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I was TWICE the legal limit!

Discussion in 'The Garage' started by B_to_C, Oct 28, 2006.

  1. B_to_C

    B_to_C 1/2 ton status Author

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    :(


    HC PPM at 2500RPM: 958.4

    HC PPM at IDLE: 470.0

    LIMIT: 400

    RESULTS: FAIL :(


    "High HC readings are a result of unburned or partially burned fuel."

    I also got this cute little booklet that's titled "my vehicle has FAILED the air care colorado emmisions test...now what do I do?"

    Well according to the manual I need to bring my truck to a qualified mechanic so he can diagnose and fix my problem
    :rolleyes:

    Ok, now for some backstory...

    I swapped this engine from my 1990 Blazer into this 1979 Pickup. In August I had this same engine, with the same exhaust, emmision tested. Those results: (dyno tested instead of stationary tested)

    HC GPM 2.0840

    Limit: 4.0000

    RESULSTS: PASS

    The only things I can think of...

    1. During the engine swap I plugged something in wrong, or didn't plug something in, like a sensor or vacuum line

    2. Something to do with the computer

    3. The engine used to be connected to an auto-tranny, but now it's connected to a manual...I don't really know what this could do, but my current idle RPM is 925
     
  2. 79k20350

    79k20350 3/4 ton status

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    925 seems high for idle... I think im usually at 700+ with a small block.
    How new is the ignition system?
     
  3. B_to_C

    B_to_C 1/2 ton status Author

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    Just to make sure we're all on the same page this is a TBI motor, and I don't think the idle is adjustable (correct me if i'm wrong). As far as spark plugs / wire / dizzy...proabbly 2 or 3 years since I did my last big tune-up on this engine.
     
  4. 79k20350

    79k20350 3/4 ton status

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    Cant say if it should be done or not but i know on my lt1 (which is mpfi) and a way more advanced system i still adjusted the idle with a screw on the tb. I bet it can be done. idk, maybe im crazy but 925 just seems high...
     
  5. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Base idle is adjustable. A quick search will throw up the procedure. My plugs start 'falling off' after 10-12,000 miles. Sounds like you need a bit of maintainence!
     
  6. 79k20350

    79k20350 3/4 ton status

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    depends on the plug too...if he used platniums they may still be ok...But its so cheap its stupid not too...
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Lower idle will make it run dirtier not cleaner. My old 350 used to fail miserably running at 600 rpm, but if I bumped the idle up to 900 it'd pass with flying colors (idle test obviously)

    Rene
     
  8. 79k20350

    79k20350 3/4 ton status

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    hmmm. good to know. My thinking was bringing me to higher rpm = more fuel = more emissons. but i guess when you get that low the engine just may not run as well that low...
     
  9. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    On an injection motor?
     
  10. B_to_C

    B_to_C 1/2 ton status Author

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    Do you really think there could have been such a significant change in just two months due to regular maintanence stuff (technicle terms I know)

    I'm not saying I tihnk otherwise I just want to make sure that's what you're saying.
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    No, mine was carb'd. Still, overlap on the cam gets worse and worse as the R's drop, and even stock cams have some overlap at low idle. My cam was pretty mild (still ran without any lope at 500 rpm) yet there was enough valve overlap to fail me at low idle speeds.

    I took it in and had it hooked to a 4 gas analyzer and the tech showed me I had everything set right on the money as far as the carb went...but as he turned up the idle speed the numbers dropped like crazy.

    Failing on the driven part of the test is a whole 'nother situation though.

    Rene
     
  12. Hossbaby50

    Hossbaby50 3/4 ton status

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    How is your computer hooked up to know it is in gear or park? My TPI will pass AZ & CO emissions when it is in "park" mode. The idle does seem high even for an FI motor which will run at a higher idle.

    Going from an auto to a manual might be part of the problem.

    How far away from your exhaust manifold is your O2 sensor? If it is to far away you may have to have a heated 02 sensor added in. Does your truck currenlty have a cat on it?

    Harley
     
  13. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    It does have a cat, it was new with the exhaust installed about 6 months ago before the previous emissions test. The O2 sensor is in the factory location on the exhaust manifold.

    I've had plugs just start making the motor run chitty all of a sudden. It was like one day it was running fine and the next day it was barely running. Changed the plugs and it was all good.
     
  14. B_to_C

    B_to_C 1/2 ton status Author

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    TTT

    So is the general consensous that I should simply replace my spark plugs and try again? :dunno:

    And what if I fail again?
     
  15. Hossbaby50

    Hossbaby50 3/4 ton status

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    I would change your oxygen sensor as well. Have you changed your oil recently? If not then change it.

    Harley
     
  16. B_to_C

    B_to_C 1/2 ton status Author

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    O2 sensor was changed when the new exhaust was put in... a few months ago. If I remember it was like 20-30 bucks, is it worth it to buy a new one? And the oil was changed 2 weeks ago.
     
  17. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    If it's going into closed loop your O2 sensor is probebly ok(being that it's new, check the wiring though). Check via aldl if it's switching from open to closed loop. Idle should be around 600rpm at 'normal' temps. Are you getting any codes? You can run winaldl and check that it's flipping between rich/lean and look at your O2 count as well as your blm's.
    And as said, does your ecm know when you're in park/N ? Was all that left connected when you did the tranny swap?
    Do your plugs for sure though.
     
  18. B_to_C

    B_to_C 1/2 ton status Author

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    Ok, so I don't have an ALDL connector, should probably take this opportunity to purchase one huh? My roomate, an electrical engineer, has said for nearly two years that he is going to build me one when he "gets the time" but now that it's time for one, looks like I'll have to purchase one. The time crunch I am in is that the truck has to be re-tested within 10 days or I have to repay.

    I don't know how you tell the computer that the truck is in gear or park :what: Is it done through the coloumn or a connector that goes to the 700r4 (that is currently hanging loose in my engine bay) ?

    So I need to have winALDL to determine if the computer is going into closed loop or not?

    I can't check for codes because I do not currently have a cluster plugged in....and won't until next weekend (long story).

    Ok so here's my tentative list for this coming week:

    1. Buy / install some new sparkplugs
    2. Check wiring to O2 sensor
    3. Buy an ALDL cable
    4. Check data on WINALDL and report back here for feedback (because I would have no idea what I'm looking at).

    I also see dyeager was looking at this thread :D any words from "the great one" ?
     
  19. HarryH3

    HarryH3 1 ton status Author

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    Does the Colorado printout after the emissions test list Oxygen? My S-Jimmy failed the emissions test here in Texas miserably. However, the printout showed oxygen at 3.4% in the exhaust. A small leak in ONE header tube (caused by the Edelbrock logo plate that was welded to it :mad: ) was letting enough oxygen into the exhaust stream to make the O2 sensor think that the engine was running too lean. It was telling the ECM to dump in more fuel! :shocked: After I welded the hole the truck passed the test with flying colors. (And Oxygen dropped to about 0.4%)
     
  20. B_to_C

    B_to_C 1/2 ton status Author

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    The Colorado emmisions test measures Hydrocarbons, CO and CO2. I don't know if CO is what you're calling oxygen? but my CO readings were:

    2500RPM: .91%
    IDLE: .67%

    LIMIT 2%
     

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