Time: 30-45min

Difficulty: moderate

Cost: $20-40

WHY

Throttle body, intake, injector and Mass Airflow Sensor cleaning. When parts get dirty, they don't do their job as well. 

Over time, grime can accumulate within the throttle body restricting airflow around the throttle plate. At lower RPM's, the limited airflow may cause the engine to surge or idle irratically often triggering trouble codes. To maintain proper airflow, it's a good idea to clean the throttle body inlet and plate from time to time. The same goes for the intake plenum. The smooth flow of air optimizes the atomization of the fuel and the efficiency of the burn. 

The Mass Air Flow (MAF) sensor, often paired with the Intake Air Temperature (IAT) sensor, tells the computer the volume and temperature of the incoming air. The computer uses this data as input for correct metering of the fuel. If the sensor is dirty, the computer isn't appropriately metering the fuel, again causing driveability problems and trouble codes. 

Fuel contains additives that lubricate and clean the injectors, but the quality of fuel isn't always a sure thing. Adding a chemical treatment to the fuel periodically can ensure their continued reliable function.

WHEN

The frequency required to clean these components will depend on how well you maintain your air filter. A clean air filter will prevent the buildup of drit and grime. In general, performing this service in sequence with a tune up (spark plugs) should be sufficient, so around 100,000 miles. 

METHOD

Watch the video below to see how this service was done on a 2007 Toyota RAV4. 

After performing the service, it's common for the engine to run rough or set a code as it burns off the now-loose grim and the raw fuel (cleaner) that has pooled within the intake. If this happens, start and run the vehicle at about 1/4 throttle until it clears. Use a scan tool or disconnect the battery to clear the code.