Ah yes, the lowly air filter. One of the easiest bolt on performance upgrades and one of the easiest maintenance items to overlook.
We have seen it all, and if you live anywhere near a forest or meadow you can almost be sure that sooner or later a critter will take up residence in this perfect little compartment.
It’s insulated. Completely weather-proof. large and roomy for the whole family. You just need to be able to put up with the occasional vortex of death.
The above video was taken after the customer complained of an extremely high idle (around 4,000rom!) and after seeing all the rodent droppings under the hood, Marty suspected that there was part of a rat nest stuck in the throttle body, holding it open. This is not the first time we have seen something like this, but one of the first live ones, and definitely the first time one jumped out at us!
If you have ever shopped for vehicle mods, you have heard of K&N air filters and their Million Mile Warranty. If you haven’t heard of them they are a company that makes a washable, re-useable filter that lets more air into your engine and lets the engine basically breathe easier. K&N was I think the first company to do this, but now there are dozens of products that offer performance air filters. They work good at letting more air into the engine (in the hope that the engine computer can add the corresponding amount of extra fuel for more power), but absolutely do not filter the air better.
The filter element is made of cotton and if you hold it up to the light you will see tiny holes in the media. Trucks that get driven in dusty conditions that have these filters need to have a pre-filter or tiny dust particles will enter the engine and wear out the rings and cylinder walls prematurely. A pre-filter is basically a nylon bag that goes over the filter, and restricts air flow since it is another layer for the air to go through. Sounds counter productive, huh?
Another problem with these filters is the fact that since they are made of cotton, and are re-useable, they need to be oiled to have the dirt and dust stick to them. This oil then gets on the Air Flow Meter if your car or truck has one. This oil and the tiny dust particles that the filter didn’t catch get stuck on the sensor element. These elements have a small current flow through them and depending on how much air flows past them, the current is modified and the computer can tell how much air is going into the engine. This information is critical on modern engines. It is the the single most important sensor to a properly tuned engine.
If that tiny little wire gets dirty, it’s like wearing a down jacket and a wind breaker. The sensor is essentially insulated from the air it is supposed to meter! If it is dirty symptoms like pinging, overheating under load, misfire, and check engine illumination will plague you until it is cleaned or replaced. There are many approved cleaners on the market meant to deal with this problem, as it happens even if the filter is a stock element that does the best filtering job possible.
Whenever you shut off your engine, unburned fuel and oil vapors are left in the intake manifold, and like our coastal fog, will condense on the coldest part of the intake first- the sensor and throttle body. It takes many, many miles for this to happen under stock conditions, however. If you attempt to clean your own Air Flow Meter make sure you use a product deigned for the job, or you will damage the sensor!
