Bucking in the Morning

1990 TOYOTA 4RUNNER
218,000 MILES • 6 CYL • 4WD • MANUAL
Avatar
YUKON5
  • MEMBER
  • 1 POST
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?
Aug 11, 2011 at 9:12 AM
Avatar
RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 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.
Aug 11, 2011 at 10:50 AM
🔧 Tools & Auto Repair Parts
Find automotive tools, diagnostic equipment, and replacement parts for your next repair.
Shop on Amazon →
Paid affiliate link. As an Amazon Associate, we earn from qualifying purchases.
Add a reply
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.

Ask a new question

Frequently Asked Problems for This Vehicle