Variable Camshaft Timing (VCT)
| ITEM | DESCRIPTION |
|---|---|
| 1 | Inlet camshaft Variable Camshaft Timing (VCT) actuator |
| 2 | Exhaust camshaft Variable Camshaft Timing (VCT) actuator |
| 3 | Exhaust Variable Camshaft Timing (VCT) solenoid |
| 4 | Camshaft Position (CMP) sensors |
| 5 | Inlet Variable Camshaft Timing (VCT) solenoid |
The timing of the inlet and exhaust camshafts can be adjusted independently by an electro-hydraulic controlled Variable Camshaft Timing (VCT) system. The Powertrain Control Module (PCM) controls the system using information from the Camshaft Position (CMP) sensors and the Crankshaft Position (CKP) sensor.
The VCT system varies the timing of the intake and exhaust camshafts to deliver optimum engine power, efficiency and emissions. The timing of the intake camshafts has a range of 62 degrees of crankshaft angle. The timing of the exhaust camshafts has a range of 50 degrees of crankshaft angle.
In the base timing position:
- The intake camshafts are fully retarded.
- The exhaust camshafts are fully advanced.
| CAMSHAFT | VALVE OPENS | VALVE CLOSES |
|---|---|---|
| Intake | 33 degrees Before Top Dead Center (BTDC) to 29 degrees After Top Dead Center (ATDC) | 197 to 259 degrees ATDC |
| Exhaust | 236 to 186 degrees BTDC | 6 to 56 degrees ATDC |
The system consists of a VCT unit and a VCT solenoid for each camshaft. The PCM controls the system using Pulse Width Modulation (PWM) signals to the VCT solenoids.
The torsional energy generated by the valve springs and the inertia of the valve train components are used to operate the system.