When the lambda sensor reports the mixture is rich, the ECU injects less fuel. This way the ECU is able to adjust the air/fuel ratio based on the actual result of the combustion. In closed loop mode, the ECU will use the input from the lambda sensor in the exhaust to determine the correct amount of fuel to inject to the engine. When you operate the motorcycle at a constant speed (constant load, constant throttle), the ECU switches to closed-loop mode.
The point of closed-loop is to get as close as possible to an efficient air/fuel mixture. In motorcycles (and cars), the “measuring element” is usually an oxygen sensor.īelow I’ll explain this in more detail, including when a motorcycle is in closed loop vs open loop, and how it affects the way you ride. That diagram is a simplified representation of how closed and open loop systems work. See this diagram: Open vs Closed Loop system In closed loop mode, the engine listens to the lambda sensor to adjust fuel/air mixture. The sensor in question is a lambda sensor, also known as an oxygen sensor or air/fuel ratio mixture sensor. In open loop mode, the engine doesn’t listen to nobody, it just runs off a set of instructions based on where the throttle is at, where the revs are, and so on.
In a nutshell, closed loop is where the engine operates with a feedback loop. Fuel-injected engines - basically, most motorcycles since the mid-2000s (and almost all that I buy) that have sensors and fuel controllers. Sign up Open Loop vs Closed Loop in a nutshellĬlosed and open-loop conditions apply only to fuel-injected engines.