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Buick V6 Throttle adjustments

Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by MathiaS, Jan 26, 2012.

  1. MathiaS

    MathiaS New Member

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    Hi Guys,
    I have a 93 VR which i just put a 70mm Throttle body on and need some advice on possible adjustments

    Just a bit of backstory, when i first put the new TB on, the engine idled at over 1500 RPM (with the old TB it sat at around 1000) so i had to adjust the close stopper so the butterfly could close up almost completely, Its now sitting at 1200 RPM and I'm Very happy with Performance and how smooth the engine is.
    The problem lies in that i had to adjust the throttle cable so it didn't sit open because of that and now the new TB will not open completely.
    So my real question is, is there any way to gear this cable so that when i push my accelerator 1 CM the throttle body will move 1.2 CM (this would probably be far far too much but just for arguments sake) or is there any built in way to adjust this without affecting the idle speed.

    Cheers in advance
     
  2. Jonah 101

    Jonah 101 Undefined

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    Does the 70mm throttle body not have a IAC valve?
     
  3. Jxfwsf

    Jxfwsf Well-Known Member

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    no gears it's basic use of levers, you'd want to move the cable attach point closer to the center *edited was thinking of it backwards*
    now adjusting the screw to change your idle will mess the ecu up as it'll be trying to close the iac to slow it down to it's predetermined rpm and will most likely throw it into lhm possibly iac, tps or vac leak error, close it to far and it will top the iac out and won't be able to raise the rpm, the plastic cap on them is to stop ppl changing it, cause to do it properly you'd want a tech2 or laptop hooked up so you can set it correctly.
     
    Last edited: Jan 26, 2012
  4. Jonah 101

    Jonah 101 Undefined

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    Sorry I see what he is on about now lol

    I think closer to the center is what you want.
     
  5. St3alth187

    St3alth187 More time than money

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    I was aware that a tune was required after a TB upgrade.
    PM The1 or Delcowizard
    I dont know the specifics of it, but these guys sure do.
    Cheers,
    Jake.
     
  6. Brett_jjj

    Brett_jjj Well-Known Member

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    Do the people who sell these larger throttle bodies, mention that you will also need to buy a tune to suit?
     
  7. Ghost

    Ghost Donating Member

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    No they dont
     
  8. Jonah 101

    Jonah 101 Undefined

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    Would you need a tune on an ecotec? Im asking because it has a MAF sensor.
     
  9. MathiaS

    MathiaS New Member

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    Cheers for all the responses, i am planning on getting it tuned but am waiting on my new injectors and fuel pump before i do it
    It does have the IAC Valve the only reason that i dropped the rpm with the Screw is that it was physically open too far and the IAC Valve couldnt do its job - the car is running fine at the moment no engine light no LHM and the acceleration is much smoother - better idle - everything is great with it on, just looking to get the power out of it at the moment.
    Really liking the idea of moving the joining point on the TB itself, Great idea gunna give it a shot
    Cheers to everyone for the help
     
  10. Jonah 101

    Jonah 101 Undefined

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    Have you removed the bell mouth? I'v heard mixed reviews about it but with 70mm TB It might pay too.
     
  11. MathiaS

    MathiaS New Member

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    i did the bellmouth the day i got the car
    i got a K 'n N panel Filter, extractors, High Flow Cat, 2.5" exhaust and the difference between the stock and 70mm TB was ridiculous noticed it instantly and when i boot it it goes harder than the stock TB which opened fully where the 70mm only opens about 60% plus down low the idle and coast is WAY smoother only bad part is the gear shift, since its an Auto
     
  12. Jonah 101

    Jonah 101 Undefined

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    Holding the gears too long?
     
  13. MathiaS

    MathiaS New Member

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    yeah Gears up about 1k too late if your giving it any go but then again its a 19yr old Box lol found if i throttle back its all good with the changes so gunna go easy till i get the Dyno Tune
     
  14. MathiaS

    MathiaS New Member

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    BTW Jonah u can get the Twin TB's for the Ecotec u need the manifold to suit
     
  15. Jonah 101

    Jonah 101 Undefined

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    Yeh thanks, but thats too much flow for what I have planned lol

    My ecotec is the same changing gears, memcal made this better. im unsure if the VRs trans is controlled by the ECU though..
     
  16. Andrew426

    Andrew426 Active Member

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    The VRs trans has electronic kickdown, controlled by the ECU based on the signal from your throttle position sensor, which is all on the piss now. You need a retune.
     
  17. The1

    The1 A Memcal a Day Keeps..

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    the adjustment for a Larger TB in the tune is for the TPS Gain, a larger TB will flow more at lower TPS than the smaller TB. You can get away without it on manuals but still best to get it adjusted, with auto's it's more of an issue as the Line Pressure Tables are controlled on one axis via TPS. Also depending where you buy the TB the stop screw may not be adjusted properly, you should sit at 0% TPS 500mv and 30steps IAC as a guide at IDLE.
     
  18. MathiaS

    MathiaS New Member

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    Thanks The1 and Andrew426 i noticed the stop screw was out straight away (idling at 1500RPM) dropped that back to where my old one sat RPM wise And learned all about the TPS Coasting along at 60 the Tacho would fluctuate around the 13 to 14 hundred RPM range erratically and i felt engine braking but this cleared up when i reset the IAC (with the 3k RPM on startup) and let out the stop screw Just right this seems to be perfect now i have also been playing with the settings and think i found a nice middle ground i have finally got it Right open (Swapped the cable Plate from my stock TB) and now when i put it down it gears down twice (tested this at 60KPH all times) whereas before only shifted once i have got it gearing up around the same place as it did on the old TB (around 300RPM above) now i'm still planning on getting this tuned in probably a month once i get my fuel gear just wondering if there are any other adjustments i should make or if this is going to hurt anything.
    Thanks again for the help guys your all legends.

    On a side note, anyone know if MRHDT in Dubbo is good??
     
  19. St3alth187

    St3alth187 More time than money

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    Your in Dubbo mate? Nice..
    Im in Nyngan lol :)
     
  20. LS1 James

    LS1 James Donates His Member

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    I wouldnt be doing any WOT runs until you sort it out. The fact that you're adjusting the throttle stop screw and are actually noticing a difference in RPM is proof enough.
    The IAC steps on a standard TB need to be @ 30 and adjusting the screw should have no effect on idle unless it is physically open so far that your TPS voltages are too high (which is most likely the case here) You also would have had a code thrown for sure but you wouldnt have seen it whilst adjusting the screw under the dash. It would be a TPS reference Error code.
    The CEL doesnt stay on all the time for it.
     

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