What Causes Weak Throttle Response After Vehicle Wading?

[MarcusFitz]

Due to water ingress causing damage to sensors or electronic control mechanisms around the engine. Below is relevant information about the throttle: Introduction: The throttle, also known as the "air valve" or "throttle valve," refers to the control device that regulates engine power. In piston aircraft engines, the throttle controls the carburetor's throttle valve opening to regulate cylinder filling volume, thereby determining engine output power. Causes and Solutions for Throttle Abnormal Noises: Carbon buildup in the throttle causing sticking requires throttle cleaning; wear of the throttle pedal support pin can be resolved by applying grease; poor installation of throttle cable (for electronic throttles, inspect the throttle pedal mechanism and throttle pedal sensor).

[LeAna]

Last time my car went through deep water, the throttle became extremely weak, and it took me a while to figure out why. If water rushes into the exhaust pipe and blocks the catalytic converter, the exhaust gets trapped inside. The more severe the blockage, the harder it is for the engine to breathe, causing it to roar without moving when you press the throttle. If the air filter gets soaked, it’s even worse—the engine feels like someone’s pinching its nose, starving for air and messing up the air-fuel mixture. In severe cases, water might even enter the cylinders, causing the engine to stall. In such situations, there’s only one solution—shut off the engine immediately and call for a tow. Trying to restart it could lead to severe engine damage like cylinder scoring, requiring a major overhaul.

[DiJude]

In all my years of repairing cars, nine times out of ten when the throttle feels weak after driving through water, it's because the catalytic converter is ruined. When the water level rises above the exhaust pipe and cold water hits the catalytic converter at several hundred degrees, the ceramic core immediately cracks into pieces. The debris clogs the exhaust passage, causing exhaust backpressure to skyrocket, making the throttle feel heavy and accompanied by a sputtering sound from the exhaust pipe. Even worse, exhaust gases can backflow into the engine, significantly reducing combustion efficiency and causing fuel consumption to spike. Never attempt to dismantle the exhaust pipe yourself for this kind of issue. Take it to a repair shop—they can use a borescope to check and determine whether the entire catalytic converter needs replacement.

[VanReagan]

Don't take a soggy throttle lightly after wading through water! New cars especially need to watch out for wiring failures. Just the other day, my neighbor's SUV drove like an old ox pulling a cart after getting soaked—turned out the crankshaft position sensor was waterlogged and malfunctioning. Once this part gets wet, its signals become erratic, leaving the ECU completely confused about crankshaft speed, messing up fuel injection and ignition. At best, you'll experience throttle lag; at worst, the car might just stall. And let's not even mention those oxygen sensors under the car—they go on strike the moment they get wet. Honestly, water damage to these electronic components is like dropping your phone in the toilet: even if it seems dry on the surface, it might throw a tantrum any day.

[SanDelilah]

Loss of throttle response after wading through water can be divided into two scenarios: If the water level exceeded the exhaust outlet but didn't submerge the air intake, it's likely a clogged catalytic converter - a repair shop might still save it. However, if the water rose above half of the wheel height and soaked the air filter, absolutely avoid touching the throttle! I've seen novice drivers stubbornly push through, only to hydro-lock the cylinders, resulting in repair costs exceeding tens of thousands. Key reminder: Never restart the engine if it stalls during water crossing! After the water recedes, first remove the air filter to check its dryness, then inspect the exhaust pipe for debris. Also, repeatedly pump the brake pedal as waterlogged brake pads will impair stopping power.