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Throttle Position Sensor or Vac advance

Discussion in 'VB - VK Holden Commodore (1978 - 1985)' started by 1985VK, Jul 10, 2019.

  1. 1985VK

    1985VK Active Member

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    Just curious about the TPS Throttle Position Sensor/Switch on the carby of the VK. It has two wires to the microswitch. How does it work? How it does it tell where the throttle is at?
     
    Last edited: Jul 10, 2019
  2. 1985VK

    1985VK Active Member

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    I just found out how it works. It goes on a VK EST carby instead of a non EST carby. The mechanic swapped out the EST carb for a non EST carb and put the microswitch on it anyway. It does not work as it should and is only attached to the bracket by one bolt because the front of a VH carby is wider. The bracket doesn't fit properly ... and he didn't bother to tell anyone ...

    So there is no lever to act on the microswitch. When the plunger is pressed down there is no lever to do anything ... the microswitch just sits there ... this bloody carb has been like that for yonks ... it seems like an on or off kind of thing ... very basic ...

    So this EST engine has a non EST varajet on it ... no wonder it pings at operating temp under load ...
     
    Last edited: Jul 12, 2019 at 10:01 AM
  3. commy vk

    commy vk Active Member

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    Hi there VK I used to set this bloody thing up back in the day and it did work believe it or not
    Have since ditched the POS computer.
    Did your car only start pinging since carb change?
    What fuel are you using?
    Has the head had any work done like hardened seats etc?
    Have U still got the computer hooked up?
     
  4. 1985VK

    1985VK Active Member

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    Yes it has been pinging since the change. It is good when cold under load but when its warmed up it starts to ping. I don't know why they call it pinging, it sounds more like shaking a baby rattle to me. The head is factory standard. The computer is still hooked up.

    I was looking over the engine and noticed the microswitch on the carby looked a bit strange. It just had the 2 wires to it and the lever was missing that worked off the plunger. It has power to it but nothing can press against the switch. I presume it thinks it is always under load?
     
  5. commy vk

    commy vk Active Member

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    Okay the rattle that U can hear is the sound the valves are making when they are self destructing, sounds like a diesel so I wouldn't
    be driving it too much but it's up to you.
    Having the stock head still on is a recipe for disaster so the best thing that I can suggest is to go get a changeover head that has been recoed
    and the seats will be hardened so as to take the **** fuel that we are given now days.(god I miss Super grade)
    Other things like K line guides and stainless valves are all good as there are lots of things that can be done to them so speak to the reconditioner and see what he thinks.
    I ditched the EST crap and went with a VH distributor which has a Vac advance and she runs sweet,in fact I have never had her running so dam good.
    Have U still got the electric choke?
    Does she smoke on start up?
     
  6. 1985VK

    1985VK Active Member

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    Yep got the electric choke. No smoke on start up. The engine runs well otherwise, just rattles a bit here and there when it gets warm and under load at operating temperature. The rattle is faint but i can hear it. I thought it was because the timing is out. If i give it more juice the rattle goes away but i'm being heavy on fuel to get away from the rattling.

    It has a non EST carby on it anyway (with a vac port so no need to drill it out) and a TPS without the lever for it. If i changed over to a vac advance dissy would the rattling go away?
     
    Last edited: Jul 11, 2019
  7. commy vk

    commy vk Active Member

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    What RON fuel R U using?
    R U running it on a EST Dissy cause You can't adjust the timing to possibly eliminate the pings.
     
    Last edited: Jul 11, 2019
  8. 1985VK

    1985VK Active Member

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    95 but still pings on 98. It does not rattle when it is cold. Yep running it on an EST dissy. It seems it can't advance/retard enough as it should. Without the EGR and a non EST carby on it can't help either with no lever for the TPS.
     
    Last edited: Jul 12, 2019 at 9:41 AM
  9. 1985VK

    1985VK Active Member

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    Can anyone suggest a dissy to suit?
     
    Last edited: Jul 12, 2019 at 9:40 AM
  10. 1985VK

    1985VK Active Member

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    Does it rattle because the EST computer cannot adjust the timing fast enough? Is it a limitation of the computer or because we aren't on super petrol any more?
     
    Last edited: Jul 12, 2019 at 10:03 AM
  11. 1985VK

    1985VK Active Member

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    Thanks for this. RU saying an EST system cannot adjust the timing that much?
    Is the timing very limited compared to a vac dissy?
     
  12. commy vk

    commy vk Active Member

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    EST is non adjustable you can turn the dissy till the cows come home
    I can run my VK on 91 no dramas
    Have U still got all the anti pollution garbage hooked up?
    THe old super grade petrol contained lead and that's what cushioned the valves
    so as soon as the changeover to unleaded happened a lot of these classic old work horses
    were either scrapped or just left to rot,which is a shame.
    I wonder if the old ex GMH engineers see a VK still being driven around go "WOW".
     
  13. 1985VK

    1985VK Active Member

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    Wow you can run it on 91! The VK is a head turner. Every now and again someone looking on in astonishment and it gets smiles.
    If the EST cant cope, the best thing to do is change out the dissy

    I just need to work out which one to get. When the new dissy goes in will all i have to do is disconnect the EST in the kick panel?

    Did you get a new coil when you changed out your dissy?
     
    Last edited: Jul 12, 2019 at 11:14 AM
  14. the_boozer

    the_boozer no more VK

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    just pull the est fuse. Est uses the same coil as hei.
     
  15. commy vk

    commy vk Active Member

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    Nah I kept the old one which works fine
    Have U got a timing light (old school must have)
     
  16. 1985VK

    1985VK Active Member

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    Yeah got a timing light.

    There seem to be 2 types of coils around. The original oil filled GTR type and the later plastic encased (Bosch HEC 716)

    Decisions decisions ...
     
    Last edited: Jul 12, 2019 at 12:42 PM
  17. 1985VK

    1985VK Active Member

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    Do you mean a HEI can use the same standard coil? I presume its easy to swap out the EST dissy?
     
  18. the_boozer

    the_boozer no more VK

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    yes the same part for both systems . Id be suss the cheapy you linked to is MEC as it has a coil supplied with it. Meaning the module will burn out if you use the HEI coil with it but Im only guessing it is.
     
  19. commy vk

    commy vk Active Member

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    Coil I'm using is a RG 1503 came with the car (stockie)
     
  20. 1985VK

    1985VK Active Member

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    You mean this one? https://www.ebay.com.au/itm/202054103713

    What is MEC?
     

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