Fuel Injectors for 1985–2010 Toyota 4Runner

How long do 4Runner injectors last across these engine families?

The 22R-E and 3VZ-E injectors typically fail between 110,000 and 140,000 miles due to side-feed design and heat exposure. The 5VZ-FE 3.4L usually makes it to 130,000-150,000 before spray patterns degrade. The 1GR-FE 4.0L and 2UZ-FE 4.7L engines run higher pressure and often need replacement around 120,000-160,000 miles. Short trips under five miles and high ethanol content accelerate wear on all generations. If you're past 100,000 on the original injectors and seeing fuel trim corrections above +8% at idle, start planning replacement.

Can I replace 4Runner injectors myself or does this need a shop?

The 22R-E four-cylinder is straightforward—remove the cold-start injector, unbolt the fuel rail, swap injectors, done in two hours. The 3VZ-FE V6 requires upper plenum removal but stays manageable for a home mechanic with basic tools. The 5VZ-FE 3.4L is similar. The 1GR-FE 4.0L V6 needs intake manifold removal—plan half a day. The 2UZ-FE 4.7L V8 is the worst: you're pulling the entire upper intake plenum assembly, disconnecting throttle cables, and dealing with twenty vacuum lines. Budget four to five hours if you've done it before, six to seven if it's your first time.

What diagnostic steps confirm bad injectors versus other fuel system issues on a 4Runner?

Start with fuel pressure—should read 38-44 PSI on 22R-E, 41-46 PSI on 3VZ-FE and 5VZ-FE, 44-50 PSI on 1GR-FE and 2UZ-FE at idle. If pressure is in spec but you have P0171/P0174 lean codes, check for vacuum leaks at the intake gaskets first—common on high-mileage 5VZ-FE engines. Pull spark plugs and look for one or two that are cleaner than the others, indicating a lean cylinder from weak injector spray. You can also run a cylinder contribution test with a scan tool—if one cylinder drops less than 75 RPM when disabled, that injector isn't flowing enough fuel.

Why do 3.4L 5VZ-FE 4Runners show lean codes even with new injectors?

The 5VZ-FE is an older port-injection design that builds carbon on intake valves over time. That carbon chokes off airflow into certain cylinders, which throws off the air-fuel ratio the ECU expects to see. You can install brand-new injectors and still pull P0171 or P0174 because the MAF sensor reads one airflow value but restricted cylinders are actually getting less. The fix is walnut-blasting the intake valves or running a strong intake cleaner every 30,000 miles. This engine also has a known issue with the lower intake manifold gasket leaking and causing false lean codes—check for vacuum leaks there before condemning injectors.