What is the working principle of VVT valve? Is there a fault code when it is generally broken?

The working principle of VVT valve is that piston engines usually intake and exhaust air through the lift throttle, and the lift valve is directly or indirectly driven by the cam on the camshaft. If it is broken, there will be a fault code.

The variable valve timing system of OCV VCT Company consists of solenoid valve (OCV) and variable camshaft phase adjuster (VCT). By adjusting the engine cam phase, the intake air can be changed with the engine speed, so as to achieve the best combustion efficiency and improve fuel economy.

VVT crankshaft drives camshaft through timing belt, gear or chain. The profile and position of the cam on the camshaft are usually optimized for a specific engine speed, which usually reduces the torque at low speed and the power at high speed.

Simply put, the VVT system is to adjust the angle of the camshaft within a certain range by installing a hydraulic mechanism at the transmission end of the camshaft, which is equivalent to adjusting the opening and closing time of the valve.

Extended data

Fault range of VVT valve difficult to start (normal engine rotation):

① Circuit failure

Spark plug and ignition coil failure; The high-voltage line leaks electricity, and the wire connection is loose or disconnected.

② Oil circuit fault

The fuel pipe (including hose) is dirty or blocked, and the fuel pump is faulty (check the fuel pressure).

③ Electronic control part

Electronic throttle body assembly failure or APP sensor failure, ECT sensor failure or MAF sensor failure, ECM failure, camshaft position control system failure.

④ Mechanical part

Low cylinder pressure (poor spark plug fastening or gasket failure); Valve seat pressure leaks, valve stem sticks, valve spring force is insufficient or damaged; The cylinder gasket leaks, the piston ring is stuck or damaged, and the piston, piston ring or cylinder is worn; PCV valve failure, intake manifold pad or throttle body pad intake.