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 MANUALSPLYMOUTH1985CONQUEST L4-2555CC 2.6L SOHC TURBOREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTEMISSION CONTROL SYSTEMSEXHAUST GAS RECIRCULATIONTESTING AND INSPECTIONEGR FUNCTIONAL TESTS
1985 Plymouth Conquest L4-2555cc 2.6L SOHC Turbo
EGR Functional Tests
1985 Plymouth Conquest L4-2555cc 2.6L SOHC TurboSECTION EGR Functional Tests
1. Start engine and operate at idle speed.
2. With coolant temperature below 131°F, increase engine speed to 2500 RPM and check to ensure that secondary EGR valve is not operating. If secondary EGR valve is operating, replace thermo valve.
3. Allow coolant temperature to exceed 133°F, then increase engine speed to 2500 RPM and check secondary EGR valve operation. If secondary EGR valve does not operate, check EGR control valve and thermal valve and replace as necessary.
4. Disconnect green stripe hose at carburetor and connect a vacuum pump to vacuum hose.
5. While operating sub-EGR valve by hand, apply 5.9 inches Hg of vacuum with vacuum pump.
6. If idle speed becomes unstable, the secondary EGR valve is operating properly. If idle speed remains unchanged, replace EGR valve.
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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.