Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSSUBARU2007FORESTER F4-2.5L SOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMDESCRIPTION AND OPERATIONIGNITION CONTROL
2007 Subaru Forester F4-2.5L SOHC
Ignition Control
2007 Subaru Forester F4-2.5L SOHCSECTION Ignition Control
IGNITION CONTROL
- The ECM determines operating condition of the engine based on signals from the manifold absolute pressure sensor, engine coolant temperature sensor, intake air temperature sensor, crankshaft position sensor and other sources. The ECM then selects the ignition timing most appropriate for the condition thus determined from those stored in its memory and outputs at that timing a primary current OFF signal to the igniter to initiate ignition.
- This control uses a quick-to-response learning feature by which the data stored in the ECM memory is processed in comparison with information from various sensors and switches.
- Thus, the ECM can always perform optimum ignition timing taking into account the output, fuel efficiency, exhaust gas, and other factors for every engine operating condition.
- Ignition control during start-up Engine speed fluctuates during start of the engine, so the ECM cannot control the ignition timing. During that period, the ignition timing is fixed at 10 ° BTDC by using the 10 ° signal from the crankshaft position sensor.
- Ignition control after start of engine
From the time to receive crank angle signals indicating 1800 of a turn, the ECM measures the engine speed, and by using this data it decides the dwell set timing and ignition timing according to the engine condition.
- The ECM determines operating condition of the engine based on signals from the manifold absolute pressure sensor, engine coolant temperature sensor, intake air temperature sensor, crankshaft position sensor and other sources. The ECM then selects the ignition timing most appropriate for the condition thus determined from those stored in its memory and outputs at that timing a primary current OFF signal to the igniter to initiate ignition.
- This control uses a quick-to-response learning feature by which the data stored in the ECM memory is processed in comparison with information from various sensors and switches.
- Thus, the ECM can always perform optimum ignition timing taking into account the output, fuel efficiency, exhaust gas, and other factors for every engine operating condition.
- Ignition control during start-up Engine speed fluctuates during start of the engine, so the ECM cannot control the ignition timing. During that period, the ignition timing is fixed at 10 ° BTDC by using the 10 ° signal from the crankshaft position sensor.
- Ignition control after start of engine
From the time to receive crank angle signals indicating 1800 of a turn, the ECM measures the engine speed, and by using this data it decides the dwell set timing and ignition timing according to the engine condition.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.