Changing the oil filter and spark plugs on your Toyota Tacoma is great
maintenance but I'm afraid it will not fix a lean fuel condition. Changing
the fuel filter on the other hand (only if the current one is plugged and
restricting fuel flow) will help fix a lean fuel mixture. The most important
thing here is to find out why your vehicle is running lean. The problem can
either be mechanical or electronic. If mechanical we recommend inspecting
anything that might cause the fuel system to run lean, i.e.. vacuum leaks,
disconnected hoses, restricted fuel filter. If the problem is determined to
be electrical, the first component we'd suspect is the oxygen sensor. If
this doesn't work, the next component which could be the culprit would be
the mass air flow sensor.
Keep in mind with a computer controlled engine such as this, there are
several components which play a role in determining fuel ratio. Along with
the O2 (Oxygen Sensor), components such as the TPS (Throttle Position
Sensor), ECT (Engine Coolant Temperature Sensor) and MAF (Mass Air Flow
Sensor) sensors send vital engine information to the computer which is used
to determine proper air to fuel ratio. If any one of these components are
defective they can alter the fuel delivery program. A smog service station
would be able to diagnose each component and report it's condition.
