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.
2008 Mitsubishi Eclipse L4-2.4L (4G69)FACTORY OEM SERVICE PROCEDURE
Exhaust Gas Recirculation: Description and Operation
EXHAUST GAS RECIRCULATION (EGR) SYSTEM
GENERAL DESCRIPTION (EXHAUST GAS RECIRCULATION SYSTEM)
The exhaust gas recirculation system (EGR) lowers the nitrogen oxides (NOx) emission level. When the air/fuel mixture combustion temperature is high, a large quantity of NOx is generated in the combustion chamber. Therefore this system recirculates part of exhaust gas from the exhaust port of the cylinder head to the combustion chamber through the intake manifold to decrease the air/fuel mixture combustion temperature, resulting in reduction of NOx. The EGR flow rate is controlled by the EGR valve (Stepper Motor) for driveability quality.
OPERATION
When the engine coolant temperature is low, when the engine is at idle or when a wide open throttle operation is performed the EGR valve (Stepper Motor) is kept closed achieving no EGR. After warming up the engine the EGR valve (Stepper Motor) can be opened by the engine control module (ECM) or powertrain control module (PCM).
The ECM or PCM monitors the EGR system and illuminates the Malfunction Indicator Lamp (SERVICE ENGINE SOON or Check Engine Lamp) to indicate that there is a malfunction.
SYSTEM DIAGRAM
GENERAL DESCRIPTION (EXHAUST GAS RECIRCULATION SYSTEM)
The exhaust gas recirculation system (EGR) lowers the nitrogen oxides (NOx) emission level. When the air/fuel mixture combustion temperature is high, a large quantity of NOx is generated in the combustion chamber. Therefore this system recirculates part of exhaust gas from the exhaust port of the cylinder head to the combustion chamber through the intake manifold to decrease the air/fuel mixture combustion temperature, resulting in reduction of NOx. The EGR flow rate is controlled by the EGR valve (Stepper Motor) for driveability quality.
OPERATION
When the engine coolant temperature is low, when the engine is at idle or when a wide open throttle operation is performed the EGR valve (Stepper Motor) is kept closed achieving no EGR. After warming up the engine the EGR valve (Stepper Motor) can be opened by the engine control module (ECM) or powertrain control module (PCM).
The ECM or PCM monitors the EGR system and illuminates the Malfunction Indicator Lamp (SERVICE ENGINE SOON or Check Engine Lamp) to indicate that there is a malfunction.
SYSTEM DIAGRAM
System Diagram:
Factory Service Tools
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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.
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