Frequently Asked Questions Ask APW
What is a true Mitsubishi Galant high-flow catalytic converter, and is it legal to use it?
Answer: A high-flow catalytic converter, as the name implies, allows exhaust to flow through a larger area and thus flow faster than in an OEM catalytic converter. It is regarded as being more effective than a regular catalytic converter because of its ability to increase power by increasing exhaust flow. When catalytic converters first came out, they had beads placed inside a housing over which the exhaust gas got converted and flowed out through the exhaust pipe. A honeycomb redesign for catalytic converters came out much later and was initially called a "high-flow" catalytic converter. The honeycomb design was soon used by most manufacturers, however, and although it became common practice, it is pointless to call them "high-flow." A true high-flow catalytic converter uses an oversized block of material, has larger inlet and outlet tubes, and has a longer tapered section. It is legal in all states except in California.
What is the correlation between a clogged catalytic converter and bad fuel economy?
Answer: Although there is no way to physically check if a catalytic converter is clogged, a noticeable drop in gas mileage is a telltale symptom. A clogged catalytic converter increases the pressure in the exhaust--imagine exhaust gas being pushed through a space that's smaller than it normally flows through. With the engine doing this extra job, it will not be able to perform its normal functions properly. This adversely affects the miles per gallon the vehicle will achieve.
What is the simplest way to check if a catalytic converter has failed?
Answer: Aside from a drop in gas mileage, a failed catalytic converter can also cause little or no power when accelerating. These are simple observations that can be done by the car owner to correctly diagnose a failed catalytic converter. Alternately, the catalytic converter can be detached and then shaken--if it rattles or produces a clanking noise, the honeycomb structure inside must have become brittle and cracked.