EXAMPLE 1 : LEAK THROUGH EXHAUST VALVE OR INTAKE
MANIFOLD
The normal wave-form is shown in paler tone for comparison with the darker abnormal wave-form.
EXAMPLE 2.
INTAKE VALVE NOT CLOSING
If one of the intake valves is not closing completely, it means that the combustion chamber is
continuously connected with the intake system. During the combustion cycle, a high pressure wave
will 'blow back' to
the carburettor creating positive pressure in the intake manifold. The trough of the
vacuum wave-form (the low point of the displayed dynamic band of that cylinder), will move under the
Pa
line towards the
P+
side, reflecting this positive pressure.
EXAMPLE 2 : LEAKING INTAKE VALVE
The normal wave-form is shown in paler tone for comparison with the darker abnormal wave-form.
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