1999 Honda Civic Engine rough a few minutes after start

1999 HONDA CIVIC
125,000 MILES • 4 CYL • 2WD • MANUAL
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LAOWU
  • MEMBER
  • 2 POSTS
Engine starts smoothly. After 2 or 3 minutes warm up. It stumbles if it leaves idle or it stumbles at a certain RPM when accelerate. There is no meter so I do not know what RPM is. But the symptom shows it stumbles at a certain RPM. It always stumbles a few seconds after acceleration on each gear. It runs sooth again when I changed to other gear. When the engine fully warmed it runs fine at any RPM. What would cause this?
Nov 1, 2009 at 12:26 PM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
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
Nov 1, 2009 at 8:21 PM
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