Throttle Switches - Triumph TR7 Owner's Manual

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
14
Fig. 15 Contact type throttle switch
Fig. 16 Potentiometer type throttle switch
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Throttle Switches
Throttle switches form 'part of the electronic control for the
fuel injection system and provide the E.C.U. with information
on throttle operating conditions, Two types of switches can
be used dependant upon the type of information required by
the E.C.U. to perform its function.
A
contact type
switch is fitted to TA? models and is located
on the throttle body in the engine compartment. The sWitch
contacts close when the accelerator pedal is fully depressed.
signalling to the EC.U. to lengthen the time that the main
injectors are 'open', thus supplying extra fuel for the
acceleration required.
A potentiometer type switch is fitted to TRB and Rover 3500
models on the engine plenum chamber In Ime With the
throttle input spindle, This switch is a simple electrical
potentiometer (variable resistance) whose electrical signal to
the ECU depends upon the position of the throttle spindle
and hence the accelerator pedal. The E.C.U will detect
changes in throttle position by the voltage output from the
potentiometer. Using this together With information from the
other sensors it will adjust the fuel Input accordingly. either
for degrees of acceleration and deceleration or for constant
engine speed, When a very sudden acceleration IS Signalled
to the E,C.U. by the throttle potentiometer. all Injectors are
pulsed to operate once simultaneously to ensure adequate
engine response.