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 MANUALSPLYMOUTH1993LASER FWD L4-1753CC 1.8L SOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTEMISSION CONTROL SYSTEMSEXHAUST GAS RECIRCULATIONTESTING AND INSPECTIONSYSTEM OPERATIONAL TEST
1993 Plymouth Laser FWD L4-1753cc 1.8L SOHC
System Operational Test
1993 Plymouth Laser FWD L4-1753cc 1.8L SOHCSECTION System Operational Test
Note: 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 and connect a hand vacuum pump through a vacuum "Tee".
2. While the engine is cold (coolant temperature less than 20 degrees C or 68 degrees F) race the engine and verify that vacuum is not present.
3. Allow the engine to warm up (coolant temperature greater than 70 degrees C or 158 degrees F).
4. Race the engine and verify that vacuum increases to 100 mm Hg or 3.9 in. Hg or more.
5. Disconnect the vacuum "Tee" and connect the vacuum pump directly to the EGR valve.
6. Using the vacuum pump apply 215 mm Hg or 8.5 in. Hg of vacuum while the engine is at idle and verify that idle becomes unstable.
EGR Vacuum Delivery Test:
1. Disconnect the green striped vacuum hose from the EGR valve and connect a hand vacuum pump through a vacuum "Tee".
2. While the engine is cold (coolant temperature less than 20 degrees C or 68 degrees F) race the engine and verify that vacuum is not present.
3. Allow the engine to warm up (coolant temperature greater than 70 degrees C or 158 degrees F).
4. Race the engine and verify that vacuum increases to 100 mm Hg or 3.9 in. Hg or more.
EGR Valve Inspection:
5. Disconnect the vacuum "Tee" and connect the vacuum pump directly to the EGR valve.
6. Using the vacuum pump apply 215 mm Hg or 8.5 in. Hg of vacuum 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.