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emmisions help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dheavychevy38, Oct 20, 2004.

  1. dheavychevy38

    dheavychevy38 1/2 ton status Premium Member

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    i have a 89 k5 with a tbi 5.7 th350 trans the problem is i can't get it to pass. /forums/images/graemlins/confused.gif i put a new o2 sensor in it cause the old one was junk and throwing codes i put a new cat behind the drivers door
    and the oil was just changed.
    the problem is it is running to rich the spec is 220 and it blew a 721 /forums/images/graemlins/mad.gif any help would be great i only have 1 more try


    new stuff \
    1 new cat
    2 new o2
    3 oil change less than 100 miles
    4 tune up
    /forums/images/graemlins/1zhelp.gif
     
  2. 1979jimmy350

    1979jimmy350 1/2 ton status

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    how do the plugs look?
     
  3. dheavychevy38

    dheavychevy38 1/2 ton status Premium Member

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    don't know i will have to yank one to check it out /forums/images/graemlins/thinking.gif

    the truck runs kick a$$ /forums/images/graemlins/screwy.gif by the way the headers work good /forums/images/graemlins/peace.gif
     
  4. 1979jimmy350

    1979jimmy350 1/2 ton status

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    it would be best to pull them all out and line them up in order and compare. Then post a pic if possible or just describe the color that they are. This will tell alot about what is going on in the engine
     
  5. dheavychevy38

    dheavychevy38 1/2 ton status Premium Member

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    right know i am at work so i will pull them out and check them in a couple of minutes /forums/images/graemlins/whistling.gif don't know how to post pics /forums/images/graemlins/dunno.gif
     
  6. sickquad

    sickquad 1/2 ton status

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    A mechanic told me once that a lower thermostat would help. Becuase the gas they are looking for in the emissions test is formed in your cylinder head, and the hotter you cylinder head is the more of this gas is created. So a marginal motor can be helped with a cooler thermostat. Don't know if this is correct or not.

    -Chris
     
  7. BlueBlazer

    BlueBlazer 1/2 ton status

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    Sounds like his HC are high, your fix would only help Nox but make HC even worse.
     
  8. tx_sub

    tx_sub 1/2 ton status

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    run the truck on the highway for a several miles to blow out any crap in the cylinders. plus it gets everything up to operating temp.

    does anyone know if changing the o-tang of fuel changes emissions?

    anyway, good luck, i've spent thousands of dollars to get my 91 350 tbi /forums/images/graemlins/burb.gif to pass a couple of times
     
  9. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    Sounds like his HC are high, your fix would only help Nox but make HC even worse.

    [/ QUOTE ]

    Illinois doesn't fail people on NOx. That figure is on your test sheet but it's not a testable substance, it's for reference only.

    Get the hottest thermostat you can find, drive it around and get it as hot as you can, replace your plugs, and check your ignition timing. You WILL pass.
     
  10. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    IL is prolly totally differrent then CA but....

    Can you post the limit and your readings?

    Sound like you should check the timing.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    *IF* plugs/wires/cap/rotor haven't been checked/inspected, that should be one of your first things to inspect.

    I personally won't change a cap and rotor if they are fine, might clean up the contacts, but plugs and wires are pretty hard to tell unless the engine runs rough enough to isolate the bad cylinders, then you can pinpoint the problem. If plugs and wires are OLD, then just replace them.

    Is it still throwing codes? Old O2 was probably junk because it's been running too rich for too long and poisoned it. Vehicles WILL run killer with horrible fuel mix, I know, I was getting 10MPG in a car that should have been getting 20+. Running full rich will do that to you.
     
  12. dheavychevy38

    dheavychevy38 1/2 ton status Premium Member

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    if you go by the plugs the truck is running lean they have been in there for 1 month.
    i don't think the cat is doing the job inlet temp is 300 and the exit is 150
    i had the truck good and hot when i took it the only thing other than the cat is the timeing still need to check
     
  13. 1979jimmy350

    1979jimmy350 1/2 ton status

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    if you are running real lean you will still have excess HC because the combustion is inefficent if you make it run closer to what it should be it should reduce the HC levels
     
  14. dheavychevy38

    dheavychevy38 1/2 ton status Premium Member

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    but how can i change it it is tbi not adjust on that bad boy /forums/images/graemlins/thinking.gif bfh might fix it /forums/images/graemlins/weld.gif /forums/images/graemlins/grind.gif /forums/images/graemlins/hack.gif /forums/images/graemlins/thumb.gif
     
  15. dheavychevy38

    dheavychevy38 1/2 ton status Premium Member

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    ok heres the sheet

    HC standards 220 MINE 721 /forums/images/graemlins/yikes.gif
    CO standards 1.2 MINE 8.1 /forums/images/graemlins/yikes.gif /forums/images/graemlins/yikes.gif

    these are the specs on the sheet they gave me
     
  16. 1979jimmy350

    1979jimmy350 1/2 ton status

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    it could be the fuel pressure regulator. you could have leaky injectors. take off you air cleaner and watch the injectors are they dripping or spraying a fine mist? to test the fuel pressure you screw a pressure gague on to the teat port i think tbi should be around 7.5 psi
     
  17. dheavychevy38

    dheavychevy38 1/2 ton status Premium Member

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    i will check in about 1/2 hour when i get off work and let you guys know
     
  18. sickquad

    sickquad 1/2 ton status

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    As far as fuel goes, a lower octane combusts with less pressure which is why high compression motors run super. Now, does that mean you can real lower octane gas, if you can find it, and it will more completely combust, therefore less crap out of your tailpipe?

    Just thought about that today while I was staring at the wall at work. Anybody know if that is true?

    -Chris
     
  19. 1979jimmy350

    1979jimmy350 1/2 ton status

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    yes it is i had to get a 1993 1500 5.7 to pass the first time around on 87 it fail the next time around on 93 it failed even worse the CO levels were way higher then the 87 and The HC was .03 points lower the third try with a new CAT and 87 passed no problem
     
  20. dheavychevy38

    dheavychevy38 1/2 ton status Premium Member

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    ok so i moved the cat forward and it seems to be working judgeing by the temp gun /forums/images/graemlins/waytogo.gif but the coolant sensor flashed a code so i will switch that in the morning and go test.

    so over all it has been a long day
    list of broken stuff
    1 spark plug /forums/images/graemlins/whistling.gif
    2 heater core went out on the way home /forums/images/graemlins/angryfire.gif it's been one of those days
     

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