1994 Toyota 4Runner engine stumbles a little

1994 TOYOTA 4RUNNER
191,000 MILES • 6 CYL • 4WD • MANUAL
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FLAVIOPARTIDA
  • MEMBER
  • 1 POST
The engine on my 4 runner stumbles a little when pressing the accelerator, then it smoothes itself out when the rpm goes up on its own without me pressing harder on the pedal. I"ve only changed the plugs, cap and rotor. Any suggestions on any other things i need to pay attention to?
Jan 17, 2010 at 6:54 AM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
Check and test the following:

Oxygen sensor
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
Cap and Rotor
Jan 17, 2010 at 7:38 AM
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