What Causes the Engine to Shake Every Few Seconds at Idle Speed?
3 Answers
Engine shaking every few seconds at idle speed can be caused by the following reasons: Misfire: Check the condition of the spark plugs, high-voltage wires, and ignition coils. Poor performance of the ignition system or weak spark plug firing can lead to this issue. Severe carbon buildup: The most common cause of engine shaking is excessive carbon deposits on the throttle body or fuel injectors. When there is too much carbon buildup inside the engine, the gasoline sprayed by the cold-start injector is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts. Only when the carbon deposits become saturated with gasoline can the engine start easily. After starting, the gasoline adsorbed on the carbon deposits is drawn into the combustion chamber by the engine's vacuum, making the air-fuel mixture too rich.
I've encountered this issue quite a few times. The engine jerks every few seconds at idle, most commonly due to aging or dirty spark plugs causing uneven combustion from an inefficient ignition system. Clogged fuel injectors are another frequent culprit - unstable fuel supply leads to inconsistent combustion. Then there's the intake system; problems like a neglected air filter or vacuum hose leaks can disrupt the air-fuel mixture and cause shuddering. Don't underestimate these symptoms - they accelerate engine wear. Left unaddressed, fuel consumption increases and may damage other components like sensors. For DIY solutions, start by replacing spark plugs (detailed tutorials are available online), but if it feels too complex, visit a professional shop. Safety first - maintaining engine health saves significant repair costs.
My car just developed this issue last month - the idle speed would slightly fluctuate every few seconds, which was really annoying. After checking, I found the fuel injectors were heavily carbon-fouled, and the problem smoothed out after cleaning. It could also be worn-out spark plugs or a clogged air filter - the former causes intermittent ignition while the latter restricts air intake. Another possibility is unstable fuel pump pressure leading to uneven fuel delivery. I DIY-replaced these parts myself, spending just a few hundred bucks to fix it. My advice: don't panic when encountering similar symptoms. First inspect simple items like pulling spark plugs to check their condition or cleaning the air filter. Delaying repairs will significantly reduce driving comfort and increase engine strain - you wouldn't want to break down halfway someday. Always assess your capability before DIY attempts - safety comes first.
