Troubleshooting Algorithm #8 (Discovery 1)

Malfunctions	Sequence of checking nodes
The engine won't start	Grounding the engine and battery. Fuel filter, fuel pump. Tightness of the intake system and vacuum hoses. Fuses, fuel pump, engine management system relay. Engine management system connections, electrical wiring.	Coolant temperature sensor. Valve of the idling speed control system. Fuel pressure regulator and fuel pump performance. Electronic control unit (connector). "Get home" mode of operation (if used).
Difficulty starting a cold engine	Grounding the engine and battery. Engine management system connections, electrical wiring. Fuses, fuel pump, engine management system relay. Fuel filter, fuel pump. Tightness of the intake system and vacuum hoses.	Coolant temperature sensor. Valve of the idling speed control system. Fuel pressure regulator and fuel pump performance. Electronic control unit (connector). "Get home" mode of operation (if used).
Difficulty starting the engine when warm	Grounding the engine and battery. Fuses, fuel pump, engine management system relay. Fuel filter, fuel pump. Tightness of the intake system and vacuum hoses. Coolant temperature sensor. Engine management system connections, electrical wiring.	Air flow meter. Fuel pressure regulator and fuel pump performance. Injectors. Air filter. Electronic control unit (connector). Knock control (if applicable).
The engine starts and stops	Grounding the engine and battery. Fuel filter, fuel pump. Tightness of the intake system and vacuum hoses. Fuses, fuel pump, engine management system relay. Adjusting the idle speed and CO concentration in the exhaust gases.	Throttle position sensor, battery. Coolant temperature sensor. Control system connections. Electronic control unit (connector). "Get home" mode of operation (if used).
Unstable idle speed	Grounding the engine and battery. Tightness of the intake system and vacuum hoses. Valve of the idling speed control system.	Adjusting the idle speed and CO concentration in the exhaust gases. Engine management system connections, electrical wiring. Coolant temperature sensor. Knock control (if applicable). Air flow meter. Fuel pressure regulator and fuel pump performance. Electronic control unit (connector). "Get home" mode of operation (if used).
Incorrect idle speed adjustment	Tightness of the intake system and vacuum hoses. Valve of the idling speed control system.	Adjusting the idle speed and CO concentration in the exhaust gases. Coolant temperature sensor.
Misfires at idle	Grounding the engine and battery. Tightness of the intake system. Engine management system wiring. Coolant temperature sensor.	Fuel pressure and consumption. Air flow meter. Fuel pump and engine management system fuses and relays.
Misfires at constant speed	Grounding the engine and battery. Tightness of the intake system and vacuum hoses. Engine management system connections, electrical wiring.	Coolant temperature sensor. Fuel pressure regulator and fuel pump performance. Air flow meter. Fuses, fuel pump, engine management system relay.
"Dips" during acceleration	Grounding the engine and battery. Tightness of the intake system and vacuum hoses. Engine management system connections, electrical wiring. Coolant temperature sensor.	Fuel pressure regulator and fuel pump performance. Air flow meter. Electronic control unit (connector). "Get home" mode of operation (if used).
"Dips" at constant speed	Tightness of the intake system and vacuum hoses. Throttle actuator. Valve of the idling speed control system. Fuel lines.	Fuel filter, fuel pump. Injectors. Electronic control unit (connector). "Get home" mode of operation (if used).
"Dips" during engine braking	Tightness of the intake system and vacuum hoses. Engine management system connections, electrical wiring. Coolant temperature sensor.	Throttle position sensor. Fuses, fuel pump, engine management system relay. Air filter. Injectors. Air flow meter.
Detonation during acceleration	Knock control (if applicable). Engine management system connections, electrical wiring.	Air flow meter. Electronic control unit (connector).
Poor engine response to the accelerator pedal	Grounding the engine and battery. Tightness of the intake system and vacuum hoses. Engine management system connections, electrical wiring. Throttle actuator.	Coolant temperature sensor. Fuel pressure regulator and fuel pump performance. Air flow meter. Electronic control unit (connector). "Get home" mode of operation (if used).
Increased fuel consumption	Grounding the engine and battery. Adjusting the idle speed and CO concentration in the exhaust gases. Throttle position sensor. Throttle valve, throttle body, sticking, initial position.	Engine management system connections, electrical wiring. Coolant temperature sensor. Air flow meter. Electronic control unit (connector). The operating mode is "get home".
The CO concentration in the exhaust gases is too high	The operating mode is "get home". Electronic control unit, connector. Emission control system and exhaust gas recirculation valve (if installed). Engine management system connections, electrical wiring.	Tightness of the intake system and vacuum hoses. Coolant temperature sensor. Fuel pressure / pump capacity / pressure regulator.
The CO concentration in the exhaust gases is too low	Grounding the engine and battery. Tightness of the intake system and vacuum hoses. Adjusting the idle speed and CO concentration in the exhaust gases. Coolant temperature sensor.	Engine management system connections, electrical wiring. Injectors. Electronic control unit (connector). "Get home" mode of operation (if used). Air flow meter. Fuel pressure regulator and fuel pump performance.
Loss of power	Grounding the engine and battery. Tightness of the intake system and vacuum hoses. Throttle actuator. Engine management system connections, electrical wiring.	Coolant temperature sensor. Fuel pressure regulator and fuel pump performance. Air flow meter. Electronic control unit (connector). "Get home" mode of operation (if used).