Saab 9000 - Fuel Injection

Fuel injection
Fuel injection in the Saab Trionic system is sequen-
tial, which means that injection follows the engine's
firing order. ·
Injection duration is calculated by the engine control
module mainly on the basis of the following informa-
tion:
• pressure in the intake manifold
• intake air temperature
• engine speed
• engine coolant temperature
• oxygen content of the exhaust gases
• knocking, if any
• throttle position
Technical Description 21
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Pre-injection
As soon as the engine starts to rotate and the elec-
tronic control module receives pulses from the crank-
shaft position sensor, the main relay and fuel pump
relay operate, causing all injectors to open simulta-
neously and squirt a small amount of fuel into the in-
take valves. Injector opening duration is determined
by the coolant temperature.
The purpose is to achieve short starting times. After
this initial injection of fuel, the system reverts to regu-
lar sequential multipoint fuel injection.
Saab 9000
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