Air induction system removal

SULTAN · Mar 16, 2011

Good dat to all.

In the answer to a recent post of mine about exhaust popping, in part of one reply i recieved about removing the air induction system and fitting cover plates the following was said: Caution - removal will affect cat operation if cats are still in place, reducing effectiveness and possible life. Yet in another section of the reply refering to "capping the system" without cover plates, there is no mention of cat operation. Please tell me what cat stands for. Do only gen ll bikes have cats or does gen l also have them.

As i wish to remove my air induction system i would like to understand what cats are and what are their function.

Safe riding

SULTAN

Donal · Mar 16, 2011

The cat referred to is a catalytic converter - Cat Not sure when they started fitting cats, hopefully someone more knowledgeable will come along and advise you.

Don

ionbeam · Mar 16, 2011

The ending statement first: Running your FJR without the Air Injection system will do no harm to the catalytic converter under all normal operating modes. And now, the details...

The catalytic converter (cat-con or cat) is solely an emissions control device. The Gen I (2001 to 2005) FJR has a three way catalytic converter which is a honeycomb shaped block held in a cross-over chamber between the head pipes and the exhaust pipes. The Gen II has a similar catalytic converter. Being a three way emissions devise means that it reduces CO, HC and NOx to clean up the exhaust enough to meet stringent emission laws in some countries. The honeycomb is coated with platinum, palladium, and rhodium which are the active catalyzing agents that neutralize the bad exhaust components. The initial 'ligh-off' temperature of the cat-con is 400 to 600 degrees F, and it achieves normal operating temperature in the range of 1,200 to 1,600 degrees F.

The Air Induction system is active from the time a cold engine is started until the thermostat opens, then once the engine is warm the Air Injection is active only when the engine is idling. When the engine is cold the extra air that is injected into the exhaust stream reduces the HC load on the cat-con. If the exhaust gasses are very, very rich in unburned hydrocarbons for a very long time the cat-con can become coated which reduces its effectiveness. A test for this condition is to use a non-contact infra-red pyrometer (electronic thermometer) to measure the inlet and exit temperatures of the cat-con. A healthy cat-con, at operating temperature will typically have less than a 30 degree difference between the inlet and outlet temperatures. If a FJR has the Air Induction disabled but is normally ridden until the thermostat opens the cat-con will get hot enough to burn off any accumulated HC compounds.

The catalytic converter is just one element in the entire emissions system of the FJR. The Fuel Injection mapping and Fuel Cut-Off on deceleration plays a role in reducing hydrocarbons to the catalytic converter. When the engine is up to operating temperature, and the engine speed is in an operating band of roughly 3k rpm to 6k rpm and is being maintained fairly steady in this range the O2 sensor is used to keep the fuel injection operating in a 'closed loop' mode where the O2 sensor determines the final fuel injection trim. All these systems reduce the work load for the catalytic converter, making the air injection a non-critical system.