What Causes Engine Idle Shaking and Stalling on Rainy Days?

[Charles]

There are many reasons that can cause unstable engine idling and easy stalling, such as air intake system leaks, low fuel pressure, clogged air filters, injector atomization leaks, improper idle adjustment, faulty spark plugs, air flow meter malfunctions, etc. Below is extended information about idling: 1. Introduction: Idling is an operating condition of a car where the engine runs in neutral gear. The engine speed during idling is called idle speed. Idle speed can be adjusted by modifying the throttle opening size, etc. Idling means the engine is "producing power without doing work." 2. Normal Idling: When the vehicle is in park and the engine is started, the minimum stable operating speed is called parking idle (the process where the engine transitions from cold idle state to normal operating temperature idle state is called warm-up or heating).

[Jess]

I've been driving for over thirty years and have experienced idle stalling in rainy conditions several times, mainly due to moisture infiltrating the ignition system. If the spark plugs get damp or age, ignition becomes unstable, causing the engine to shake or even shut down. If there are gaps in the high-voltage wires, rainwater can seep in, leading to leakage or short circuits. Water in the intake pipe can also disrupt the air-fuel mixture, resulting in abnormal combustion. I remember once stalling on the roadside during a heavy rain—upon inspection, I found the high-voltage wire cover was loose, allowing rainwater to seep in. Since then, I've made it a habit to regularly check these components and replace aging seals promptly. When parking in the rain, I always look for sheltered spots to avoid prolonged exposure of the engine to rain. Safety comes first—engine shaking isn't just annoying, it can also lead to accidents, so it's best to address the issue early.

[Connie]

Dealing with these issues every day at the repair shop, stalling and rough idling in rainy weather are mostly caused by water ingress in ignition components. When spark plugs get damp, they fail to ignite, causing the engine to shake due to incomplete combustion. Water accumulation in cracks of high-voltage wires or ignition coils can cause short circuits, extinguishing the spark. A soaked air filter leads to insufficient air intake and an imbalanced air-fuel mixture, also making stalling likely. Quick fix: Start the car to assess the situation, then check if the spark plugs are dirty and if there's any leakage at wire connections. It's advisable to avoid driving through deep puddles in the rain and to cover the engine hood when parked. Replacing high-voltage wires isn't costly but can prevent major overhauls.

[MarianaMarie]

This issue really freaked me out! My car suddenly shook like an earthquake and stalled while idling in the rain - so dangerous! After checking online, it's probably because rainwater got into the ignition system, causing spark plug misfire or high-voltage wire leakage. A wet air filter can also suffocate the engine. Now I know: try to avoid parking outdoors for too long, and inspect components promptly after rain. If it happens, stay calm and pull over slowly. Safety should be prioritized - don't wait until something major occurs.