Most modern EFI engines have a Mass Air Flow (MAF) sensor located in the air intake of the engine. This is the device that measures how much air is coming into the engine so that the computer can determine how much fuel it needs to inject. While the MAF sensor does not directly measure the actual flow rate of air, it measures the density. Air density changes with temperature, altitude and forced induction (supercharger/turbo applications), making density more important than air volume flow rate.
There are two main types MAF sensors- hot wire and cold wire. A hot wire MAF sensor uses a platinum wire located in the path of air flow, which is heated using specific voltage. As the air passes over the hot wire, it is cooled, decreasing the wire’s resistance to voltage. The engine control module (ECM) measures this change and alters the tune accordingly. The other type is a cold wire sensor. These are commonly found in GM engines. These sensors use both a hot wire and a cold wire, where the cold wire functions as a reference for the hot wire.
Because these sensors are directly exposed to the air, they pick up contaminants that alter their readings, which lead to rough running conditions. You can’t use carburetor or brake cleaners on a MAF sensor, as the chemicals in those cleaners can destroy the delicate sensors. Instead, a special MAF sensor cleaner is required.
CRC MAF Sensor Cleaner is specifically designed to remove oil, dirt, fibers and dust from the sensor without damage. The chemicals used are hexane-based, which evaporate quickly without the use of alcohol. A clean MAF sensor is a happy MAF sensor. The process is quite simple and can be completed in about 10 minutes.
First, NEVER use MAF sensor cleaner with the engine running or even with the key in the run position. This can cause major damage to the sensor. With the key off, unplug the sensor.
Next, remove the air intake tubing and then remove the MAF sensor.
Place the MAF sensor on a towel to catch the runoff. Insert the plastic straw into the nozzle on the can and spray the interior of the housing with 10-15 blasts. You need to cover the hot wire(s) and plate. Be very careful to not touch the wires with any object, including the straw. The wires are quite delicate.
Spray all sides of the sensor and housing, including the connectors.
Reinstall the sensor into the car and allow a few minutes for the chemicals to evaporate before starting the engine.
It is a good idea to clean the MAF sensor every time you change or clean the air filter. A clean MAF sensor can restore 4-10 horsepower to the wheels, which is a significant number for just cleaning a sensor.
Warning: Do NOT use any MAF sensor cleaners on Karman-Vortex style air flow sensors, which are typically found in Toyota Supra turbos, Mitsubishi (including the DSM rebadged Eagle Talon and Plymouth Laser), and most Lexus engines. These special Karman-Vortex sensors use highly sensitive components that cannot be cleaned and any attempt to do so may cause serious damage to the MAF sensor. When in doubt, just leave it alone.
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A life-long gearhead, Jefferson Bryant spends more time in the shop than anywhere else. His career began in the car audio industry as a shop manager, eventually working his way into a position at Rockford Fosgate as a product designer. In 2003, he began writing tech articles for magazines, and has been working as an automotive journalist ever since. His work has been featured in Car Craft, Hot Rod, Rod & Custom, Truckin’, Mopar Muscle, and many more. Jefferson has also written 4 books and produced countless videos. Jefferson operates Red Dirt Rodz, his personal garage studio, where all of his magazine articles and tech videos are produced.