What Causes a Car to Stall When Releasing the Throttle?
2 Answers
Releasing the throttle and causing the car to stall can be attributed to issues such as clogged fuel injectors or carbon buildup in the throttle body. Below are the specific reasons for stalling when releasing the throttle: Fuel injector leakage or clogging: If the fuel injectors inside the engine leak or become clogged, or if there is a circuit malfunction or insufficient fuel injection, they may fail to spray fuel as instructed by the electronic control unit. This results in an overly lean or rich air-fuel mixture in the engine, causing some cylinders to malfunction and leading to engine stalling. Throttle body carbon buildup: The throttle body controls the intake of air into the engine. After air enters, it mixes with fuel to form a combustible mixture that powers the engine, functioning like a valve. During engine operation, a significant amount of exhaust gas is produced, some of which may enter the throttle body. Over time, if not cleaned, carbon deposits can form on the throttle body, increasing resistance to its opening and closing. This prevents normal air intake, disrupts engine operation, and often results in stalling.
Last time I drove my friend's old Lavida, I encountered the same issue—the engine stalling when releasing the throttle was terrifying. I focused on checking three key areas: First, the crankcase ventilation pipe behind the throttle body. If it's aged, it can leak air, causing the air-fuel mixture to become too lean and stall the engine. Second, the idle air control valve behind the air filter. If it's clogged with carbon deposits, it stops working—like having your throat choked, making it impossible to stabilize the RPM. Third, the condition of the fuel injectors. Too much varnish buildup can lead to insufficient fuel delivery. In my case, the ventilation pipe had a small crack, so I wrapped it with electrical tape as a temporary fix, and it actually held until I reached the repair shop. I recommend checking these areas first and cleaning the carbon deposits from the throttle body—it only costs a few dozen bucks. If the problem persists, you’ll need to check the fuel pump pressure, which requires a pressure gauge for testing.
