maybe you should have listened at school / try reading
As a vehicle burns petrol (...to push the piston down, which in turn spins the crank, ultimately moving the back wheel), the idea is to make the best use of the energy released. To do this well on a petrol engine, you need to get the right ratio of air to fuel.
The ratio can vary a bit depending upon conditions (temp, altitude, cruising, hard acceleration, etc.) but not by much. Any unburnt fuel produces undesirable emissions, waste resources, makes the oil dirty, washes off lube etc. To better control what's going on someone invented a sensor that's sitting in the exhaust gas flow, sniffing out what’s happening. Under the right conditions where gas flow is sufficient to get a reliable reading the vehicle goes in to a “closed loop” scenario where the fuel being injected is directly linked to the exhaust gases being sniffed by the CAT sensor. This can be optimised to reduce emissions favourably.
Unfortunately, it can’t do closed loop all the time (low revs, constant on off acceleration, broken / faulty sensor etc.) so then it goes “Open loop” and here the CAT sensor doesn’t get to play ball. During this phase only the engine fuel map is used as is.
The trouble is if the focus is only on emissions, it doesn’t make for an engine that works properly under a multitude of varying conditions.... in a car with loads of rubber mounts, slop in the suspension / drive train and four tyres and a lots of lead to dampen out the recalcitrant mess, no one really cares. But on a bike dropping it in traffic just because some moron thought they knew what they were doing is unacceptable.
More power, better control, less jaggies in the curve, all matter when you know what you are doing or just don’t want to fall off for fun.... So you need to modify the vehicle to fill in the gaps where the map (in open loop) or the CAT (in closed loop) want to starve the engine of enough fuel to run properly
As a vehicle burns petrol (...to push the piston down, which in turn spins the crank, ultimately moving the back wheel), the idea is to make the best use of the energy released. To do this well on a petrol engine, you need to get the right ratio of air to fuel.
The ratio can vary a bit depending upon conditions (temp, altitude, cruising, hard acceleration, etc.) but not by much. Any unburnt fuel produces undesirable emissions, waste resources, makes the oil dirty, washes off lube etc. To better control what's going on someone invented a sensor that's sitting in the exhaust gas flow, sniffing out what’s happening. Under the right conditions where gas flow is sufficient to get a reliable reading the vehicle goes in to a “closed loop” scenario where the fuel being injected is directly linked to the exhaust gases being sniffed by the CAT sensor. This can be optimised to reduce emissions favourably.
Unfortunately, it can’t do closed loop all the time (low revs, constant on off acceleration, broken / faulty sensor etc.) so then it goes “Open loop” and here the CAT sensor doesn’t get to play ball. During this phase only the engine fuel map is used as is.
The trouble is if the focus is only on emissions, it doesn’t make for an engine that works properly under a multitude of varying conditions.... in a car with loads of rubber mounts, slop in the suspension / drive train and four tyres and a lots of lead to dampen out the recalcitrant mess, no one really cares. But on a bike dropping it in traffic just because some moron thought they knew what they were doing is unacceptable.
More power, better control, less jaggies in the curve, all matter when you know what you are doing or just don’t want to fall off for fun.... So you need to modify the vehicle to fill in the gaps where the map (in open loop) or the CAT (in closed loop) want to starve the engine of enough fuel to run properly
