Catalytic Converter; Idle Speed Control Motor; Servomotor For The 2Nd Throttle Valve - KTM 2003 950 Adventure Repair Manual

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Catalytic converter

The catalytic converter is installed in the main silencer and transforms
most of the main toxic constituents into non-toxic compounds. It is
designed as a three-way catalytic converter and consists of a coiled
metal support whose surface is coated with precious metals such as
platinum and rhodium; the coating only weighs 1 to 2 grams.
Similar to the lambda probe, the catalytic converter is not activated
until a temperature of approx. 300º C is reached; it operates best
between 400º C and 800º C. Thermal aging accelerates at a
temperature of 800º C. Much higher temperatures occur if the
ignition/injection system (e.g.: ignition faults) malfunctions, which can
destroy the catalytic converter.
The main constituents in the emissions are nitrogen (N2, not involved
in combustion), carbon dioxide (CO2, the result of complete
combustion) and water or steam (H2O, is bound in the fuel and
released during combustion); together they comprise approx. 90% of
emitted exhaust gas and are considered harmless.
The rest mainly consists of carbon monoxide and hydrocarbon (CO and
HC, both the result of incomplete combustion) and nitrogen oxide
(NOx, the result of high combustion chamber temperature); all three
are toxic.
To effectively convert these 3 components into harmless carbon
dioxide, water and nitrogen in the catalytic converter, the engine must
be operated close to lambda 1, i.e. the efficiency of combustion is
greatest close to lambda 1.
But lambda 1 is almost impossible to achieve by control engineering,
which is why the control unit continuously (several times each second)
produces mixtures alternating between lambda 0.97 (rich mixture) and
1.03 (lean mixture). Under these conditions the voltage generated by
the lambda probe varies between 0.2 volt and 0.8 volt depending on
the exhaust gas composition.

Idle speed control motor

The idle speed control motor is mounted to the throttle valve body;
1
it is a stepper motor driven by the control unit to achieve a calculated
speed setting.
1

Servomotor for the 2nd throttle valve

The function, construction and installed position are the same as for
the idle speed control motor; however, the stepper motor for the 2nd
throttle valve controls the position of the 2nd throttle valve.
2
2