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 MANUALSMITSUBISHI1991PRECIS L4-1468CC 1.5L SOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTEMISSION CONTROL SYSTEMSEXHAUST GAS RECIRCULATIONTESTING AND INSPECTIONCALIFORNIASYSTEM OPERATIONAL TEST
1991 Mitsubishi Precis L4-1468cc 1.5L SOHC
System Operational Test
1991 Mitsubishi Precis L4-1468cc 1.5L SOHCSECTION System Operational Test
The following procedures will allow a basic operational test of the EGR system. Since the EGR operation is controlled by the ECU, refer to COMPUTERIZED ENGINE CONTROLS for further information concerning testing of the systems operation.
1. Disconnect the green striped vacuum hose from the EGR valve body and connect a hand vacuum pump using a vacuum "Tee".
2. While the engine is cold (coolant temperature less than 60 degrees C or 140 degrees F) race the engine and verify that no vacuum is present.
3. Allow the engine to warm up (coolant temperature greater than 70 degrees C or 158 degrees F) and verify that when the engine is raced vacuum rises momentarily to 14 kPa or 3.9 in. Hg.
4. Disconnect the vacuum "Tee" and connect the vacuum pump directly to the EGR valve.
5. Apply 26 kPa or 7.5in. Hg while the engine is at idle and verify that idle becomes unstable.
EGR System Inspection (California Only):
1. Disconnect the green striped vacuum hose from the EGR valve body and connect a hand vacuum pump using a vacuum "Tee".
2. While the engine is cold (coolant temperature less than 60 degrees C or 140 degrees F) race the engine and verify that no vacuum is present.
3. Allow the engine to warm up (coolant temperature greater than 70 degrees C or 158 degrees F) and verify that when the engine is raced vacuum rises momentarily to 14 kPa or 3.9 in. Hg.
EGR Valve Inspection (California Only):
4. Disconnect the vacuum "Tee" and connect the vacuum pump directly to the EGR valve.
5. Apply 26 kPa or 7.5in. Hg while the engine is at idle and verify that idle becomes unstable.
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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.