Oscilloscope Measurement of Engine Dual Variable Valve Timing Waveforms

[Introduction]Variable valve timing VVT is a technology used in automotive piston engines. VVT technology can adjust the overlap time and timing of the engine’s intake and exhaust systems, reducing fuel consumption and improving efficiency.

Variable valve timing, VVT, is a technology used in automotive piston engines. VVT technology can adjust the overlap time and timing of the engine’s intake and exhaust systems, reducing fuel consumption and improving efficiency. The variable valve timing system is composed of a solenoid valve and a variable camshaft phase adjuster. By adjusting the cam phase of the engine, the intake air volume can be changed with the change of the engine speed, so as to achieve the best combustion efficiency and improve the fuel economy.

Let’s see how to connect the oscilloscope:

Connect a BNC-to-banana cable to each of the four channels of the oscilloscope, connect a needle to each of the red banana ends of the four BNC-to-banana cables, and connect an alligator clip to each of the black banana ends. The variable camshaft timing adjuster has two Circuit connections, one ignition positive and one ground negative. We insert the needle on the red banana head of channel one into the signal line of the variable camshaft timing adjuster on the intake camshaft actuator, and insert the needle on the red banana head of channel two into the adjustable camshaft actuator on the exhaust camshaft actuator. The signal wire of the variable camshaft timing adjuster, the alligator clip on the black wire banana head of the two channels is grounded.

If our oscilloscope has two channels, the connection is now complete. If it is four channels, we can also pierce the needles on the red banana heads of channel three and channel four into the variable camshaft timing on the intake camshaft actuator. The ground wire for the adjuster and the ground wire for the variable camshaft timing adjuster on the exhaust camshaft actuator.

Turn on the oscilloscope, adjust the attenuation ratio of the four channels of the oscilloscope to 1X, adjust the vertical scale of the channel to 5V/div, and set the time base to about 5ms. Turn on the low pass settings of channel 1 and channel 2 and adjust them to 30K. Adjust the trigger level of channel 1 to the channel waveform to stabilize the waveform.

The oscilloscope with built-in auto repair kit can select the variable valve timing in the actuator, select double, and click OK to complete the above settings with one key, which is more convenient and fast.

Generally speaking, we need to ensure that the engine can output the maximum torque. The traditional camshaft engine can achieve its best charging effect only within a specific speed range. As the speed increases, the charging efficiency will decrease, resulting in a decrease in engine torque. Extending the opening time of the intake valve is one of the solutions, but this will lead to an excessively large valve overlap angle during low-speed operation, serious exhaust gas backflow, and affect the engine torque output. In order to solve this problem, the camshaft timing adjustment system is technically adopted, which can adjust the timing of valve opening and closing, so as to improve the charging efficiency in a wider speed range, and at the same time improve the fuel economy of the engine.

The variable camshaft timing solenoid valve actuator is usually powered by the ignition positive wire and grounded by the ECM. Its signal is a pulse signal, and its duty cycle is determined by the manufacturer’s design, so compare the two actuators with each other. When the air ratio is used, the relevant technical information of the manufacturer should be consulted.