VVT solenoid engine operation-7

Variable valve timing (VVT) solenoid

One {Acronym.VVT} solenoid is installed for the intake camshaft and one for the exhaust camshaft.
The {Acronym.VVT} solenoids are used to regulate the camshaft adjustment units, which in turn adjust the valve timings in the early or late directions. In this way the engine performance is increased and internal exhaust gas recirculation is realized. The {Acronym.VVT} solenoids for the intake and exhaust camshafts differ only in terms of the position of the fastening point by which they are fixed to the camshaft adjustment bridge.
Via the {Acronym.VVT} solenoid, under the prevailing EOP, a defined quantity of engine oil is allowed into and out of the camshaft adjustment units. In this way the valve timings are adjusted according to the operating condition of the engine.
The {Acronym.VVT} solenoids are actuated via a PWM signal by the PCM.

A----Bore hole for connection to chamber A

B----Bore hole for connection to chamber B

1----Solenoid coil

2----Valve stem

3----Engine oil pressure supply bore and ring groove for camshaft adjustment unit chamber B

4----Oil return ring groove

5----Engine oil pressure supply bore and ring groove for camshaft adjustment unit chamber A

6----Engine oil pressure supply bore for {Acronym.VVT} solenoid

7----Spring

8----Engine oil return bore

When idling and during deceleration, the {Acronym.VVT} solenoids are activated repeatedly by the PCM in order to remove any dirt which may be on the bore holes and ring grooves.
If a fault is detected on the {Acronym.VVT} solenoids, they are no longer actuated.
To avoid a malfunction of the {Acronym.VVT} units at excessively low ambient or engine-oil temperatures, they are activated by the PCM with a time delay via the {Acronym.VVT} solenoids. The PCM obtains the information needed for this purpose from the ECT sensor and the IAT sensor.