What are the possible causes of poor engine acceleration?
3 Answers
Causes of poor acceleration in automotive engines include: 1. Incorrect ignition timing; 2. Low fuel pressure; 3. Air leaks in the intake system; 4. Faulty throttle position sensor or mass airflow sensor; 5. Poor injector performance; 6. Malfunctioning exhaust gas recirculation system; 7. Weak ignition signal, etc. If the engine exhibits poor acceleration, the following inspections can be performed: 1. Perform self-diagnosis to check for fault codes. Issues with the mass airflow sensor, throttle position sensor, etc., can affect acceleration. Follow the displayed fault codes to identify the cause. 2. Check ignition timing. At idle, the ignition timing should be around 10-15 degrees. If incorrect, adjust the initial ignition timing. During acceleration, the timing should automatically advance to 20-30 degrees. If abnormal, inspect the ignition control system or replace the ECU. 3. Inspect the intake system for leaks. Measure intake manifold vacuum; at idle, it should exceed 66.7 kPa (500 mmHg). If too low, check all intake pipe connections, hoses, and vacuum lines for leaks. 4. Inspect the air filter. Clean or replace if clogged. 5. Check the throttle position sensor. At full closure, the idle switch should engage; when opening, it should disengage. Near full throttle, the full-load switch should engage. Adjust or replace as needed if abnormal.
The car feels sluggish, and when you press the accelerator, the engine seems to gasp for air. I’ve seen this issue countless times in the workshop. Common problems include a clogged fuel system—such as a dirty fuel filter or insufficient fuel supply from the pump—starving the engine; ignition system failures, like worn spark plugs or faulty ignition coils, leading to weak sparks; air system issues, where a dirty air filter restricts airflow or the mass airflow sensor sends erratic signals; unstable electronic control systems, with ECU module glitches or faulty sensor data; and mechanical problems, like a loose timing belt causing incorrect ignition timing. I recommend regularly cleaning filters and checking spark plugs. Otherwise, fuel consumption will spike, and the car might even stall on the highway, potentially leading to accidents. Owners of older cars should be especially cautious—get the ECU scanned with a diagnostic tool at the shop. A small investment can prevent major trouble.
Hey, I've encountered this issue with my manual hot hatch too – the throttle feels sluggish, and there are quite a few possible causes. Fuel system problems are common: clogged injectors from carbon buildup or unstable fuel pressure can lead to uneven fuel delivery and weak acceleration. Ignition system faults like leaking ignition coils or excessive spark plug gaps reduce combustion efficiency. Air intake issues such as sticky throttle valves or intake leaks restrict airflow. Faulty O2 sensors or throttle position sensors can mislead the ECU. Mechanical wear like piston ring degradation causes compression loss. Modified exhaust or turbocharged cars are more prone to these issues. Regular throttle body cleaning and fuel additives prevent most problems. This is dangerous during highway overtaking – pull over immediately for inspection or towing.
