What is the reason for an Audi stalling and restarting without cause?
4 Answers
Specific reasons are introduced as follows: 1. The spark plug loses its ignition capability. 2. Throttle failure. 3. Carbon deposits: Carbon deposits can cause incomplete combustion of gasoline, leading to engine shaking issues. Additional information: 1. The specific effects of engine carbon deposits on a car are as follows: (1) Reduced engine power, meaning uneven and gradually decreasing power output, in other words, the car becomes less powerful over time. (2) Increased fuel consumption, adding to the economic burden. (3) Difficulty in cold starts, meaning the car is hard to start. (4) Severe carbon deposits in the combustion chamber can also cause cylinder knocking, noise during low-speed acceleration, damage to the piston and crankshaft, and high engine temperatures, severely affecting car safety. (5) Exceeding emission standards, not only failing annual inspections but also directly increasing environmental pollution hazards.
I've also experienced sudden engine stalling with my Audi, but it returned to normal after a restart. The most common cause is ignition system issues, especially aging ignition coils in older models. When vibrations increase during high-speed driving, poor contact can occur, leading to cylinder misfires and immediate engine shutdown. Additionally, severe spark plug carbon buildup can cause this. During cold starts, unstable fuel injection combined with reduced ignition efficiency due to carbon deposits can stall the engine. After restarting, the system readjusts and works fine, but the issue may recur. It's recommended to check the ignition coil connectors and spark plug condition, and also inspect whether the mass airflow sensor is clogged with oil residue – a dirty sensor can affect air-fuel mixture concentration and cause engine failure.
I experienced two instances of unexplained engine stalling while driving my A6, and everything was fine after restarting. After some research, it's likely a fuel system issue. If the fuel pump relay has poor contact, the fuel pressure can suddenly drop to zero, causing the engine to stall. Alternatively, if the fuel filter is clogged, insufficient fuel supply during heavy acceleration can also lead to stalling. Poor-quality gasoline with excessive impurities can clog several injectors, potentially causing sudden shutdowns. Upon restarting, the fuel pump resumes operation, temporarily restoring fuel supply, but the underlying issue remains. Focus on inspecting the fuel system, especially for vehicles that haven't had their fuel filters replaced in 70,000 to 80,000 kilometers, as a clogged filter is a common culprit for this problem.
Last year, my friend's Q5 also had this issue, and it was resolved by turning off and restarting the engine. I checked the fault codes for him and found that the crankshaft position sensor was intermittently failing—this part is installed at the bottom of the engine and is prone to oil sludge buildup. Abnormal signals from the sensor can cause the ECU to misjudge the crankshaft position, leading directly to fuel cutoff and engine stalling. Another possibility is worn-out generator brushes, which can cause voltage instability and crash the electronic control system. Audi has many electronic systems, and any sensor acting up could potentially cause stalling. I recommend connecting a diagnostic scanner to check historical fault codes, with a focus on fluctuations in the engine data stream.
