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Thread: failed smog

  1. #1
    Senior Member glockworks21's Avatar
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    failed smog

    Now that ive done all the vod work set dwell and had the idle surge under conrtrol the car is running as smooth as it ever has and if failed smog as a gross polluter.
    should I just lean the fuel mixture out so it runs like s*** and re test?
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  2. #2
    Senior Member AugustneverEnds's Avatar
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    Was the test conducted with your car warmed up? What's your oxygen sensor's story? You might be running in open loop. That is where I would start.

    While I'm here thinking, how is your catalytic converter? It can look fine on the outside but be completely shot inside.
    Nick A.

    1988 BMW 325is
    1982 DeLorean DMC-12
    1989 Jaguar XJ6

  3. #3
    Senior Member glockworks21's Avatar
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    I cant remove o2. I may try again this weekend. Im going to take axle out to get more room. the timing is at 13deg it was 15 last time when it passed. It was fully warmed up when i got it there. I had a torch on the base of that o2 sensor when i tried removing a couple weeks ago. I wonder if that damaged it. I called 4 different muffler shops today to see if someone would break that sensor free and nobody wants to touch it. Im going to set the timing back to 15 and lean out the mixture and see if It will pass unless someone else has another suggestion.


    Or im just going to move out of this state..

  4. #4
    absotively posilutely bytes311's Avatar
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    Do you hear the frequency valve buzzing with the motor running?

  5. #5
    Senior Member
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    California is TOUGH on emissions. You may need a tune-up, plugs, wires, valve adjustment, O2 sensor, air filter, and mixture adjustment. Just tweaking things doesn't always get it done.
    David Teitelbaum

  6. #6
    Senior Member mhanch's Avatar
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    Quote Originally Posted by AugustneverEnds View Post
    Was the test conducted with your car warmed up? What's your oxygen sensor's story? You might be running in open loop. That is where I would start.

    While I'm here thinking, how is your catalytic converter? It can look fine on the outside but be completely shot inside.
    Can you replace just the catalytic Converter or is a whole new exhaust the best bet?

  7. #7
    Senior Member Rich's Avatar
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    Quote Originally Posted by glockworks21 View Post
    Now that ive done all the vod work set dwell and had the idle surge under conrtrol the car is running as smooth as it ever has and if failed smog as a gross polluter.
    should I just lean the fuel mixture out so it runs like s*** and re test?
    No, don?t lean it out til it runs poorly.

    As others say it could be the cat or the O2 sensor or both. Or something more. Try to keep your cat til you rule out other issues.

    Did this car pass CA smog before? How recently?

    Did your smog tech suggest anything? Failing at over 2X on NOx and HC isn?t even close to success as you can tell.

    Step 1 is getting your system into closed loop - where the dwell will regularly cycle up and down a few degrees like it should. Getting a known good 02 sensor into it may be critical. Somebody can get yours out of the manifold. Be sure the replacement gets a little antiseize treatment.

    Send a PM to forum user vwdmc16. He?s a long-time D owner in your area who will know which shops can assist with sensor removal and sorting your emissions or he may offer to take it on at his shop if it is so equipped.

    Just know that a stock D powertrain can meet CA smog every time once the components are humming like they should.
    March '81, 5-speed, black interior

  8. #8
    Administrator Ron's Avatar
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    I'd suggest checking the dwell. (If you haven't since the O2 sensor met the torch ;-)

  9. #9
    Senior Member glockworks21's Avatar
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    Quote Originally Posted by Ron View Post
    I'd suggest checking the dwell. (If you haven't since the O2 sensor met the torch ;-)


    Dwell was way high. 20s to 40s on 8cyl mode... dont know what made that change. Would that be enough to make it fail?

    Yes it passed smog 2 years ago after I adjusted timing. since then ive done plugs wires all vac line vod included fuel lines ect. Frequency valve is humming all the time.

    I just let it heat up and checked dwell. There was a point after it was hot and swinging high that i made adjustments and it stopped swinging for about a minute or so.. then it started up again. I need to get that o2 sensor out....

  10. #10
    Senior Member Rich's Avatar
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    Quote Originally Posted by glockworks21 View Post
    I just let it heat up and checked dwell. There was a point after it was hot and swinging high that i made adjustments and it stopped swinging for about a minute or so.. then it started up again. I need to get that o2 sensor out....
    Yes, you do.

    Check out post #7 in this thread for possible local support on that.
    March '81, 5-speed, black interior

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