Smog test numbers -- Comments needed! | FerrariChat
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Smog test numbers -- Comments needed!

Discussion in 'Technical Q&A' started by Geoman54, Jul 14, 2007.

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  1. Geoman54

    Geoman54 Karting

    Jun 12, 2007
    50
    Northern California
    Full Name:
    Michael McLaughlin
    #1 Geoman54, Jul 14, 2007
    Five variables are measured here in California. I've listed them at the 15mph and 25mph roller test on my '85 Mondial. The engine has 71K on it, and is bone stock with the exception of a K&N air filter and the Magnaflow Metal-substrate single CAT I just fitted. I squeaked through on one of these variables (HC at 15 mph) and was hoping some of you might be able to add a couple of comments. So:

    @15mph %CO2 was 13.7
    %O2 was 1.0
    HC(ppm) was 121 (max allowed of 124)
    CO(%) was .32 (max allowed of .78)
    NO (ppm) was 189 (max allowed of 1089)

    @25mph %CO2 was 13.8
    %O2 was .90
    HC was 65 (max allowed of 99)
    CO was .26 (max allowed of .58)
    NO was 187 (max allowed of 919)

    Prior to the official test I had fiddled a bit with the 3mm adjuster on the fuel distributor. If I went too lean it seemed the Lambda circuit would kick in and I would experience a "hunt" at idle with a dwell time of maybe 2-3 seconds. As soon as I put a tad bit (1/8 turn) more richeness in it -- it immediately stabilized and I set the warm idle speed right at a steady 1000 rpm ,which is the spec +/- 100 rpm according to the emissions sticker in the engine compartment.

    I had noticed a broken plastic nipple at one of the two little round canisters that sit above the main rectangular charcoal canister. Not sure what effect that may have overall.

    regards,

    Mike M.
     
  2. Private_Joker

    Private_Joker Formula Junior

    May 2, 2007
    271
    718 and 978
    Full Name:
    Tom
    #2 Private_Joker, Jul 14, 2007
    If it's connected to the evap system you'll put out more HC's, but not through the tailpipe. On an OBDII car it may throw a check engine light during a self check of the evap system and gas tank, noticing the leak to atmosphere.
     
  3. oldcoin

    oldcoin Formula Junior

    May 1, 2006
    258
    Reno NV
    Full Name:
    Tony Mitchell
    #3 oldcoin, Jul 14, 2007
    Next time you have the somg test done, change the oil before the test. This will often reduce the HC reading. Out side to that, your test results look good and in line with what I have seen
     
  4. KENCO

    KENCO Formula 3

    Nov 1, 2006
    2,396
    FL
    Full Name:
    KJG
    #4 KENCO, Jul 14, 2007
    Move to Florida. No tests here.............not even an inspection.
     
  5. wolftalk

    wolftalk Formula Junior

    Jan 27, 2004
    367
    san franciso area
    Full Name:
    phil
    #5 wolftalk, Jul 15, 2007
    a little idle hunting is what they normally do. If it's excessive, it's often the O2 sensor. If you've richened it beyond the ability of the frequency valve to compensate, that gets rid of idle hunt, but also negates the purpose of the lambda/emissions function.

    with the engine warm, tap into the output of the O2 sensor to see voltage you are getting out of it.

    just for reference, my 50K miles '89 328 produced these numbers last november (it has a generic $20 O2 sensor in it):

    15mph
    -------
    %CO2 - 14.8
    %O2 - 0.6
    HCppm - 7
    %CO - 0.01
    NOppm - 134

    25mph
    -------
    %CO2 - 14.9
    %O2 - 0.4
    HCppm - 6
    %CO - 0.00
    NOppm - 125

    a somewhat crude but reasonably effective way of setting the base fuel mixture is to adjust it on a warm engine to get approx 0.5V out of the O2 sensor. That allows the frequency valve to tweak it about the same amount in either direction.

    Enrichment at cold operation and at WOT is mainly the job of the WUR, though the frequency valve is operating at a fixed duty cycle that is slightly rich also.
     

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