2. Make sure the air intake hoses are installed securely.
3. Warm up the engine.
4. Use a vacuum gauge to measure the vacuum in the intake manifold at idle speed (no load). If the measured value is not within the normal range, check the following:
- compression in the engine cylinders (see chapter "Mechanical part of the engine")
- check valve
- installation areas of each vacuum hose
- throttle body installation area
- fuel injector installation areas
- crankcase ventilation valve installation area
- intake manifold installation area
Note: Standard vacuum value: -60 kPa (-450 mm Hg).