What Causes the BMW 523 to Shake During Cold Starts?
2 Answers
Cold start shaking may be caused by carbon deposits, weak ignition, low cylinder pressure, or substandard fuel. Reasons for cold start shaking: It could be due to excessive carbon buildup in the throttle body, fuel injectors, or intake manifold; mechanical failures in components like ignition coils, spark plugs, or fuel injectors leading to cylinder misfires; or insufficient power caused by low fuel pressure or cylinder pressure. Solutions: Shaking during cold starts is usually temporary and will disappear once the engine oil reaches the appropriate operating temperature. If the shaking persists, it is necessary to inspect the engine's condition, including the throttle body and spark plugs.
I've encountered similar situations before. For cars like the BMW 523, cold start shaking usually has several common causes. The most common ones are aging spark plugs or ignition coil failure - when they can't ignite properly in low temperatures, the shaking becomes severe; carbon buildup in the throttle body affects the air-fuel mixture concentration, leading to unstable intake and consequently shaking; when engine oil has poor fluidity in cold conditions, insufficient oil supply from the oil pump also makes the engine tremble; insufficient fuel pump pressure or clogged fuel injectors can cause uneven fuel supply; and carbon deposits accumulating in the cylinders lead to incomplete combustion, exacerbating the shaking. For safety, I recommend first trying to replace the spark plugs and clean the throttle body. If it still shakes, then check if the ECU sensors are improperly calibrated - for example, a malfunctioning oxygen sensor could also cause problems. Don't neglect regular maintenance, especially using the right low-temperature engine oil can prevent this issue.
