Civic Si: Drive-by-Wire Throttle Control
An electronic drive-by-wire system helps enhance the driving character of the Civic Si. With smart electronics connecting the throttle pedal to the throttle butterfly valve in the intake manifold, the engine response can be optimized to suit the driving conditions and to better match the driver's expectations. By eliminating the direct throttle cable connection to the engine, the ratio between pedal movement and throttle butterfly movement can be continuously optimized. The Civic Si uses a DC motor to control the throttle butterfly position in the intake tract. To establish the current driving conditions, the system monitors pedal position, throttle position, vehicle speed, engine speed and engine vacuum. This information is then used to define the throttle control sensitivity.

Civic Si: Programmed Fuel Injection (PGM-FI)
The Civic Si is equipped with a Programmed Fuel Injection (PGM-FI) system. The system monitors throttle position, engine temperature, intake-manifold pressure, atmospheric pressure, exhaust-gas oxygen content, and intake-air temperature. It controls fuel delivery by multi-holed injectors mounted in the cast-aluminum intake manifold. The ECU also tracks the operation of the engine with position sensors on the crankshaft and both camshafts.

Civic Si: Direct Ignition System
To ensure a hot, stable spark at high rpm operation, a coil mounted atop each spark plug, helps ensure a stable spark up to 8000 rpm. A sensor mounted behind one of the camshafts is the trigger for spark plug ignition. Also, specially designed iridium-tipped spark plugs help increase ignition energy and enhance plug life.

Civic Si: Exhaust System
A stainless steel, low heat-mass exhaust system is standard on the Civic Si. The system employs a high-density catalytic converter for improved light-off performance and reduced hydrocarbons and NOx. Emissions performance is further improved thanks to the engine's design, which positions the exhaust manifold on the rear of the engine-which shortens the distance that the exhaust gases must travel to the catalytic converter, resulting in faster light-off and more complete conversion of the exhaust gases. The exhaust system also incorporates an "e-shaped" dual-path pipe that optimizes the exhaust flow for improved torque and lower emissions. By employing a large diameter tail pipe (60.5 mm), an exhaust flow of 105 liters per second is achieved.

Civic Si: Noise, Vibration and Harshness (NVH) Control
In addition to its outstanding power and response, the Civic Si engine has been engineered for class-leading smoothness and refinement. The 2.0-liter four-cylinder employs such NVH-reducing features as a chain-driven balancer unit in the oil pan; a highly rigid, ferrous-carbon inserts in the main bearing caps for added rigidity; a one-piece crankshaft carrier; a silent chain cam drive; and a stiff, cast-aluminum oil pan. A torque rod damper system added to the subframe helps reduce rocking and isolate powertrain NVH from the passenger compartment. The torque rod engine mount system consists of an upper torque rod attached to the transmission and a lower torque rod attached to the engine, a hydraulic body mount and a front beam stopper. The torque rod damper system is also used on all other Civic models, but without the front beam stopper.

Civic Si: Maintenance Minder System and Tune-Up Intervals
The Civic Si's engine tune-up schedule is calculated by the Maintenance Minder system. The Maintenance Minder system automatically indicates when to have standard service performed based on actual driving conditions (tracked by the ECU) and minimizes the guesswork related to whether the vehicle is being used in standard or severe use conditions for maintenance interval purposes. The display indicates when to change the oil, air cleaner, transmission fluid, spark plugs or coolant, as well as when to rotate the tires.

A tune-up is not required until 100,000 miles or more (only routine inspections and fluid changes are required up to this point). Credit for this longevity goes to long-wearing platinum-tipped spark plugs, a long-life timing chain, and careful engineering of the precisely manufactured DOHC valvetrain-which reliably maintains proper valve tappet clearances until the first tune-up.

Source: Honda PR