Bucking in the Morning

Tiny
YUKON5
  • MEMBER
  • 1990 TOYOTA 4RUNNER
  • 6 CYL
  • 4WD
  • MANUAL
  • 218,000 MILES
90 4 runner with 218,000 miles, original clutch. In the Morning truck bucks'' after down shifting and it also feels like minor bucking once up to speed. Fuel filter changed out around 150,000. In the afternoon all bucking goes away and the truck runs great. Any ideas?
Thursday, August 11th, 2011 AT 4:12 PM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Could be caused by one of the following below

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note:If it doesn't apply disregard it and keep testing.
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Thursday, August 11th, 2011 AT 5:50 PM

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