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th350 modulator tpi

Discussion in 'The Garage' started by PeteH, May 30, 2006.

  1. PeteH

    PeteH 1/2 ton status

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    so anybody run a th350 with tpi
    where do i hook up the vacuum line for the modulator?

    theres only 3 lines on the plenm for map, brakes, and fpr.. and i dont think your really supposed T into any of those. do i route the modulator vac line to the port underneath the tb? eeerg
     
  2. PeteH

    PeteH 1/2 ton status

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    c'mooonn :(
     
  3. 1979jimmy350

    1979jimmy350 1/2 ton status

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    you also have hookups on the throttle body its self. or you can put a T into one of the rear lines, if you are to worried about that then you can always drill into the manifold and tap the hole for another fitting
     
  4. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Yep, there are two vaccum ports on the throttle body. One underneith, and one on the side by the fresh air intake for the PVC system.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Where's the EGR takeoff? Isn't that one in back there near the MAP feed?
     
  6. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    EGR takeoff is up front from the nipple that comes out from underneith the throttle body. It also winds up feeding the AIR solenoids if installed. Not entirely sure what the big nipple on the pass side of the intake is used for though.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Is that a MAP/MAF difference? I've got a MAP plenum, I'm almost positive that the hard black plastic line that feeds the EGR solenoid comes right off the back near where the MAP sensor mounts.

    At some point over on thirdgen there was a post about the various ports at the throttle body, I just can't recall if any of them were "timed", like EVAP.

    The big nipple on the intake I believe is the EVAP hose connection.
     
  8. PeteH

    PeteH 1/2 ton status

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    ok i'll put it underneath the tb. by the way i dont have emissions stuff. thanks guys, you rock.
     
  9. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Sorry a bit late on this one..
    If i can remember, i believe i hooked up the power booster line for the brakes to the nipple on the drivers side middle of the plenum.. and the rear corner to the modulator.
    If not then i probably T'd into the rear corner nipple and ran one line to the power booster and the other to the modulator.
     
  10. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    My intake is hooked up as follows:

    Rear large nipple on the driver's side goes to the brake booster
    Smaller rear pass side nipple to the fuel regulator, larger pass side nipple to the MAP sensor, and both front nipples plugged off. I am not running EGR on my rig BTW :)
     
  11. PeteH

    PeteH 1/2 ton status

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    thats how i have it hooked up. but with the modulator line going to the one on the bottom of the tb. the other is capped. now if my truck would just start...
     
  12. PeteH

    PeteH 1/2 ton status

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    well my truck runs..and it sounds great...except one thing...the shifting. it doesnt. well just not out of first i guess. i'll check vac lines again for the modulator.. i may just take the line off the tb and just t into the brake booster like ryan said.
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Just make sure you've got vacuum all the time to the line. Vacuum gauge and run through the full motion of the throttle body and make sure its not on a ported point (I didn't think any were) or you can try to feel with your finger.

    My TH400 would shift without any vacuum input, but I've no clue about the TH350's. I'd think they would too? (but higher/harder)
     

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