Any time you’re dealing with a combustion engine, there’s a chance it will develop a misfire. A better understanding of how computer systems analyze a misfire can make your job that much easier as the service tech.
The CMP actuator system controls the amount of intake and exhaust valve overlap. The engine control module (ECM) can only command the CMP actuator to advance the valve timing from the park position or retard the valve timing back to the park position.
One of the ways automakers squeeze more horsepower and torque from an engine is by adding variable valve timing (VVT) to the valvetrain. A conventional camshaft has fixed valve lift, duration and timing; so, the grind is always a compromise between fuel economy, performance and emissions. But with VVT, duration, valve overlap and timing can be changed on the go to optimize engine performance at different RPM, loads and operating conditions.
The variable “valve” timing that most of us see in our shops is actually variable “camshaft” timing that improves low- and high-speed torque by advancing or retarding the camshaft timing on single overhead camshaft (SOHC) engine applications.
Variable valve timing is becoming a standard system on most late-model engines because it offers higher performance from a smaller displacement engine at higher rpms. Oil plays a larger role in VVT systems. They need engine oil not only for lubrication, but also to actuate the camshafts to change the profile of the lobes. Oil