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Engine Question... Bogging under full throttle *Update / Fixed*

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

  1. MudFrog

    MudFrog 1/2 ton status

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    When I press the pedal all the way down my engine will just bog down and sometimes sputter or backfire. When I say bog down it's actually not really bogging down I don't guess. I can hear and feel the RPM's get a lot higher, and I get pulled back in my seat for a split second but the blazer actually loses a little bit of momentum under full throttle. If I just stay on the gas about half way it will get up and go like a 350 with 120k can be expected to do. My timing is at 8* and I just replaced my fuel filter yesterday. I did notice a slight improvement with the new fuel filter, but so many posts on here lead you to believe the fuel filter could be the culprit for what I'm experiencing. Anyone have any ideas?

    Oh yea... I also run the Fuel Injection cleaner stuff about once every 2-3 months, maybe I should rebuild the TBI?
     
  2. TopOff

    TopOff 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    Did you "ask" the computer if there are any codes?

    It sounds like you might be getting too much air in the intake without the computer realizing it.

    I imagine the computer will specify a too lean or too rich condition. Could also be a bad thorttle position sensor.

    Good luck.
     
  3. MudFrog

    MudFrog 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    Yea.. the computer reports a code of 43, and every where I look there is a differen't cause for the 43 code. The manual that my "cheap" code thing came with said it was the O2 sensor so I replaced it and yes it needed to be replaced but it didn't help. The only other symptoms I have is right before the "Check Engine Light" comes on during daily driving. When the engine warms up I can step on the gas and I'll hear a faint pinging, then I'll step on the gas again and the pinging will be a little bit louder the third time I step on the gas the pinging will be quite loud then the check engine light will come on followed by a rank smell /forums/images/icons/crazy.gif. Think maybe the reason I get the code has to do with why the engine has no top end power?
     
  4. txbartman

    txbartman 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    I have a Firebird that did this sort of thing for a bit. Turned out I had dropped a cylinder due to poor plug wires. Wasn't terribly noticeable under normal use, but would be when I got on it. Would jump and then almost sputter. But, i could gradually accelerate. Seemed that the short would only occur under heavy load. I changed out the plugs and wires and it did wonders for it. If you have a 120K miles on it and haven't done that in a while, couldn't hurt anyway.
     
  5. MudFrog

    MudFrog 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    I changed the plugs and wires about 15k ago... I have done some research on the error code 43 and it seems this would almost fit my description to a "T".

    <blockquote><font class="small">In reply to:</font><hr>

    CODE 43

    Trouble Code 43 indicates that there may be a malfunction in the Electronic Spark Control (ESC) circuit.

    ESC is used to sense spark knock (pinging) and retard the timing to eliminate it. A knock sensor (located at the rear of the engine block) sends signals to an ESC module which then signals the ECM that knocking is being detected. The ECM will retard the timing by as much as 20 degrees in 1 degree increments. A loss of knock sensor signal or loss of ground at the ESC module will cause the signal at the ECM to remain high. The ECM will act as if no knock is present, and may possibly result in engine damage, if there is detonation.

    Loss of the ESC signal to the ECM will cause the ECM to constantly retard the timing to its maximum. This results in sluggish performance and a Code 43.


    The conditions for setting this code are:

    Engine is running
    ESC input signal has been low more than 2.23 seconds



    Typical causes for this code include:

    1) Open or shorted knock sensor
    2) Loose knock sensor
    3) Excessive mechanical noise within engine
    4) Improper or incorrectly installed PROM or CALPACK in the ECM or defective ECM
    5) Intermittent open in the EST line to the ignition module


    <hr></blockquote>

    Because I know I deffinitely have sluggish performance.
     
  6. MudFrog

    MudFrog 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    Can someone tell me where the knock sensor is located so I can check to make sure everything is connected. I believe it was next to the block on the passenger side? Just trying to recall from what I read a long time ago.
     
  7. txbartman

    txbartman 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    The knock sensor is in the block, down just above the oil pan, on the passengers side. The ESC plug is on your distributor. It looks like a 4-pin flat trailer plug type of thingy. First try running with this disconnected and see what happens. Reason I say this is that I disconnected mine when I installed my new engine and have never had a problem with it.
     
  8. Thunder

    Thunder 3/4 ton status

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    Re: Engine Question... Bogging under full throttle

    It sounds like you are on the right trail. The knock sensor is on the passenger side described avove. it looks like a oil press sending unit.
    Dont disconnect the Dist wires! That wont work on a TBI truck The ESC unit is located just to the right (the passenger side) of the throttle body. It is a thin square black box with 4 or 5 wires plugged in to it.
     
  9. MudFrog

    MudFrog 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    A little confused... your saying not to disconnect the ESC because it won't work on a TBI... correct?
     
  10. MudFrog

    MudFrog 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    On another note... this afternoon when I went to our other warehouse, before the check engine light came on it seemed like it had plenty of power... a lot more then I'm use to it having (I'm guessing due to the recent timing adjustment and fuel filter change) but once the check engine light came on my power was drastically decreased.
     
  11. txbartman

    txbartman 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    DOOH!! - Yeah. Guess that's right! I was thinking of my lovely non-computer controlled engine. I actually think I got this thread mixed up with another one I was advising on. Sorry bout that. But I would still double check the wires. I know on my firebird I went through 3 sets of plug wires in 3 years (all AC Delco replaced under warranty).
     
  12. MudFrog

    MudFrog 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    I crawled under and sure enough the knock sensor was unplugged. So I plugged it in, but it didn't help. I still get the check engine light and the loss of power etc... It's starting to make me mad /forums/images/icons/smile.gif. Any insight on the other causes listed above?
     
  13. k20

    k20 3/4 ton status

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    Re: Engine Question... Bogging under full throttle

    replace the knock sensor? did mine, and it was the slug, and the engine light, and replaced it, and bada-bing, good as new. Its in the water jacket so u will lose some coolant
     
  14. MudFrog

    MudFrog 1/2 ton status

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    Re: Engine Question... Bogging under full throttle

    Yea.. I'm gonna replace the knock sensor and the ESC. That better get rid of it.
     
  15. MudFrog

    MudFrog 1/2 ton status

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    Ok... I replaced the knock sensor and it FINALLY fixed the problem. This thing has been bugging me for 2 years, I just haven't really looked into it a whole lot untill the past month.

    A funny thing is I was at my softball game Thursday night and I met another guy that has an 89 K5 as well and he is having the same problem.. Maybe this is more common then I thought.

    Thanks for the help everyone!
     

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