What Causes Engine Shaking and Loud Noise During Cold Start?
3 Answers
Cold start engine shaking and loud noise are caused by: 1. Excessive oil viscosity before reaching normal operating temperature; 2. Higher than normal RPM; 3. Mechanical components not yet at optimal temperature. The engine system consists of: 1. Valve train; 2. Crankshaft and connecting rod assembly; 3. Ignition system; 4. Cooling system; 5. Lubrication system; 6. Starting system; 7. Fuel supply system. Engine maintenance methods include: 1. Using qualified engine oil; 2. Using qualified coolant/antifreeze; 3. Regular radiator descaling; 4. Periodic engine carbon deposit cleaning; 5. Timely replacement of three automotive filters; 6. Maintaining appropriate RPM.
The engine shakes violently and is noisy during cold starts? I've encountered this issue several times myself. Right after starting, the RPM is unstable, the steering wheel vibrates, and it feels like the whole car is throwing a tantrum. The main problems lie in a few areas: when the temperature is low, the engine oil is too thick to flow properly, causing dry friction inside the engine, which leads to shaking; older cars are particularly prone to carbon buildup, which clogs the throttle body and fuel injectors, affecting air intake; if the spark plugs' ignition performance deteriorates, misfiring cylinders will definitely make the engine shake like it's dancing; also, worn-out engine mounts can't suppress the vibrations effectively. Once, after cleaning the throttle body and replacing the spark plugs, the car immediately became quiet, making my morning drives much more pleasant.
Last winter, my car sounded like a tractor during cold starts. After some research, I found the core issue was combustion problems. During cold starts, the coolant temperature sensor tricked the engine into injecting too much fuel, leading to incomplete combustion. One overlooked factor was the fuel pressure regulator—unstable pressure directly affects fuel injection volume. Additionally, if the exhaust manifold gasket leaks, the oxygen sensor data becomes inaccurate, worsening the shaking. The worst culprit was low-quality engine oil, which had terrible low-temperature fluidity, almost like syrup. I recommend trying a fuel system cleaner paired with high-fluidity engine oil—it’s low-cost and delivers quick results.
