exhaust system
04-12-2012, 11:53 PM
#1
Senior Member
Thread Starter
exhaust system
I just came across this information on Fords technician training site. The update this year has a lot of information with some good descriptions. I wish I could simply post the page but obviously that is not allowed by Ford. So here is a few things I found interesting.
What does the air pump do? First is a better explanation of how the catalytic converter actually works. To explain simply, the basic operation of the cat is create a chemical reaction to reduce the amount of pollutants in the exhaust. This reaction creates heat and requires high amounts of oxygen to occur. This is where our air pump comes in. It ads oxygen rich air to the stream to induce the chemical reaction. Depending on vehicle design, the pump will divert air to a second hose downstream or in most of our trucks, out to the atmosphere via the funny shaped muffler that looks like its missing a hose mounted on the passenger side wheel well (on the 5.0 anyway). This happens when the engine is laboring or extremely hot, during WOT, deceleration or long periods of idle.
Why do I have 2 catalytic converters? There are basically 4 types of cats. 1) Conventional Oxide Catalyst oxidizes HC and CO 2) Three Way Cat works on HC and CO as well as NOx 3) Light Off Cat is designed to operate with minimal warm up. It has little heat sink and works close to the manifolds in the high heat area. 4) Reduction-Oxidization is designed for heavy duty operation on mid to heavy trucks (8500-14000 lbs)
Trucks with dual inline cats use the LOC up front close to the manifold to operate during warm up. It is then followed by a COC or TWC to finish the job when it reaches operating temperature.
What does the air pump do? First is a better explanation of how the catalytic converter actually works. To explain simply, the basic operation of the cat is create a chemical reaction to reduce the amount of pollutants in the exhaust. This reaction creates heat and requires high amounts of oxygen to occur. This is where our air pump comes in. It ads oxygen rich air to the stream to induce the chemical reaction. Depending on vehicle design, the pump will divert air to a second hose downstream or in most of our trucks, out to the atmosphere via the funny shaped muffler that looks like its missing a hose mounted on the passenger side wheel well (on the 5.0 anyway). This happens when the engine is laboring or extremely hot, during WOT, deceleration or long periods of idle.
Why do I have 2 catalytic converters? There are basically 4 types of cats. 1) Conventional Oxide Catalyst oxidizes HC and CO 2) Three Way Cat works on HC and CO as well as NOx 3) Light Off Cat is designed to operate with minimal warm up. It has little heat sink and works close to the manifolds in the high heat area. 4) Reduction-Oxidization is designed for heavy duty operation on mid to heavy trucks (8500-14000 lbs)
Trucks with dual inline cats use the LOC up front close to the manifold to operate during warm up. It is then followed by a COC or TWC to finish the job when it reaches operating temperature.
