Checking the Induction System
Checking the Induction SystemTools:
- Pressure testing equipment No.83 93 514
- Start gas
1 Where appropriate, check the following for leakage
- auxiliary air valve/idle air control valve
- brake servo
- bleed valve
- vacuum tank
- pressure switch
- EGR thermostatic valve
- EGR valve
- fuel pressure regulator
Also check that:
- the throttle closes
- the three throttle body retaining bolts are tightened.
2 Check that the injectors are correctly fitted in the intake manifold and that the 0-rings are undamaged.
If air leakage is still suspected after carrying out these checks, continue checking as follows:
3 Connect pressure testing equipment 83 93 514 to the intake manifold after the throttle and suspend the pressure. gauge vertically.
4 Start the engine. Run it at idling speed, 875 ± 50 rpm.
Check the vacuum, which if everything is in proper working order should be 0.4 - 0.8 bar (5.8 - 11.5 psi)
If the vacuum is less than 0.4 bar (5.8 psi), there is air leakage in the induction system. In such case, check again as described above.
5 Also check the induction system for air leakage, before the throttle and up to the air cleaner. For turbo engines, see "Pressure-testing the turbo system".
Useful tip
Suspected leakage may also be discovered by spraying start gas on suspected areas when the engine is running at idling speed. If leakage exists, engine speed will tend to increase.