Changing an air filter is one of the easiest maintenance tasks you can do on your Outlander, and it's also one of the most important. Using the right filter and replacing it when needed can ensure your Mitsubishi's engine will remain reliable while delivering plenty of power and low fuel consumption.
What Does an Air Filter Do?
An internal combustion engine works by drawing in air mixed with fuel, squeezing it into a tight space, and igniting it. We're all familiar with how much fuel this uses since we have to pay for it, but most of us don't think of how much air is needed for this process.
On average, your Mitsubishi's engine is mixing 12 to 13 parts oxygen with one part gasoline. Oxygen is only part of the air, so it takes significant amounts of air to get the right ratio for ignition. Even when idling, the motor is drawing in hundreds of cubic feet of air every minute.
At that rate, if a tiny amount of dirt is drawn in with that air, it builds up in a hurry. Once inside the engine, it can scratch cylinder walls, dirty the oil, and ruin sealing surfaces.
How Does an Air Filter Work?
A modern filter is made up of multiple layers of fibers. Going from the surface of the filter to the backing mesh, these fibers get smaller and smaller.
As air passes through, dust is captured by these fibers, starting with the largest particles at the surface. By the time the air exits the filter and enters the intake manifold, it's almost perfectly clean. The effects are obvious when looking at the air box: the section before the filter is usually dirty while the section after the filter will be spotless.
Once a fiber is holding a dust particle, it's effectively closed. Eventually, enough fibers are filled that they can restrict airflow.
What Happens If My Air Filter is Dirty?
Imagine going on a jog, but only being allowed to breath through a straw. That's basically what happens when your engine has to do if you drive around with a dirty filter.
If most of the fibers in the filter are clogged, there's only a small area where air can be drawn through. When the intake valves open, the piston moves down, drawing air from the intake into the cylinder. With such a small space to draw air, it takes more force to move the piston, resulting in higher pumping loses. This increased engine load reduces the power available to move the vehicle while increasing increase fuel consumption.
How Often Do I Need to Replace the Air Filter?
Mitsubishi recommends installing a new filter every 30,000 miles or 24 months. If you drive in severe conditions, the filter should be inspected every 15,000 miles or 12 months and replaced as necessary.
What counts as “severe conditions?” In this case, it means driving your vehicle on dirt roads. The added dust means the pores inside the filter get filled up faster. Of course, if you live here in Arizona, there's another way you can experience these conditions: dust storms. If you drive your Outlander through one, the filter can be saturated pretty quickly. It's a good idea to check your crossover's filter afterward to make sure it isn't completely coated.
What's the Best Air Filter for My Outlander's Engine?
The best filter is an Original Equipment Manufacturer (OEM) replacement. These filters are designed and manufactured by Mitsubishi, which means they were developed and tested alongside the motor to deliver the optimum balance of performance and filtration. While there are other options on the market, each design has some serious disadvantages.
“Performance” filters let more air in, but the only way to get more air into the engine using the same size filter is by increasing the size of the openings in the filter medium. That means more dirt can pass through, which increases engine wear. Likewise, standard aftermarket filters will cut corners on the filter medium, reducing the number of layers and density. The result is less effective filtration and a shorter lifespan.
Reusable filters use a foam filter element saturated in oil to capture dirt. This is less effective than a multi-layer filter, and some of the oil can make its way through the intake where it can get on the mass air flow (MAF) sensor. This can throw off the sensor's reading or cause the sensor to fail entirely. Without accurate readings the ECU can't accurately deliver the right amount of fuel to the engine, resulting in power loss, poor fuel economy, stalling and rough idling.
How Do I Replace the Filter on My Outlander?
Open the hood.
Locate the air filter box. On these vehicles, the air filter is either mounted in a conventional box, or it's mounted sideways. Looking at the radiator support, you'll see a vent connected to a large black tube. The box is at the end of this tube, next to the right side strut tower.
Release the two metal clasps on the top of the air filter box.
Separate the two halves of the filter box. The filter is in the center and can be lifted straight out.
Wipe out any dust inside the box, then insert the new filter. On conventional air boxes, the filter should fit flush with the bottom of the box. On sideways air boxes, the air filter has a plastic body that is sandwiched between the two halves. On these, the lip should fit onto the side of the air box next to the engine, while the other half slides into the air box.
Push the two halves of the box against the filter and latch the two clasps.
Where Can I Get an OEM Air Filter for My Outlander?
MitsubishiPartsOnSale.com offers genuine Mitsubishi Motors parts at discount prices. Our site lets you find filters based on your model, VIN and descriptions like “2.4l” and “Sport.” Already know the part number? You can type it into the search box and find it immediately. Not sure what you need? We have parts professionals on staff who can answer your questions.