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Thread: Failed Emissions Test

  1. #1
    Junior Member
    Join Date:  Jun 2011

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    Failed Emissions Test

    I was hoping I could get some help on a failed emissions test in Colorado. The car isnít driven that often but runs great when I do take it out with no issues. The car has a Stage II engine I installed 5 years ago and just missed passing. At idle the limits for HC are 220.0 PPM and the reading was 227.0 PPM. Here are the emission test results:

    Emissions.JPG

    Any ideas on a tweak to drop the HC. Thanks.

  2. #2
    Senior Member NckT's Avatar
    Join Date:  Jun 2011

    Location:  Yorkshire UK

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    My VIN:    No. 4068

    For the sake of 7 HC ppm, first off check that the air filter is clean, or fit a new one just for the test. I'd also fill the tank with fresh fuel if you don't drive it much, and take it for a good run in a lower gear on a motorway to get the catalytic converter nice and hot.

    The same happened to me on last year's emission test as I hadn't driven it much the previous year. It was just stale fuel. The HC in my case went from 980ppm ish to 250ish (without catalytic converters on as this is legal in the UK)

    If it's a Stage 2 that has the 'higher lift more overlap' type camshaft, you could also temporary increase the idle revs 'temporarily' to 1000rpm to pass.

    If the above quick fix doesn't work then it'll be time to check spark plugs/ fueling etc etc etc

    Good luck
    Last edited by NckT; 09-11-2017 at 01:01 PM.
    RIP Rob van de Veer Top bloke

    I say Sir, I must be mad, one loves fixing K-Jet !

    Make sure there's plenty in the tank for the weekend chaps....

  3. #3
    Senior Member vwdmc16's Avatar
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    Quote Originally Posted by NckT View Post

    ...you could also temporary increase the idle revs 'temporarily' to 1000rpm to pass.
    ..


    Idle speed is one of the test parameters, it has to be within 50 RPMs of the factory 775 RPMs in many places.

  4. #4
    Senior Member NckT's Avatar
    Join Date:  Jun 2011

    Location:  Yorkshire UK

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    Quote Originally Posted by vwdmc16 View Post
    Idle speed is one of the test parameters, it has to be within 50 RPMs of the factory 775 RPMs in many places.
    I didn't know that. Must be an American test specification.

    I did note on the attached image that the limits spec was 1350rpm so I was going on that.
    RIP Rob van de Veer Top bloke

    I say Sir, I must be mad, one loves fixing K-Jet !

    Make sure there's plenty in the tank for the weekend chaps....

  5. #5
    Delorean Guru
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    I agree with the stale fuel. That is probably all you need to do, burn up what's in the tank and refill with fresh before the next test. Get the motor good and hot before you go for testing. If that doesn't work the next thing to check would be any vacuum leaks.
    David Teitelbaum

  6. #6
    Junior Member
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    Thanks for the fast responses. My first though was bad fuel so I drained the tank and filled it up with fresh gas yesterday. I'll put some miles on it and try retesting later this week. Thanks again.

  7. #7
    Senior Member Chris 16409's Avatar
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    Location:  Fresno, CA.

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    I've never seen Hydrocarbons over 200 ppm. I've got a Spec 1 exhaust and my HC values were around 50. Something seems off to blow over 200.
    Chris Miles

    For Better or Worse I own a DeLorean!
    1983 Grey Manual, VIN #16409, Fresno, California

  8. #8
    Senior Member DMCVegas's Avatar
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    Quote Originally Posted by Chris 16409 View Post
    I've never seen Hydrocarbons over 200 ppm. I've got a Spec 1 exhaust and my HC values were around 50. Something seems off to blow over 200.
    I have. Clogged #5 injector resulting in an incomplete burn, and garbage spark plug wires that leak.
    Robert

    Board Member, DeLorean Owners Association



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