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  1. #21

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    Yes it was the vacuum line, but it still pings pretty bad. I'm replacing the knock sensor this weekend and double checking the timing........

    1989 Chevy V1500 Suburban 4X4, long tube headers & xover pipe. w/1985 350 4bbl.
    2002 Silverado 1500 5.3L Ext. Cab
    2005 Wrangler Rubicon 4.0L
    1990 Miata

  2. #22

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    is it still pinging with the timing advance disconnected? If so knock sensor wouldn't be prob as the computer wouldn't be advancing timing at all; it uses the knock sensor as a way of judging if timing has been advanced too far. Double check your base timing first and make sure it's good.
    1986 Chevy G20 Tow Rig - 5.7 TBI conversion
    1978 Mustang II King Cobra Road Racer - Holley 650, MSD 6AL, 5 speed, 10 point Roll Cage, 9" posi, fuel cell, custom interior.

  3. #23

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    Well it wasn't the knock sensor. I retarded the timing to 4 degrees and it is still pinging so bad it is pretty much un driveable. Could it be the computer....... perhaps it jumped timing...... perhaps the knock sensor is not getting any signal to the computer. how would i check that....
    i pulled codes 32, 33, 42........

    1989 Chevy V1500 Suburban 4X4, long tube headers & xover pipe. w/1985 350 4bbl.
    2002 Silverado 1500 5.3L Ext. Cab
    2005 Wrangler Rubicon 4.0L
    1990 Miata

  4. #24

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    I had a few different motor setups in my 1990 suburban over the years. Besides the TBI I had multi-port fuel injection and the final motor had a demon 650 carb on it. If you are still interested in swapping to a carb let me know. It is a fairly easy swap but if you live anywhere that gets cold you will have to spend a little more time warming it up in the morning.

  5. #25

    Default

    Quote Originally Posted by bigbluesub View Post
    Well it wasn't the knock sensor. I retarded the timing to 4 degrees and it is still pinging so bad it is pretty much un driveable. Could it be the computer....... perhaps it jumped timing...... perhaps the knock sensor is not getting any signal to the computer. how would i check that....
    i pulled codes 32, 33, 42........
    It's almost sounding like you may have a computer problem. Does anyone with more experience on this system have any suggestions?

    I can't tell you how to verify that you're computer is getting the knock sensor signal, however you can verify the connection (not real easily) by using an ohm meter, connecting one end to the knock sensor harness, and probing the wire at the computer to make sure you have a closed circuit, and 0 (or minimal) resistance. You'll need some long probes on your meter though, or to hook an extension to it. if the wire is bad or there's a break in the circuit, that could cause your problem. And it's the cheapest thing to check next :/

    Other than that I'm not sure what to tell you. I just want to verify that this is only happening when the electronic timing advance is connected
    1986 Chevy G20 Tow Rig - 5.7 TBI conversion
    1978 Mustang II King Cobra Road Racer - Holley 650, MSD 6AL, 5 speed, 10 point Roll Cage, 9" posi, fuel cell, custom interior.

  6. #26

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    It actually happens both with the EST connected or disconnected. Hopefully tonight I will get some time for Diagnostics. I just subscribed to
    ALLDATAdiy.com. and now have the dealer diagnostic steps for a code 42.

    1989 Chevy V1500 Suburban 4X4, long tube headers & xover pipe. w/1985 350 4bbl.
    2002 Silverado 1500 5.3L Ext. Cab
    2005 Wrangler Rubicon 4.0L
    1990 Miata

  7. #27

    Default

    if it's happening all the time, then you almost have to be running lean, and the timing is likely not an issue. Either computer isn't commanding enough fuel for whatever reason (o2 sensor reading incorrectly, etc), or you have a vacuum leak, bad gasket, or something of the sort. Hopefully the diagnostics procedure you have can put you in the ballpark.
    1986 Chevy G20 Tow Rig - 5.7 TBI conversion
    1978 Mustang II King Cobra Road Racer - Holley 650, MSD 6AL, 5 speed, 10 point Roll Cage, 9" posi, fuel cell, custom interior.

  8. #28

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    Well I am pulling the intake to replace gaskets, i also notice the dist shaft has alot of play so that will be replaced. One thing i noticed, i had my wife bump the starter til it blew my finger out of the #1 spark plug hole (to find TDC) and the rotor is like 3 wires off. I will double check it again tonight. Might have to pull off the front and check the timing chain.
    Fun, Fun, i'm taking my truck to Bloomsburg on the 8th of July........ nothing like a dead-line to make things interesting.......

    1989 Chevy V1500 Suburban 4X4, long tube headers & xover pipe. w/1985 350 4bbl.
    2002 Silverado 1500 5.3L Ext. Cab
    2005 Wrangler Rubicon 4.0L
    1990 Miata

  9. #29

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    Well if you are following my thread "excessive pinging" you will know that i ran out of options and time and had to resort to dropping my truck off at the dealer today. I wish i would have replaced the intake and tbi with a carb months ago, then i wouldnt be having these problems. who knows how much this is going to cost.... I am spending what it would have cost me to switch to a carb. If i switch to a car i suppose i need to get a different distributor set up, is that correct?

    1989 Chevy V1500 Suburban 4X4, long tube headers & xover pipe. w/1985 350 4bbl.
    2002 Silverado 1500 5.3L Ext. Cab
    2005 Wrangler Rubicon 4.0L
    1990 Miata

  10. #30

    Default

    yeah just go to a yard and pick up a good used chevy HEI dist. quickest/easiest to install

    Tough luck on the troubleshooting :/
    1986 Chevy G20 Tow Rig - 5.7 TBI conversion
    1978 Mustang II King Cobra Road Racer - Holley 650, MSD 6AL, 5 speed, 10 point Roll Cage, 9" posi, fuel cell, custom interior.

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