What causes intermittent idling shaking and gasping in a BMW 523?
3 Answers
Engine idling shaking and gasping may be caused by excessive carbon buildup in the intake tract or a cylinder misfire. Cylinder misfire occurs due to issues in the ignition system. In such cases, it is recommended to clean the carbon deposits in the intake tract and then inspect the ignition system. Here is additional information: 1. Ignition system issues: The ignition system of a car engine mainly consists of ignition coils and spark plugs. Spark plugs are wearable parts that require regular replacement. Over time, the electrode gap of spark plugs increases, and carbon deposits accumulate on the electrodes. If the electrode gap widens and carbon deposits form, the spark plug's ignition energy will decrease, affecting the engine's combustion. If the engine's internal combustion is affected, it can result in reduced power and shaking. 2. Excessive carbon buildup in the intake tract: If there is too much carbon buildup in the intake tract, it can affect the engine's air intake, thereby impacting combustion. Carbon buildup is normal in engines that run for long periods, so it is advisable to regularly clean the carbon deposits inside the engine. Carbon deposits can also cause engine knocking, which is an abnormal combustion phenomenon. If knocking occurs, it can affect the engine's power output and fuel efficiency. Severe knocking may even lead to connecting rod deformation or piston cracking.
The BMW 523 shakes and hesitates at idle, and I suspect there's an issue with the ignition system. Worn-out spark plugs or aging ignition coils can cause uneven engine firing, leading to severe shaking at idle. If the mass airflow sensor is dirty, the intake air volume fluctuates, resulting in incorrect air-fuel mixture ratios, causing jerky movements like hiccups. Excessive carbon buildup on the throttle body can also lead to unstable throttle opening, causing uneven air supply. A faulty oxygen sensor may mislead the engine control unit about the air-fuel ratio, making the hesitation more noticeable when stopping at traffic lights. I recommend checking these common issues first—inspect the spark plugs yourself for black deposits or use a diagnostic tool at a repair shop to read error codes. Ignoring this long-term will increase fuel consumption, accelerate engine wear, make driving uncomfortable, and may even lead to breakdowns, so don't delay. Regular maintenance, such as cleaning intake components and replacing spark plugs, can prevent many problems.
I've been driving this 523 for several years and have experienced idle shaking a few times. That gasping sound is particularly annoying. During one inspection, I found the spark plugs were completely worn out. After spending over 200 yuan to replace them, it ran smoothly again. It could also be the fuel system causing trouble—clogged fuel injectors leading to poor fuel supply or unstable fuel pump pressure, making the engine fluctuate like it's starving. If the engine mounts are worn out, vibrations transfer directly to the body, especially noticeable when the AC is on or when idling. Carbon buildup is another issue—frequent short trips in the city cause deposits in the throttle body and cylinders, leading to intermittent problems. I've tried using fuel additives and taking highway drives to clean out carbon deposits, which sometimes helps, but for severe symptoms, it's best to get a professional inspection at a proper shop. Remember, small issues left unattended can lead to costly major repairs—safety first.
