The drawback of using a cylinder pressure gauge to measure cylinder pressure is that it requires removing all spark plugs or injectors and checking each cylinder individually, which is time-consuming and laborious. Therefore, another method for measuring cylinder pressure was invented – the cylinder pressure tester. Cylinder pressure testers mainly include pressure sensor type cylinder pressure testers, starting current type cylinder pressure testers, and induction discharge type cylinder pressure testers, used to evaluate the balance of cylinder pressure in each cylinder.
1) Pressure sensor type cylinder pressure testers pick up the pressure signal inside the cylinder through a pressure sensor, convert it from analog to digital using an A/D converter, and then send it to a display device to measure cylinder pressure. When testing cylinder pressure using this method, remove the spark plug or injector of the cylinder being tested, rotate the pressure sensor mounted on the machine, and use a starter to rotate the crankshaft for 3-5 seconds.
2) Starting current type cylinder pressure testers: The resistance torque during engine starting mainly consists of two parts: the friction torque generated by the crankshaft and connecting rod mechanism and the counter-torque of the compressed gas during the compression stroke of each cylinder. Frictional torque is considered a stable constant, while the reaction torque of the compressed gas during the compression stroke of each cylinder varies depending on the pressure in each cylinder. The torque required by the starter to rotate the engine crankshaft is a function of the starting current; there is a corresponding relationship between changes in the starting current and changes in cylinder pressure, and the starting torque is directly proportional to the cylinder pressure. Therefore, if the goal is not to obtain specific values for the cylinder pressures of each cylinder, but rather to compare whether the cylinder pressures are balanced, the pressure of each cylinder can be evaluated by measuring the changes in the starting current during startup.
