How to Detect Engine Misfire in a Car?
1 Answers
When the car exhibits noticeable body vibration at idle, weak acceleration with body vibration at low RPM, reduced vibration at high RPM, or lower temperature on the spark plug insulator ceramic when touched by hand, it indicates engine misfire. The relevant details are as follows: 1. At idle, the body vibration is obvious. Observe the exhaust pipe outlet—the exhaust gas flow shows clear intermittency, accompanied by severe exhaust pipe shaking and distinct "popping" or thumping sounds. 2. At low RPM (around 2000), the body vibrates noticeably with weak acceleration, while the vibration diminishes at higher RPM. This phenomenon is often related to the ignition coil. Open the engine hood and observe the running engine: if it exhibits significant abnormal shaking (beyond normal operational vibration with large amplitude), you can begin checking for misfire. 3. After turning off the engine, touch the insulator ceramic of each spark plug by hand (cylinder 1 in a 4-cylinder engine is harder to reach). If a cylinder's temperature is lower, it indicates abnormal operation. You can also use a screwdriver to short-circuit the spark plug or disconnect the cylinder wire for a cut-off test. If the engine operation shows no significant change after disconnection, it confirms the cylinder is not working. A car missing one or two cylinders can still start.
