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Emissions ???

Discussion in 'The Garage' started by hardcore_rob, Feb 4, 2004.

  1. hardcore_rob

    hardcore_rob 1/2 ton status

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    So I got my emmisions done and failed because of high HC's. The sheet says that it is cause by gas not combusting fully. They said that there was also a misfire. I changed the wires and plugs, cleaned the carb and added fuel additive. Is there anything else I can do to make sure i pass my re-test???

    rob
     
  2. Dandwg

    Dandwg 1/2 ton status

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    add "sea foam" to your gas. You can get it from Napa, I heard it works wonders /forums/images/graemlins/cool.gif
     
  3. Goober

    Goober 1/2 ton status

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    Is that on your '81?

    <ul type="square">
    [*]Make sure you don't have any vacuum leaks.

    [*]You have a Quadrajet, right? Make sure the idle mixture is set properly. I've seen folks try to lean out the mixture screws to try and reduce emissions but when you lean it out too much then the air/fuel mixture won't ignite in the cylinder and the raw fuel gets dumped out the tailpipe. Smells bad and creates a "miss" at idle.

    [*]Doublecheck your firing order: 1 8 4 3 6 5 7 2. MAKE SURE 5 &amp; 7 ARE ON THE RIGHT PLUG!

    [/list]


    Have fun. /forums/images/graemlins/thumb.gif
     
  4. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Ok so its an 81 ( had to look it up by your name ) , is it stock? My simple formula for emissions is to just change every filter, plug/wires, cap/rotor/, time the engine to spec and adjust carb for best idle and set idle speed. I never actually have the addirive in tank during test, use it to run the carb clean then gas up with 93 octane. I have 125.000 on mine and blow clean /forums/images/graemlins/thumb.gif
     
  5. hardcore_rob

    hardcore_rob 1/2 ton status

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    [ QUOTE ]
    Is that on your '81?

    <ul type="square">
    [*]Make sure you don't have any vacuum leaks.

    [*]You have a Quadrajet, right? Make sure the idle mixture is set properly. I've seen folks try to lean out the mixture screws to try and reduce emissions but when you lean it out too much then the air/fuel mixture won't ignite in the cylinder and the raw fuel gets dumped out the tailpipe. Smells bad and creates a "miss" at idle.

    [*]Doublecheck your firing order: 1 8 4 3 6 5 7 2. MAKE SURE 5 &amp; 7 ARE ON THE RIGHT PLUG!

    [/list]


    Have fun. /forums/images/graemlins/thumb.gif

    [/ QUOTE ]


    yes the 81.

    Passed with flying colors last year
    the HC went up enormously this year. the plugs and wires were pretty old. The wires were breaking as i was pulling them off. Not good. Not real sure when they were changed last.

    the emissions guy said that it was very lean. more than it should be. I have never adjusted that. where is the adjustment on the quadrajet and any tips would be greatly appreciated.

    Pretty sure I dont have any vaccum leaks.
     
  6. hardcore_rob

    hardcore_rob 1/2 ton status

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    has new air filter, oil change, oil filter, pcv valve. Probably should get a new fuel filter as well. I will take a look at the cap.
     
  7. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    There is 2 screws on the front and bottom of you carb. It takes a special tool to turn them though.
     
  8. 4by4bygod

    4by4bygod 1/2 ton status

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    Hi All!

    One thing that's helped me pass the smog test is to get the engine good and hot just before testing. Take it on the freeway for a few miles, don't rely on 35 -45 mph cruising to do it.

    If you take a lot of short trips, the engine never cooks off the carbon build up in the combustion chambers. All of the other suggestions are great, I used to struggle with an 84 that had the quadra junk and 500 miles of vac lines, I "stepped up" to an 87 TBI, which eliminates much of what could cause it to flunk an emissions test. When I did flunk once beacause of high HC's in the 84, getting it hot enough solved the problem.

    Don't bother with sea foam.. all it is is kerosene, which doesn't combust, and as a result, creates more carbon build up. good luck. /forums/images/graemlins/k5.gif /forums/images/graemlins/usaflag.gif
    Tom
     
  9. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    [ QUOTE ]
    One thing that's helped me pass the smog test is to get the engine good and hot just before testing. Take it on the freeway for a few miles, don't rely on 35 -45 mph cruising to do it.



    [/ QUOTE ]

    Thats to get the cat good and hot.

    Adjusting the Idle mixture screws will do nothing in the ASM mode (dyno) because your not idling, your loading it down. The only time that will matter is on the Two Speed Idle Test.

    As for the HC problem, check for a misfire, or as stated above, if its set too lean it will actually run rich.
     
  10. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    [ QUOTE ]
    Hi All!

    One thing that's helped me pass the smog test is to get the engine good and hot just before testing. Take it on the freeway for a few miles, don't rely on 35 -45 mph cruising to do it.

    If you take a lot of short trips, the engine never cooks off the carbon build up in the combustion chambers. All of the other suggestions are great, I used to struggle with an 84 that had the quadra junk and 500 miles of vac lines, I "stepped up" to an 87 TBI, which eliminates much of what could cause it to flunk an emissions test. When I did flunk once beacause of high HC's in the 84, getting it hot enough solved the problem.

    Don't bother with sea foam.. all it is is kerosene, which doesn't combust, and as a result, creates more carbon build up. good luck. /forums/images/graemlins/k5.gif /forums/images/graemlins/usaflag.gif
    Tom

    [/ QUOTE ]
     
  11. hardcore_rob

    hardcore_rob 1/2 ton status

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    Thanks for all the tips, I took it back this morning with new plugs and wires, and a very clean carb. Passed with flying colors.

    rob
     

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