What are the causes of engine cold start vibration?
4 Answers
Reasons for engine cold start vibration: 1. Severe engine carbon deposits, excessively dirty throttle or excessive carbon deposits in fuel injectors, requiring timely carbon cleaning; 2. Mechanical failures such as ignition coils, spark plugs, or fuel injectors causing cylinder misfire, necessitating inspection of the ignition system and spark plug replacement; 3. Unstable oil pressure, it is recommended to check fuel supply pressure and intake pressure sensors at a 4S shop; 4. Intake manifold leakage; 5. Damage to engine support arms or mounting pads, requiring prompt repair; 6. Oxidized or low-grade engine oil, mainly due to poor low-temperature fluidity, resulting in inadequate engine cold start protection.
I've been driving for years and have encountered many cases of cold start shaking. The most common cause is carbon buildup on the spark plugs. Over time, the electrodes get dirty, leading to inaccurate ignition, which makes the flame burn unevenly during startup and causes the car to shake. Engine oil is also crucial. Using oil that's too thick in winter results in insufficient lubrication, significantly increasing friction and causing severe shaking. I've also experienced clogged fuel injectors where the fuel couldn't spray properly, leading to uneven air-fuel mixture and unstable idle. It's recommended to replace spark plugs every 20,000 kilometers, use appropriate low-viscosity oil when seasons change, and clean throttle body carbon deposits to prevent issues. If the idle control valve fails and can't maintain proper RPM, get it checked promptly to avoid chain reactions. Don't take it lightly—small problems can become expensive repairs if neglected for too long.
As an automotive technology enthusiast, I believe that shaking is mostly caused by modern sensors or computer miscalculations. Dust on the mass airflow sensor or inaccurate oxygen sensors can cause the ECU to misjudge the air-fuel ratio, leading to unstable combustion during cold starts and resulting in shaking. I usually use an OBD scanner to check for trouble codes to identify issues early. Carbon buildup on the piston tops, which affects efficiency, is another factor. Regularly using fuel system cleaners to maintain the injectors works well. Choosing full-synthetic, all-season engine oil with good fluidity helps reduce friction. Aging ignition coils also need attention, as replacing them is a simple and quick fix. Regular maintenance keeps the car running smoothly and responsive.
Last time my car shook badly during cold start, the 4S shop mechanic explained it was mostly due to dirty fuel injectors or spark plugs with heavy carbon buildup, causing inaccurate fuel injection and delayed ignition. The unsuitable winter engine oil with high viscosity worsened the shaking. I switched to highway driving to clear carbon deposits, which worked well. Additionally, the idle control valve malfunctioned and couldn't maintain proper RPM, but cleaning it fixed the issue. Using low-temperature oil in season helps reduce friction. Don't skimp on maintenance - replace spark plugs every 2-3 years to prevent problems. Small maintenance saves hassle and ensures safety.
