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Chk Engine & pinging 1991 5.7

Discussion in 'Chevy Trucks' started by kbsnow, Jan 22, 2010.

  1. kbsnow

    kbsnow Senior Member
    from Chicago
    Messages: 146

    I have 172,000 miles, and it runs like a champ except for the issue above. It burns no oil, and the chk engine light only comes on if I really womp on the accelerator while driving. If I gradually accelorate the light will not come on. Under hard acceloration when the light comes on it also starts to ping a bit. Once I shut the engine off, the light does not come on when restarting. I don't have any testing equipment to read any codes.

    Any ideas/suggestions?
     
  2. jb1390

    jb1390 Senior Member
    Messages: 710

    Paper clip

    For OBD1, you don't need a reader, all you need is a paper clip. Here is a link on how to use a paper clip to get the codes. You short out the upper right two pins and watch the check engine light-each code will flash 3 times. Post back what the codes are when you get them. (code 12 will flash the CEL one long, pause, two long, (long pause), and so forth)


    http://images.google.com/imgres?img...lip&hl=en&sa=N&um=1&ei=LxpaS9j7PIrmlAeb69D2BA
     
  3. Evanbrendel

    Evanbrendel Senior Member
    Messages: 181

    pinging as in detonation? maybe carbon build up if thats what you mean by pinging. maybe to much timing also.
     
  4. Plowfixguys

    Plowfixguys Senior Member
    Messages: 222

    Make sure the EGR valve is working also. Once you find the codes the rest will be easy.
     
  5. kbsnow

    kbsnow Senior Member
    from Chicago
    Messages: 146

    I hope to get to it this weekend...I'll report back with my findings
     
  6. kbsnow

    kbsnow Senior Member
    from Chicago
    Messages: 146

    OK, I jumped A n B, and here is what I come up with. When I first turn the key the chk eng light flashes, then a pause, then 2 flashes, then a pause then 1 flash. According to the code chart you provided, there is no code 12, so does this mean it is 21, which is the TPS sensor?\


    I GOT THE CODE...another site stated that 12 will flash 3 times, then the REAL CODE will flash 3 times, then the 12 again and it repeats. SO, I am getting code 43 which states The ECM did not detect a knock signal during near wide open throttle, or knock sensor voltage was high or low. Does this mean I need a new knock sensor?
     
    Last edited: Jan 25, 2010
  7. RichG53

    RichG53 PlowSite.com Addict
    Messages: 1,135

    Could be your Knock sensor......
     
  8. jb1390

    jb1390 Senior Member
    Messages: 710

    Could be the knock sensor, also check the wiring going to the knock sensor, and the plug itself for corrosion. The knock sensor is located on the passenger side of the engine block, you can see it through the wheel well if your splash guard is taken off. You can also get at it from underneath the truck. If you do decide to change it, make sure the truck is COLD and the radiator cap is on, because the knock sensor also doubles as a coolant plug. If you change them out fast, you shouldn't lose much coolant (I lost a few drops). I don't think the sensor is very expensive so it is probably a good place to start. When was the last time you did a tune up?
     
  9. kbsnow

    kbsnow Senior Member
    from Chicago
    Messages: 146

    Well its due for new plugs which I bought, just never installed them. I'm glad you mentioned it is a coolant plug too, as it is 20 deg now and gonna get colder this week. The truck don't fit in the garage so all the work is done in my alley. since the light only comes on when I womp on it (very rare), and resets when I shut the truck off, I may wait until it stays in the 40's or 50's. A new sensor is less than $30.