Volvo Workshop Manuals
940 L4-2.3L SOHC VIN 88 B230F (1992)
Relays and Modules > Relays and Modules - Powertrain Management > Relays and Modules - Computers and Control Systems > Engine Control Module > Component Information > Description and Operation > Fuel Injection > Page 921
^ "CHECK ENGINE" light.
The cold engine start-up program provides for two injection periods per revolution. When the engine has reached operating temperature, the ECU
The cold start injector is activated when the temperature is below -15°C (5°F) or below and the engine is below 900 RPM. Above 900 RPM the
This program provides a richer air/fuel mixture until the engine coolant has reached a temperature of 60°C (140°F) or above.
NORMAL DRIVING PROGRAM:
During normal driving, the ECU uses various input devices (mostly the mass air flow sensor signal) to regulate injection frequency.
FULL LOAD AND ACCELERATION PROGRAM:
During full load or acceleration, a richer air/fuel mixture is provided to achieve maximum engine power. This will also keep combustion heat and
During deceleration, the fuel injectors are turned off (in all gears) if engine speed is above 2,000 RPM. Injection is resumed between 1,400 and
Knock causes high and dangerous combustion temperatures. Therefore the fuel injection system provides a richer air/fuel mixture to counteract
RPM LIMITER PROGRAM:
At excess RPM the fuel injectors are turned off to keep the engine from overrevving.
SELF ADJUSTING FUNCTION:
The ECU is adaptive to your driving style or environment. It will adjust its calculations according to assimilated input. Whenever the vehicle is
SELF ADJUSTING IDLE SPEED FUNCTION:
In time, normal use, wear and coatings will affect the operation of the throttle valve causing less air to enter the intake system. The ECU will
SELF ADJUSTING LAMBDA SOND FUNCTION:
The lambda sond (oxygen sensor) operates in a similar fashion. It senses if the air/fuel mixture is rich or lean and the ECU adjusts the fuel injector
This self-regulating function keeps the air/fuel mixture at a constant midpoint. Therefore the need to adjust CO content is eliminated and is not
There is a "limp home" mode provided when the signal from the mass air flow sensor ceases for some reason (hot wire defect, wiring....). This
If the self diagnostic circuit ("on board diagnostics") in the ECU detects a fault in the fuel injection system, it will activate the "CHECK ENGINE"
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