What causes the chugging sound when starting the car in the morning?
2 Answers
The reasons for the chugging sound when starting the car in the morning are: 1. Engine idle vibration, producing a "chugging" sound that disappears when the speed increases, and the operation becomes smooth; 2. The engine produces a rhythmic chugging sound at various speeds, accompanied by severe engine vibration and difficulty in acceleration; 3. The engine runs well at low speeds but produces irregular chugging sounds at medium speeds, and the car lacks power. If the engine produces unrhythmic chugging sounds at low, medium, and high speeds and emits black smoke, improving during rapid acceleration indicates a too-rich mixture. If there is no improvement and the chugging sound worsens, diagnose it as weak high-voltage spark. If rhythmic chugging sounds occur at low and medium speeds, troubleshoot it as a few cylinders not working. If the engine runs well at low and medium speeds but produces unrhythmic chugging sounds at high speeds, troubleshoot it as poor ignition system performance at high speeds.
If the car makes a sputtering sound when starting in the morning, it usually indicates low engine speed or weak starting power, possibly due to insufficient battery charge, especially in cold temperatures. I've encountered this issue often with older cars in winter. The simplest way to check the battery status is to measure the voltage with a multimeter; if it's below 12.4 volts, the battery needs charging or replacement. Another common cause is spark plug issues, where moisture or aging can lead to ignition failure; it's recommended to inspect and replace them every two years. There could also be fuel system problems, such as clogged injectors or insufficient fuel supply from the fuel pump, particularly making the engine hard to start after cold nights. Don't overlook the viscosity of the engine oil; using winter-grade oil with the appropriate viscosity can improve the situation. Ignoring the sputtering sound may damage the starter or lead to more significant problems, so it's essential to visit a repair shop promptly to diagnose key components when the issue is first noticed.
