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Thread: What should I do about my main spark table?

  1. #1
    Fuel Injected!
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    What should I do about my main spark table?

    79 Jeep, AMC 401, 6197427, 454 throttle body, $OE, Tunerpro RT, Iron heads, 91 octane fuel, ~9.5:1 compression, forged pistons, Mechanical advance is welded, vacuum advance removed, .

    I have my computer controlling my timing and it seems to be working correctly. I have installed a 454 knock sensor into the side of my block and wired it up. I do not get a check engine light for my KS unless I unhook it so I assume it is working correctly. My Jeep runs pretty well but is a bit gutless toward the top end.

    Took it out for a run today, and logged my data. I had no knock retard ANYWHERE in my history tables. Literally, it was all 0's. I also did not hear any knocking/pinging while I was driving it. This made me assume I have no knock and intended to add 2 to 4 degrees to my table when I got home. But as I looked at my average timing table I see there were times when I was at almost 44 degrees! (here's my history table from TunerPro)
    Spark history.jpg
    If I compare the history table to the main spark table, the truck seems to be doing what it is supposed to: (here is my main spark table from my BIN)
    main spart table.jpg

    So I'm stuck. Do I go after my knock sensor assuming it is not working? Do I just assume, with 91 octane it will not knock, and take some timing out of it and see how it performs? Or do I keep adding spark until I get problems? Or am I missing something all together?

  2. #2
    Super Moderator dave w's Avatar
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    There is the option of temporarily disabling the Knock Sensor to compare the history tables, with knock sensor and without knock sensor.

    Possibly tap on the block, near the knock sensor, with a small hammer (vehicle in park at or near idle RPM's) and see if the history table records any knock retard.

    It would be a good plan to look at knock counts in the exported data log, aka .csv Excel spreadsheet.

    dave w

  3. #3
    Fuel Injected!
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    Good idea! I’ll try that out this week and post up my results.

  4. #4
    Fuel Injected!
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    OK, I rapped on it with a hammer and it looks like I got a little knock retard.

  5. #5
    Fuel Injected!
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    OK, I rapped on it with a hammer and it looks like I got a little knock retard. Not nearly as much as I would expect though.

  6. #6
    Fuel Injected!
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    There are at least 5 knock sensors for that computer. V-6, 305 manual trans, 305 auto trans, 350/454 manual trans and 350/454 auto trans. Being a different block completely you will have to see which one is more accurate in your block. Then there is also the knock sensor circuitry in your memcal
    Last edited by In-Tech; 1 Week Ago at 11:23 PM.
    -Carl

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