Section 03-12: Air Intake System
1993 Mustang Workshop Manual
TESTING

Vacuum-Operated Systems Check

 

2.3L MFI Engine

 CAUTION: This check must be performed in ambient temperatures of not less than 16°C (60°F). Do not immerse any part of the vacuum-operated duct and valve assembly in water.

  1. Apply parking brake and block wheels.
  1. Remove air cleaner cover and element. Inspect heat riser tube and zip tubes for proper installation and/or damage. Service or replace as required.
  1. Ensure that valve door is in open (heat off, no vacuum) position when engine is not running. If door is closed, check for binding and sticking. Service or replace as required.

     CAUTION: Carefully position temperature indicator tool to prevent ingestion into the throttle body.

  1. Place temperature indicator as near as possible to temperature sensor in air cleaner cover.

     WARNING: DO NOT COOL TEMPERATURE SENSOR WHILE ENGINE IS RUNNING. IF R-12 REFRIGERANT IS DRAWN INTO THE THROTTLE BODY WHILE ENGINE IS RUNNING, POISONOUS PHOSGENE GAS WILL BE EXHAUSTED INTO TEST AREA. CONDUCT THIS PROCEDURE ONLY IN A WELL VENTILATED AREA.

  1. Start engine. If valve door has closed, proceed to Step 7. If valve door has not closed, turn off engine. Cool temperature sensor by spraying with liquid Refrigerant R-12 for 30 seconds after liquid contacts the air cleaner cover.

    Start engine. If valve door has closed, proceed to Step 7. If valve door is open during idle, perform Vacuum Motor and Valve Function Check.

  1. Install air cleaner cover and tighten screws.
  1. Run engine five minutes. Remove cover and observe door. If door does not start to open within a 5 minute period, note temperature.
    1. If temperature is greater than 24°C (75° F), replace sensor.
    1. If temperature is less than 24°C (75°F), temperature is insufficient to operate valve door. Install air cleaner cover, tighten screws and run engine for an additional 5 minutes. If valve door has not started to open, replace sensor.
  1. Turn off engine. Remove all test instruments and install all system components. Start engine and check for vacuum leaks. Service as required.