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Throttle Body

CAUTION: Do not adjust the throttle stop screw. It is preset at the factory.
  1. Start the engine and allow it to warm up until the cooling fan comes on.
  2. Disconnect the EVAP canister vacuum hose from the top of the throttle body and connect a vacuum gauge to the throttle body. See Fig 1 .
    Fig 1: Testing Throttle Body Vacuum
    G00125716Courtesy of AMERICAN HONDA MOTOR CO., INC.
  3. Allow the engine to idle and check that the gauge indicates no vacuum. If there is vacuum, check the throttle cable. See 1991-01 ON-VEHICLE ADJUSTMENTS - NSX & NSX-T article.
  4. Check that vacuum is indicated on the gauge when the throttle is opened slightly from idle. If the gauge indicates no vacuum, check the throttle body port. If the throttle body port is clogged, clean it with carburetor cleaner.
  5. Stop the engine and check that the throttle cable operates smoothly without binding or sticking. If there are any abnormalities in the above steps, check for:
    • Excessive wear or play in the throttle valve shaft.
    • Sticky or binding throttle lever at full close position.
    • Clearance between throttle stop screw and throttle lever at full close position.
    Replace the throttle body if there is excessive play in the throttle valve shaft or if the shaft is binding or sticking. See Fig 2 .
Fig 2: Inspecting Throttle Body Operation
G00125717Courtesy of AMERICAN HONDA MOTOR CO., INC.
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