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308 QV failed emissions test

Discussion in '308/328' started by elbro, Aug 29, 2009.

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  1. elbro

    elbro Rookie

    Sep 12, 2005
    11
    #1 elbro, Aug 29, 2009
    Had my annual exhaust gas inspection yesterday and failed on the idle CO test by .1%. All other parameters are normal according to state standards (TX) which uses only HC and CO evaluation. Last year when I first got the car, a friend lowered the idle by turning the throttle position adjustment screw, which is supposedly sealed at the factory. Would this make the CO emission high by making it run richer?
    I had run the engine hard right prior to the test, so cats were adequately hot, which allowed it to pass last year.
    Since this is the last year the car has to be "sniffed" I don't want to have to do a lot assuming the engine is not getting damaged otherwise.
    If the adjustment screw isn't the issue, what are some suggestions to pass inspection? any additives help, or hinder?
    Thanks in advance for your engineering expertise.
     
  2. gec

    gec Rookie

    Aug 24, 2009
    28
    Providence
    Full Name:
    Kenny
    #2 gec, Aug 29, 2009
    Hey Bud,

    Do you have the original exhaust on this car? Look at the cats. Has the metal deteriorated and showing some of the ceramic honeycomb? We gotta get you to pass for this final year. How bad were you over? Spark plugs air filter some simple stuff if your just over.
     
  3. eurogt4

    eurogt4 Karting

    Apr 15, 2006
    243
    Sacramento, CA
    Full Name:
    Mike
    #3 eurogt4, Aug 29, 2009
    Throttle postition screw is not where you adjust idle speed. It should be reset according to the book, idle speed is adjusted with the large air adjustment screw. I think it shows this in the manual. Not sure though, if this will make the CO too high, but it won't help.
     
  4. Canut

    Canut Formula Junior

    Aug 11, 2005
    340
    Long Beach, CA
    Full Name:
    Manuel Canut
    #4 Canut, Aug 29, 2009
    My car had the same problem since before I got it. I took it to the shop and the found that the temperature sensor located under the coolant reservoir tank was bad. This sensor was telling the car that it was cold, thus riching the fuel mix. After it was replaced, the car has passed the emissions test with flying colors.
     
  5. elbro

    elbro Rookie

    Sep 12, 2005
    11
    #5 elbro, Aug 30, 2009
    Thanks for the replies and good suggestions. The exhaust system is likely original and intact, at last look. The whole car had an excellent work-over when I bought it 2 years ago, and milage since has been fairly minimal. That may be one of the problems now...I haven't been driving much lately due to a daughter's marriage and very hot weather...
    The car just barely failed the CO emission standard by one-tenth of a percent. The state allows 1.2% CO, and mine was 1.3% The hydrocarbon emissions were really good at speed, on the high side at idle. My impression is the car has always run rich as it smells rich. I noticed last night after my first post that the manual's settings are a lot lower than the state's allowables.

    I will check the filter again. How do you check the temp sensor on the tank?
    Thanks again for the responses.
     
  6. fastradio

    fastradio F1 Rookie
    BANNED Professional Ferrari Technician

    Apr 26, 2006
    3,664
    New England
    Full Name:
    David Feinberg
    #6 fastradio, Aug 30, 2009
    Lowering the idle speed increases emissions. Set the idle speed at the factory specs. Keep your freind away from the car, as there's no reason to tamper with the throttle plate angle adjustment, ever (unless it has been tampered with by the unknowing...)

    Snake oil won't compensate for an otherwise pretty close to specs running engine.

    Ding, ding...ding: We have a winner.

    As the CO is .1% high and the HC is slightly high per the OP, this problem does not apply in this particular situation.

    As your car is slightly out of compliance, and your emissons numbers look pretty good, the "repair" is simple.

    -Set idle speed to factory specs using an accurate tachometer
    -Verify that the air cleaner is clean, which I suspect it is
    -Remove the sealed plug from the fuel distributor
    -With an exhaust gas analyzer, adjust the CO to specs. If all is well with your injectors and ignition components, which based on the information you've provided, you'll have no troble hitting the "State" numbers.

    With all components in good working order...and the mixture set correctly, you should be able to acheive these numbers, pre-cat (if applicable):

    CO<1.2%
    HC<180ppm

    Don't have an exhaust gas analyzer; Find a shop that does...

    Best,
    David
     
  7. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    4,193
    Canada
    #7 moysiuan, Aug 31, 2009
    Seems too simple, but an oil change and new plugs will make enough of the difference you have, especially if you are normally running a bit rich.
     
  8. elbro

    elbro Rookie

    Sep 12, 2005
    11
    #8 elbro, Sep 4, 2009
    All's well that end's well. Had Steve at Scuderia San Antonio tweek everything that needed it. He used exhaust gas analyzer, tweeked the fuel distributor ever so slightly, and got it right on at 1.1% which passed inspection for the last time. Next year is safety inspection only.
    Thanks for all the help and advice.
     

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