What Causes Intermittent Idle Shaking After Replacing Spark Plugs?
3 Answers
Newly replaced spark plugs causing idle shaking may be due to damaged or broken ignition wires during the replacement process, leading to abnormal ignition. Alternatively, it could result from installing spark plugs of a different model. If the issue is confirmed to be related to the spark plugs, simply replacing them with the correct model should resolve the problem. Below is additional information: 1. Function of Spark Plugs: Spark plugs, commonly known as sparkers, are responsible for discharging the high-voltage pulses sent through the ignition wires. They create an electric spark by ionizing the air between their electrodes, igniting the air-fuel mixture in the cylinder. 2. Main Types of Spark Plugs: Standard spark plugs, extended insulator spark plugs, electrode spark plugs, seat-type spark plugs, pole-type spark plugs, and surface-gap spark plugs. Spark plugs, in conjunction with the ignition and fuel supply systems, play a crucial role in determining engine performance.
Last time I changed the spark plugs on my old car, I also encountered an idle shaking issue. Upon inspection, I found that the ceramic part of the spark plug had gotten engine oil on it during installation, causing uneven electrical leakage during ignition. Another common issue is the electrode gap of the new spark plugs not being adjusted correctly. The factory requires 0.8 mm, but if you install one with a 1.0 mm gap, the ignition energy becomes unstable. I recommend removing the new spark plugs, thoroughly cleaning them, and then measuring the gap. While you're at it, check if the ignition coil connectors are securely plugged in—last time, my friend's car shook because one of the coil connectors wasn't fully seated. All this should be done when the engine is cold; removing parts when hot can easily strip the threads. Finally, remember to tighten them with a torque wrench—too loose and they'll leak, too tight and the ceramic may crack.
After over a decade of car experience, I've found that post-spark-plug-replacement shaking mostly stems from compatibility issues. First, check if the model is correct – using regular spark plugs in a turbocharged car will definitely cause shaking. Secondly, the heat range must match; upgrading to a higher heat range increases carbon buildup and spark plug load. During installation, always clean engine oil from the cylinder holes as residual fluid can cause instant misfires. It's best to run a computer diagnostic to read misfire data and identify the problematic cylinder. Last time my car shook, it was due to aging ignition coil rubber in cylinder #3 leaking electricity – the issue only surfaced when the wiring was disturbed during spark plug replacement. Remember, new spark plugs need a 50km break-in period; short-term shaking might resolve itself.
