The “secondary air filter” is actually a carbon filter to capture any hydrocarbon molecules that waft up from the cylinder when you shut the engine down. If you analyze the cycles in a 4-banger, you’ll find that at any moment there is always one cylinder on the intake stroke, with the intake valve open and the injector spraying. Thus, whenever you shut the engine off, there’re unburned hydrocarbons just past an open intake valve. The EPA now requires that they be prevented from finding their way into the environment. Thus, the carbon filter.
I removed my carbon filter as part of an induction system redesign I did that made it a ram air system feeding directly off of a “scoop” intake in the from bumper. My system is designed to prevent the possibility of water from being ingested even if I go through a puddle. Removal of the carbon filter will not “tripp a light” or cause an emissions failure, however it by itself will also not help performance one iota. Even my design is only effective at WOT and at speed. It makes a definite difference on the highway when I “punch it” to pass, or when accelerating to merge with traffic, but no difference “off the line”.
And yes, were my warranty not long-since expired it would have voided it. Any modification you do to the engine provides them with an excuse to disqualify warranty coverage for and engine-related failures.
Oh, and the CAI systems on the market are junk. They take the air typically from the same area as the original snorkle, and the only real benefit they offer is reduction of pumping losses at WOT by displacing original induction system components that have obstructions to the airflow with smooth piping. They do this at the expense of noisiness and the risk of screwing up the mass airflow sensor from the oil in th efilter they use.
- Any modification you do will provide them with an excuse to disqualify warranty coverage.
- make no changes unless and until you understand exactly what you’re doing and have realistic expectations for the results.
- be very, very wary of chips and reprogramming, as VDC has emphasized. Unless you know what you’re doing you can ruin an engine, and the people selling these things don;t necessarily care if you do. There’s lots of destructive rubbish on the market.