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 MANUALSHYUNDAI1991SONATA V6-3.0LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTEMISSION CONTROL SYSTEMSEXHAUST GAS RECIRCULATIONTESTING AND INSPECTIONFEDERALSYSTEM TEST
1991 Hyundai Sonata V6-3.0L
System Test
1991 Hyundai Sonata V6-3.0LSECTION System Test
Testing The EGR System:
1. Disconnect the vacuum hose (green stripe) from the throttle body and connect a manual vacuum pump to the vacuum hose.
2. While the engine is cold (coolant temperature less than 50 degrees C or 122 degrees F) verify that while the engine is idling, vacuum leaks from the thermo valve.
3. Allow the engine to warm up (coolant temperature greater than 85 degrees C or 185 degrees F) and verify that while the engine is idling 6 kPa (2 in. Hg) of vacuum can be applied and held without affecting engine idle.
4. Apply 23 kPa (7 in. Hg) of vacuum and verify that engine idle becomes slightly unstable.
RENDER: 1.0x
NO RELATED
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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.