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engine light goes on quick, then knocking....UPDATE

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bigblue, Mar 20, 2002.

  1. bigblue

    bigblue 1/2 ton status

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    What could this be...the engine light goes on pretty quick after driving maybe 2-3 minutes...then under load it starts to knock kinda like the lifters or something...anyone have ideas? thanks



    OK, well that is one of the coolest things i have done in a while....i just love when my truck talks to me.... But, I got a code 24
    which is teh vehicle speed senor...now I don't have my speedo hookied up or my wire hooked up to my transfer case...would this
    cause anything like the knocking? The manual says to check the connections at the ecm...

    OK just plugged it back in and the check engine light doesn't go on.. after work I will take the drive home and see if it still knocks....
     
  2. monypit

    monypit Registered Member

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    Re: engine light goes on quick, then knocking....

    what year and is it tbi (fuel injected) or not
     
  3. Chris Demartini

    Chris Demartini 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    <font color=blue>Sounds like it has too much timing, posibly a knock control problem. Jump the A and B terminals and tell me how many times the ligtht flashes
     
  4. bigblue

    bigblue 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    well it is an 87...uh, jump the a and b huh? not really keen on the electronics bit! how do i jump the terminals?
     
  5. bigmack

    bigmack 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    I would check the timing first, also you possibly could have gotten some bad gas that could cause it to make the noise you described (especially under a load).
     
  6. bigblue

    bigblue 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    cool, I will check the timing and put in some decent gas. I was also tod to but some tranny fluid in the engine to clean it out, then change oil...

    thanks,
     
  7. Itali83

    Itali83 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    Your spark knock sensor is probally getting bad. From what I know, I would think that if the sensor is going bad, it'll make the engine light go on, and since it's a spark knock sensor, if it goes bad, I bet you'll get some spark knock. Just my Idea.
    Ben 87 Jimmy
     
  8. Chris Demartini

    Chris Demartini 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    <font color=blue>If you jump the two right terminals on the diagnostic connector under the dash, it will flash which code has been stored in the ECM.
     
  9. arq

    arq 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    could be your knock sensor...

    i'm just guessing, how's the oil pressure???

    ARQ.
     
  10. bigblue

    bigblue 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    Oil pressure is low, i mean definitely at the half way mark then when braking it falls to zero...But the engine still feels like it has plenty of pep....just knocking like hell..I am going to change the sensor

    I am getting a new engine but want to wait till after I pay the TAX MAN before that happens....
     
  11. TopOff

    TopOff 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    before you spend money on replacing parts, get a Haynes manual, and learn how to "ask" the computer what's wrong.

    You "ask" the computer what's wrong by jumping the a &amp; b connectors in the ADL connector.

    The computer will tell you (usually) EXACTLY what's wrong and what part to make sure is connected, or to change out.

    It could be a vaccum leak, a bad knock sensor, a bad ignition module, clogged fuel filter, the list is endless.

    Read the manual.
    Good luck.
     
  12. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    <a target="_blank" href=http://coloradok5.com/forums/showthreaded.php?Cat=&amp;Board=blazer4x4&amp;Number=361732&amp;Search=true&amp;Forum=All_Forums&amp;Words=Blazer_Boy&amp;Match=Username&amp;Searchpage=0&amp;Limit=25&amp;Old=allposts&amp;Main=361659>How to jump A and B</a>
     
  13. JIM88K5

    JIM88K5 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    Check your EGR valve. It's thermostaticly (sp) controlled.
    If it's bad, after warm up it will not function and you may
    (I did) get spark knock (ping).
    Jim
     
  14. RESTORE89

    RESTORE89 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    if you can not figure the jumping thing out you can go to a pepboy etc and get a gm engine code reader with instructions for about $30. that is what i did before i found out a paper clip works real well. also a haynes manual $15 will tell you what the codes mean, and how to change the faulty parts.
    good luck and let us know what the outcome is.
    chris
     
  15. bigblue

    bigblue 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    OK, well that is one of the coolest things i have done in a while....i just love when my truck talks to me.... But, I got a code 24 which is teh vehicle speed senor...now I don't have my speedo hookied up or my wire hooked up to my transfer case...would this cause anything like the knocking? The manual says to check the connections at the ecm...
     
  16. Burbinator

    Burbinator 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    The ECM uses the input from the VSS and other sensors to regulate fuel/spark curves, timing advance, etc.

    If that sensor is out of the loop, the ECM will go into "limp home" mode. In this mode, the ECM uses default values for the faulty (or missing) sensor from the memory table to keep the truck running at a diminished capacity and flags the SES light (check engine).

    Hook your VSS and speedo back up and see if the problem goes away. Why is it disconnected in the first place?
     
  17. bigblue

    bigblue 1/2 ton status

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    Re: engine light goes on quick, then knocking....

    Well I rebuilt my t-case and hooked everything back up except for that...laziness I guess!

    Thanks
     

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