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More Stupid questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by tRustyK5, Sep 5, 2000.

  1. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    What is the sensor on the block just above and ahead of the starter? Whatever it is, on mine it has power going to it. My truck has just started missing under load and occasionally cutting out on me. Oddly enough this happens just after a right turn 90% of the time. The reason I know that my sensor has power to it is that I heard it shorting a bit when I went to check my plugs. Somehow this must be interfering with my ignition. I will replace the bad wire but I still don't know what kind of sensor this is or why its affecting my ignition.
    Any ideas?

    [​IMG]
     
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Does an 81 have a knock sensor? Why does it have power, even with the key off? How does this afect my ignition? Sorry for all the questions but I've never had to deal with or replace any of these things before.

    [​IMG]
     
  4. Emmettology 101

    Emmettology 101 3/4 ton status

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    I forgot you had an older model. I doubt its a knock senesor then, sorry, I am at work and when I get too many things going I loose track! LOL

    Have you pulled it out? Maybe it is a temp sensor of some sorts..... Or a block heater?

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The 350 thats in there is not the stock engine (I know this does'nt help) And it used to have the HEI with something like 5 wires plugging in to the control module. I chucked that distributor and put the older style in. The older style has like 2 or 3 wires going into the control module. I did this about 1 1/2 years ago and have'nt had any problems until now.

    I seem to remember the early 80's trucks had "ESC" Electronic spark control. Maybe this is what the extra wires to the control module were for? Maybe this sensor used to be tied in to all this?

    Any other ideas?

    Rene

    [​IMG]
     
  6. riz

    riz 3/4 ton status

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    Remember, the only stupid question is the one not asked. If you don't ask, it can't be answered.

    <font color=purple>L8r,

    .Riz.<font color=purple>
     
  7. JimmyDie6.2

    JimmyDie6.2 1/2 ton status

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    I'm trying to understand what sensor you mean. I had an 81 SUB 350......could it be the cooling sensor....that would be in the head though I guess....mine was. some help I am.........when you find out please post it...I'm very curious now..........hmmmmmmmmmmmmm
     
  8. Emmettology 101

    Emmettology 101 3/4 ton status

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    Oh, you got me, I have never worked on anything with that ESC.... I have had 4 engine with HEI and now I have a full MSD set up.

    I would bet it is a coolant sensor.. I know there is plugs on the sides to drain coolant..... Have you followed the wires?

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Its down low on the block just behind the exhaust. It seems too low for a coolant passage. As far as I know the oil pressure is behind the distributor, temp is on the drivers side, but the mystery one has me stumped.

    Oh by the way the wire going to it is at least 12 guage, if that helps anyone.

    [​IMG]
     
  10. White Knight

    White Knight 1/2 ton status

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    I believe it is a Knock sensor by its locale...WK
     
  11. LAZYMON

    LAZYMON 1/2 ton status Premium Member

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    Two things it could be. A knock sensor or a sensor that would regulate an electric fan setup. Turns the fan on when it gets to a certain temp. My 84 TransAm with a 350 has both. The knock sensor sits farther forward.

    73 Topless Blazer
     
  12. DMK

    DMK 1/2 ton status

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    If it's a newer motor than it's an knock sensor. Since you don't have an computer just disconnect it. Are you sure it is hot all the time?
     
  13. archer

    archer 1/2 ton status

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    With that gauge of wire my vote is for the engine block heater.

    "who dares wins"
     
  14. archer

    archer 1/2 ton status

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    I found it in my shop manual, It's an esc sensor (electronic spark control) it's really a knock sensor, if you have a computer, a bad one will give you a code 43. if you don't you'll experience pronounced knock under load or higher rpm's. and retarded timing.

    "who dares wins"
     
  15. lowlevell

    lowlevell 1/2 ton status

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    If it is right in front of the starter it is definitly the knock senser.The knock sensor sends info to the ESC to retard the timing.Mine was bad in my 89 and it screwed my timing up.My knock sensor had a "mushroom" type of elec. connecter on it,not sure what they looked like in 81 though..Heck i didnt know they used them in 81..later
     
  16. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    If it is a ESC (knock) sensor, do I still need it with the old style HEI. The truck has no computer. I'm going to try and trace the wire today (if I can tear myself away this site) [​IMG]

    Thanks for all the input.

    Rene

    [​IMG]
     
  17. archer

    archer 1/2 ton status

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    It would appear that if you bypass the knock sensor with HEI you will adversely effect your timing. These manuals don't elaborate on the "what Ifs", I guess it's sort of like asking if you can run it without an AIR pump or catalytic convertor, we all know you can but it's taboo. In this case I'd err on the side of caution and keep it. If you do remove it, keep your ears open for knock, and check the timing for a while. Who knows, may give you 100 more HP.

    "who dares wins"
     
  18. sosamantx

    sosamantx 1/2 ton status

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    If you have no computer, and the older HEI (I am assuming the HEI only has 2-3 wires, hot, ground, and tach wire), then you shouldn't need it. I would just disconnect it (maybe tape it up) and see how it runs. - Steve

    <font color=blue>Steve Sosa a.k.a. "sosaman"</font color=blue>
    http://sosaman.home.texas.net/carpics.html
     
  19. Emmettology 101

    Emmettology 101 3/4 ton status

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    Yes, if you dont have a comp then disconnect and see what happens, I have ran three engine with HEI's and no knock senosrs of rcomps and they ran fine, I dont think there is anyuse for t since it would feed info to a computer.

    With that smoke stck coming out of the roof of you Igloo how do you keep the igloo from melting? [​IMG]

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     
  20. Emmettology 101

    Emmettology 101 3/4 ton status

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    Yes, if you dont have a comp then disconnect and see what happens, I have ran three engine with HEI's and no knock senosrs of rcomps and they ran fine, I dont think there is any use for t since it would feed info to a computer.

    With that smoke stack coming out of the roof of you Igloo how do you keep the igloo from melting? [​IMG]

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     

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