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. This is a very important sensor that typically does its job consistently without issues, but that doesn’t mean it can be ignored forever. It is best to get ahead of any problems by giving your MAF sensor a little attention. Here’s how to clean your MAF sensor for better performance and better overall engine health.
What Is A Mass Air Flow Sensor?
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 cleaner or brake cleaner on a MAF sensor, as the chemicals in those cleaners can destroy the delicate sensors. You need special MAF sensor cleaner which is specially formulated to clean without leaving behind any harmful residue. The same cannot be said for carb cleaner or brake parts cleaner, so leave them on the shelf. As a bonus MAF sensor cleaner is also excellent for cleaning other sensitive electronics.
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.
How To Clean A Mass Air Flow Sensor
We’re cleaning the MAF on a 2004 Ford Mustang with a 4.6L V8 engine, but these steps are fairly universal and apply to most vehicles.
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. Take a picture of the intake assembly with your smart phone before taking anything apart so you can reference it later when putting everything back together.
With the engine off and the ignition key removed it is now safe to unplug the MAF sensor. You may need to squeeze the tabs on the sensor plug and wiggle it to allow removal. The key is to be gentle as sensor plug plastic can get brittle over time due to exposure to extreme temperatures.
Next, remove the air intake tubing and then remove the MAF sensor. Depending on your vehicle you may need to disassemble parts of the intake like the air inlet or resonator in order to free up the MAF sensor.
Place the MAF sensor on a towel to catch any MAF cleaner runoff. Put on safety goggles to protect your eyes as the cleaner is under pressure and can splash back in your face. Insert the plastic straw into the nozzle on the can and spray the interior of the housing with 10-15 sweeping blasts. You need to coat the hot wire(s) and plate with MAF cleaner. 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 inside and the outer housing, including the connectors. Give everything a good spritz.
Let the MAF sensor sit on the towel for a minute to dry. Then reinstall the sensor into the car being careful to put everything back the way it was (refer to your photo if necessary). Allow a few more minutes for the chemicals to finish evaporating 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. If you have a reusable air filter that is oiled you will definitely want to clean the MAF sensor with every air filter cleaning.
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. There is no reliable method for a DIYer to clean a Karman-Vortex style air flow sensor and any attempt to do so will render it useless. 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.