What Causes the Tachometer to Drop When Accelerating?

[LeNicole]

The specific reasons for the engine RPM dropping when accelerating are as follows: 1. Use an oil pressure gauge to measure the fuel system's oil pressure to check if there is any leakage in the fuel system. A slow leak in the fuel system can lead to low oil pressure when the engine is cold, making it difficult to start (common leakage points include the fuel injector and fuel pump); 2. Check if the carbon canister is severely clogged; 3. Inspect if there is an issue with the carbon canister solenoid valve. If the solenoid valve remains closed, gasoline vapor in the carbon canister will accumulate more and more, eventually filling the entire canister, with the excess vapor escaping into the atmosphere. Conversely, if the solenoid valve remains open, the air-fuel mixture in the engine intake will remain in an enriched state. Since the engine control unit has not yet activated the solenoid valve, it will not issue a command to reduce fuel injection, resulting in an overly rich mixture when the engine is hot, causing the engine to stall.