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Home › Honda › 1978 › Accord Base, Automatic Trans › Repair and Diagnosis › Engine Performance › Engine Control Systems › Exhaust Emissions System - Throttle Control System › Trouble Shooting › Throttle Valve Closes In Less Than One Second › 1978-79 Models

1978-79 Models

  1. Disconnect vacuum hose from throttle control diaphragm. Connect vacuum gauge to hose. Vacuum should be at least 1.2 in. Hg at 4000 RPM.
  2. On all automatic transmission and Federal manual transmission equipped models, if there is vacuum, replace dashpot check valve and repeat THROTTLE OPENER SYSTEM test.
  3. On 1978 models and 1979 Civic high altitude and California manual transmission equipped models, if there is vacuum, by-pass throttle control valve and repeat THROTTLE OPENER SYSTEM test.
  4. If throttle return time is within specification, replace throttle control valve. If throttle return time is still less than one second, check for vacuum at dashpot.
  5. If vacuum is available, replace dashpot check valve. If no vacuum, check hoses for leaks. Remove throttle control by-pass and repeat THROTTLE OPENER SYSTEM test.
  6. On 1979 Accord and Prelude high altitude and Calif, manual transmission equipped models, if there is vacuum, replace control valve and repeat THROTTLE OPENER SYSTEM test.
  7. On all models, if no vacuum is available, check for vacuum at carburetor vacuum port. If vacuum is available at carburetor vacuum port, check hoses for leaks or blockage. Repeat THROTTLE OPENER SYSTEM test. If there is no vacuum at carburetor, clean port and repeat THROTTLE OPENER SYSTEM test.
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