What Causes Constant Engine Shaking?
2 Answers
Constant engine shaking can be caused by a dirty air filter, broken high-voltage wires, worn spark plugs, low idle speed, or clogged fuel injectors. The details are as follows: Dirty Air Filter: The air filter is designed to protect the engine and reduce wear. It should generally be replaced every 10,000 kilometers. If not replaced in time, insufficient air intake can lead to low idle speed, causing the engine to shake. Simply replacing the filter can resolve this issue. Broken High-Voltage Wires: Broken high-voltage wires refer to the interruption of the wire core, which can affect ignition and cause engine shaking. Use a multimeter to measure the resistance and replace the wire with significantly higher resistance. Spark Plug Lifespan: Spark plugs have a limited lifespan. After 30,000-40,000 kilometers, their ignition efficiency noticeably decreases, which can affect ignition. This is a common issue, and replacing all spark plugs can solve the problem. Low Idle Speed: The engine idle speed is preset in the car's computer. If the RPM drops below a certain range, the car's computer will automatically adjust it. If the idle speed is too low and causes shaking, it means it has exceeded the computer's control range. Some cars have an adjustment screw on the throttle body to regulate idle speed, while others do not. For such cars, check the idle control valve, throttle body, air flow meter, vacuum sensor, or adjust the ignition timing (for cars with distributors) to increase idle speed. Low coolant temperature can also cause low idle speed, so check and replace the thermostat if necessary. Clogged Fuel Injectors: The fuel injector in an EFI car is a critical component for fuel injection and has a long lifespan, often reaching hundreds of thousands of kilometers. However, deposits in gasoline can clog the injector nozzles, causing uneven fuel injection among the injectors. This leads to inconsistent cylinder operation and engine shaking. The solution is to remove and clean the injectors.
I've always loved studying cars. When the engine keeps shaking, it's mostly an issue with the ignition system, such as aging spark plugs or burnt-out ignition coils. I've seen many cases where the spark plugs' lifespan ends with broken filaments, or carbon buildup causes poor ignition, leading to severe shaking. The fuel system is another common trouble source—clogged fuel injectors disrupting fuel delivery or unstable fuel pump pressure can make the engine perform inconsistently. Excessive carbon buildup in the throttle body blocking air intake or a dirty air filter affecting the air-fuel mixture ratio can also be culprits. Additionally, worn engine mounts transmit more vibrations, making the ride especially bumpy. Over time, this can damage the engine, wasting fuel and accelerating wear. I recommend getting it checked at a professional shop early, starting with testing the spark plugs and fuel system to avoid major problems.
