Engine Performance problem
2001 Toyota Corolla 4 cyl Front Wheel Drive Automatic 180000 miles
Auto appears to be fuel starved at takeoff. Had several mech. Look at it but noone has come up with remedy. Replaced plugs and ox sensor. No help. Auto now seems to stumble when acceloerator is pressed at higher speeds and does not seem to shift correctly. Car runs great at highway speeds and does not use oil and still gets teriffic milage. Problem seems to be getting worse and it is hard to start at times.
Possible Causes of Engine Hesitation or Stumble: Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)
Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include: Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires