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HELP!!! 91 K5 failed emissions by 22 hydrocarbons?????

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by CiceroK5, Jul 8, 2003.

  1. CiceroK5

    CiceroK5 Registered Member

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    I think my computer might be shot. If i beat on my truck on the highway the service engine soon light comes on and it runs like crap. if the light goes off it runs fine. the emissions dude was beating on the truck and it happened, or atleast i think. How can i check my puter or is that even my problem? im supposed to get a 160 and i got a 188 on the hydrocarbons, anybody know what i need?
     
  2. rampage

    rampage 1/2 ton status

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    Your computer is fine, especially since your engine light is coming on. First thing you need to do is find out what code your computer is giving (do a search on this). It sounds like you need to give your truck a little TLC and give it a tune-up. Plugs, wires, cap/rotor, air/fuel filter,O2 sensor, EGR valve should be replaced. If I remember correctly, being high in hydrocarbons means unburnt fuel. After doing your tune-up I suggest having your truck pre-tested. They just hook it up to the sniffer, the results don't go to the DMV.
     
  3. k20

    k20 3/4 ton status

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    you can pull the codes by makin a paperclip into a U shape, and then stickin the two prongs into the top 2 right ports on the prom connector on the bottom of the dash, its to the left of the column under the dash. While holding the paperclip in, switch the truck to acc, and the check engine light will flash the code, it will flash, then go away, then give 2 quick flashes, that is code 12, it will flash that 3 times, then it will flash any stored codes, then 12 3 more times. Whatever the stored codes are, is part of what is wrong. If you dont have the definitions for the codes, then post up the # and answers will follow.
     
  4. K5Jimmy

    K5Jimmy 1/2 ton status

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    ....all of the above, PLUS...make sure you have a 195* thermostat...my 89 failed and the tstat fixed it....all this is After I did the EGR, plugs, wires, cap, rotor...and Bosch O2 which was Bad right outta the box...Buy a Delco O2 and save yourself some money...I'll Never buy a Bosch O2 as long as I live....Plugs, etc seem to be ok tho.... /forums/images/graemlins/thumb.gif
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    SET YOUR IGNITION TIMING when you're done with the tuneup too!
     
  6. rampage

    rampage 1/2 ton status

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    On my 89 you're told not to adjust the timing and I think it's controlled by the computer too. So I'm sure the 91 is the same.
     
  7. JeremyK5

    JeremyK5 1/2 ton status Premium Member

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    I thought you still had to set the base timing?
     
  8. HarryH3

    HarryH3 1 ton status Author

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    [ QUOTE ]
    On my 89 you're told not to adjust the timing and I think it's controlled by the computer too.

    [/ QUOTE ]

    You have been misinformed. /forums/images/graemlins/eek.gif There's a connector under the hood that needs to be disconnected, then you set the timing. Then reconnect the connector again when you're done. The computer adjusts the timing on the fly, but it doesn't have a reference signal, so it doesn't know where top-dead-center is. /forums/images/graemlins/shocked.gif It runs on the assumption that you have adjusted the base timing properly.
     
  9. CiceroK5

    CiceroK5 Registered Member

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    I had the tuneup 2 months ago, covered everything. Then 2 weeks ago i had a whole new exhaust put on, even a new cat so WTF!!!!I did the paper clip test and i pulled this
    3 times it flashed
    1 then 2
    3 times it flashed
    1 then 3
    3 times it flashed
    2 then 4
    3 times it flashed
    4 the 4
    Before i got the "code 12" (1 then 3), it flashed a code of 1 then 2?? whats that mean i did this several times. but after i got the code 12 i t flashed a 2-4 and a 4-4. 2 Flashes then 4 etc. Any help would be greatly appreciated.
     
  10. rampage

    rampage 1/2 ton status

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    I guess you do learn something new every day /forums/images/graemlins/thumb.gif

    In the service manual code 13 indicates that there's an open in the O2 sensor circuit. Code 44 indicates a short in the O2 sensor or the O2 sensor is running lean error. Code 24 indicates VSS loss of signal (vehicle speed sensor).
    When you had your new exhaust put on did that include headers (without a provision for an O2 sensor)? Do you know when you started getting the check engine light? Was it after the tune-up or after the new exhaust?
    I'm going to place my money on a bad O2 sensor. Some people swear that one brand will give problems, but I don't remember if it's Bosch, AC Delco or who. Someone else remember?
     

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