When we talk about the importance of any automotive filter, it’s usually in the context of the physical protection that the filter provides, whether it be for the occupants of the vehicle or the engine. And make no mistake, the level of physical engine protection that the air filter provides is very important as the primary function of the filter, but it’s not all that matters anymore. The engine air filter of any vehicle powered by an internal combustion engine is a relatively small, seemingly insignificant part, that has a massive impact on modern engine performance. In fact, the engine air filter found in the air intake system of modern vehicles is more important than it’s ever been.
Engine Air Filter Impact on Performance
Sometime around the early to mid 1980s high-end automakers began using computers in the cars they manufactured. The so called “computers” used were really just small electronic control units designed to communicate with a variety of sensors positioned throughout the car. By 1995 almost all cars rolling off of every assembly line were equipped with some form of electronic control unit and a multitude of sensors which provided feedback for them to act on. Fast-forward a quarter century and we find that vehicle electronics and engine management have become significantly more complex. The ECUs of the mid-90s have evolved to function on levels comparable to a conventional personal computer. The names and acronyms they’re called by might vary from one automaker to the next, but they all manage the same types of distributed systems – braking control, chassis control, body control, safety, powertrain control, and engine control.
Every Calculation Made by the Engine Control System Is Affected by Intake Airflow
The engine control system is responsible for how the engine runs – How powerful it is, how efficient it is, how it idles and how responsive the throttle is. The engine air filter has a direct impact on the engine control system because its performance affects the readings and data that the mass airflow sensor sends to the ECU. The signals that the mass airflow sensor sends, enable the ECU to calculate the stoichiometric (ideal) air-fuel ratio (AFR) for optimal combustion within the chamber. Without the ideal AFR, the engine isn’t going to run the way it’s supposed to. To further complicate matters, downstream from the engine air filter and mass airflow sensor there are usually other critical components impacted by variations in airflow such as the Intake Air Temperature Sensor (IAT), the Idle Air Control Actuator (IAC) and the Manifold Pressure Sensor (MAP). Less air will result in less fuel released by fuel injectors, so fuel economy probably won’t suffer, but power will be affected, idle will be affected, efficiency will be affected, and throttle response will be affected.
Dirty Air Filter Can Lead to Critical Problems Elsewhere
Neglecting the engine air filter for too long or using a filter that doesn’t meet OE standards could lead to problems elsewhere, and it usually starts with damage to the mass airflow sensor. The mass airflow sensor is typically positioned in close proximity to the air filter – sometimes just a few inches away, inserted into the intake pipe. This location is necessary in order to get the readings the ECU needs, but it also makes the mass airflow sensor vulnerable to damage from dust, debris or anything else that gets by the filter. Another potential hazard for the mass airflow sensor is the use of an air filter that doesn’t meet OE standards – one problem is filters that use media infused with oils. It is claimed that the addition of the oil helps improve efficiency by making the media stickier. Unfortunately, for the oil to be effective it has to be applied liberally and often the oil is applied so liberally that it can’t evaporate and winds up on the mass airflow sensor. In fact, oiled air filter media is the leading cause of death for mass airflow sensors. This isn’t to say that all oil-infused filters are going to kill the mass airflow sensor, but it’s a good example of how sensitive these components are to outside contaminants.
Symptoms of a faulty mass airflow sensor can manifest in a variety of ways which might resemble low compression, vacuum leaks, or fuel delivery problems. Sometimes the engine might be hard to start or turn over, the engine might stall, might have a rough idle or jerky throttle response, misfires or excessively rich or lean idling. Think about all of the other sensors and actuators that are affected by what the mass airflow sensor is doing – All of these issues could be trickle-down effects of engine air filter neglect, and all will undoubtedly lead to much bigger problems if left unchecked. For example, unresolved misfires can lead to cracked heads and worn-out piston rings, while running too lean can lead to engine failure.
Regular Maintenance with A High-Quality Air Filter Is the Key
Modern vehicle engine technology is exponentially more complex than the machines our Grandparents were driving around in their youth. With the array of distributed systems that manage every function of the vehicle they can be much more expensive to fix as well. The best way to mitigate these potential issues is to stay on top of engine air filter maintenance. Replace the engine air filter at regular intervals, even if it doesn’t appear terribly dirty – The risk simply isn’t worth it. Just beware that all air filters are not created equal when it concerns modern engines. It’s very important to make sure to replace the old dirty filter with an air filter that is engineered and constructed to original equipment specifications. Any air filter constructed with different media, different number of pleats, additives such as oil, etc. could affect air flow and dirt holding capacity and have a negative long-term impact on critical components downstream.