Intelligent Engine Management
It's remarkably clever: STIHL presents the world's first chain saw models with intelligent engine management . An innovative regulating system controls the full-load mix and top speed of the machines electronically. That way, the chain saw always delivers optimum engine power as well as offering even greater convenience and environmental friendliness. STIHL sets new standards with this pioneering chain saw design concept. STIHL chain saws with intelligent engine management are indicated by the letter "I" in the model name.
- Optimum engine performance at all times: An innovative regulating system automatically controls the full-load mix and top speed of the machine.
- Good lugging power: The machines always reach a constant maximum speed and are characterised by their outstandingly good acceleration.
- The correct carburetor setting, automatically: No need for manual adjustments in changing temperatures or when working under different conditions, such as at high altitude or with a dirty air filter.
- Efficient and environmentally friendly: Because the fuel-air mix always remains within the optimum range, the engine uses less fuel and produces lower exhaust emissions.
This is how it works
The regulating cycle starts if the chain saw is operated for 5 seconds under constant full throttle. The solenoid valve closes for a fraction of a second. The resulting speed change is electronically measured and analysed. According to the result the fuel-air mix is readjusted to keep it always within the optimum range. In full-throttle mode the mix ratio is automatically regulated every 5 seconds.
Solenoid valve in the carburetor
The digitally controlled solenoid valve opens and closes 30 times per second. That way, the fuel supply is precision-controlled.
Microprocessor in the ignition module
The microprocessor monitors the engine speed and controls the solenoid valve.
A second pair of poles on the flywheel provides the necessary power supply for the microprocessor and the solenoid valve.
Constant top speed
Intelligent engine management is active even during uncontrolled rich come-down at full throttle. If the engine speed exceeds the upper limit of 14,000 rpm the mix is enriched to bring the speed back down to 14,000 rpm. This ensures a constant maximum speed.