car miles-and an ACCEPTABLE INCREASE at specified mileage intervals up to the 50,000 mile end of required adherence to limits(these are what are called: "deterioration factors", absolute numbers don't really matter...

    So long as the system is stochiometric: under cruise speed testing: the car "blows zeros". There are transient spike based on acceleration(going up hills), hot restart etc... in this era, it was called "The LAS-55(505 seconds of a driving test simulating a cold start and driving a trace pattern simulating rush hour traffic on the 405 at rush hour: pretty good testing criteria! It was determined in the late 1980s that 90-95% HC emissions actually were taking place at the point of fueling...evap is a huge issue-hence modern cars being so sensitive to this criteria.

    ANY values taken post catalyst-unless grossly out of range, are usually previously indicating by poor runing. Imnpropere gas numbers are more typically indicating a fouled catalyst bed...IMO(5-6 years in a Federal testing facility in the late 70s to mid 80s)
     
  3. PT 328

    PT 328 F1 Rookie
    Silver Subscribed

    May 1, 2005
    3,955
    Here are my results I posted a few years ago. It smogged cleaner than my wife's Lexus.

    [​IMG]
     
  4. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,238
    Frederick, Maryland
    Full Name:
    Brian Brown
    The specs that Dan provided from his smog test were taken with the engine loaded on a dyno. You are not going to be able to simulate these readings unless you have a dyno to load the engine. If your car is running well and your catalytic converter is in good condition then your readings should be close to them.
    With the car and exhaust hot your CO should be close to 0%, HC's under 20, and NOX under 200. If you can read CO2, it should be close to 12% and O2 should be low, near 0%.
     

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