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chevy throttle body idle 5.7 set??

Discussion in 'Chevy Trucks' started by mushplows87, Dec 14, 2008.

  1. mushplows87

    mushplows87 Junior Member
    Messages: 11

    hello i have an 87 silverado that im getting ready to plow with.. the idle screw on the throttle body was messed with...after an extensive tune up and new ecm...its all thats left to set to factory specs...every bood and web site i find only says " no adjustment is needed) and i know thats true... but this one was turned way down ......how do i re-set it to factory spec??? thanks for any leads
  2. redhenny16

    redhenny16 Senior Member
    Messages: 134

    You will have to run the IAC all the way in and then unplug it. This requires an IAC driver tool, so you might just as well remove your IAC motor and tape the opening shut with several layers of duck tape. Make sure you unplug the IAC while it's out or it could over extend. You are doing this so that you can set base idle. Now you can start your truck and useing a timing light that has a tach or a scan tool set your base idle to 450-550 rpm. Whatever speed your truck will idle at, but if you go over 550 rpm it may raise your TPS reading which will then have to be reset. After your base idle is set bring your IAC back to normal, clear codes and retest. Good luck
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    You can also electronically retract the IAC pintle by jumping terminals "A" and "B" in the OBD1 connector plug under the dash together with a jumper wire, turning the key to the run position, and waiting about 30 seconds to allow time for the ECM to retract the pintle.

    Once you allow the time for the pintle retraction, disconnect the IAC connector plug (in order to adjust the idle speed without the IAC taking over). Be sure to remove the jumper AFTER you disconnect the IAC plug but BEFORE starting the engine to set the idle speed..

    After you set the idle speed and your finished you may have an unstable idle until the ECM relearns the idle...thats normal and will correct itself after a short drive time.
  4. mushplows87

    mushplows87 Junior Member
    Messages: 11

    thanks so much....it did the trick...thanks again Joe