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Engine pinging when engine is warm... any ideas?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by MudFrog, Jun 18, 2002.

  1. MudFrog

    MudFrog 1/2 ton status

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    When my engine is cold it doesn't ping, whent it's at about 120 degrees it starts to ping just a little bit, when it's at 205 degrees it pings non stop. I just adjusted my timing 2 days ago and it's right on 8 degrees which was the factory specifications. Should I take my timing down to 4 degrees?? Do you have any other ideas as to why it pings when cold but when the engine is warm I can look at the gas pedal and it will ping. It's really starting to tick me off.
     
  2. Thunder

    Thunder 3/4 ton status

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    When you set the timing, Did you disconnect the timing bypass wire? Its a tan and black wire on the firewall by the brake booster. If you time it without disconecting that wire the timing will be way too far advanced.
     
  3. MudFrog

    MudFrog 1/2 ton status

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    Yes I did. Should I disconnect it then turn the truck on or should I turn the truck on then disconnect it. I turned it on then disconnected the bypass wire. I wonder if that might have something to do with it?
     
  4. Thunder

    Thunder 3/4 ton status

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    I always disconnect it with the engine off. Then set the timing. When it is disconnected the "check engine" light comes on. When it is reconnected the light should go off.

    You may also have a problem with the Knock Sensor. Check to see if there are any trouble codes stored. A bad knock sensor will put up a code 42 or 43
     
  5. MudFrog

    MudFrog 1/2 ton status

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    I did have an issue with the knock sensor a while back but replaced it 2 weeks ago, I have not had any error codes listed since I replaced the knock sensor. I'll disconnect the wire with the truck off tonight and try to adjust the timing again. Thanks.
     
  6. MudFrog

    MudFrog 1/2 ton status

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    Ok... I even took it down to 3 degrees and it still pings. Any ideas?
     
  7. Khi5in

    Khi5in Registered Member

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    Assuming your fuel injected try a higher octane fuel and or running injector cleaner through your system. Doesn't sound like a timing problem or it would do it cold too. A cylinder compession test and inspecting the plugs will give you a better idea wich cylinders are getting too much fuel or not enough.
     
  8. MudFrog

    MudFrog 1/2 ton status

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    I'll try some higher octane but I already use 89, and I run the cleaner about every 3 months.
     
  9. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Well sir, you've just said exactly what your problem is...8 degrees. TBI motors are timed at 0 degrees with the wire unplugged and the computer takes over from there.
     
  10. MudFrog

    MudFrog 1/2 ton status

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    Are you sure? My manual and the little sticker under the hood both said 8 degrees. I'll try 0 though.
     
  11. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Really?! Usually they some crap about disconnecting that wire comming out of a harness by the bulkhead, yada yada. They all looked the same, 0 degrees. It is the original TBI motor with the little biddy distributor, right?
     
  12. MudFrog

    MudFrog 1/2 ton status

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    The guy I bought it from told me it was replaced but I don't beleive him. Anyone know how I can tell if it is the original? But yea it says 8 degrees on the sticker.. I'll probably still try 0 degrees.
     
  13. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Hmm, it may have had some battle damage and had an older front clip put in. The bottom of the sitcker on there should say something about conforming to emissions standards and then the year. Regardless, 0 degrees is what it wants and the computer determines where to do from there. I'd change the knock sensor too because it should have picked up on the pinging. Good Luck
     
  14. MudFrog

    MudFrog 1/2 ton status

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    I just replaced the knock sensor though. I was also wondering why it didn't pick it up. I did finally get a check engine light today when I was driving it so I need to see what the error code is.
     
  15. MudFrog

    MudFrog 1/2 ton status

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    Ok... so I was reading around on some other sites, and basically we set the timing to 0 (according to you) and the knock sensor will adjust it as needed (according to other sites). Will the knock sensor ever advance the timing or does it just retard it?
     
  16. TopOff

    TopOff 1/2 ton status

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    The knock sensor ... senses knock. The computer then adjusts (retards timing) until knock goes away.

    The computer will advance the timing (depending on programming) given certain conditions, RPM, engine temp, 02 sensor, fuel, and knock sensor.

    Check your codes, and see what needs to be replaced.

    You should also get a code if the base timing is wrong.

    Good luck.
     

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