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 SYSTEMSEVAPORATIVE EMISSIONS SYSTEMTESTING AND INSPECTIONSYSTEM TEST
1991 Hyundai Sonata V6-3.0L
System Test
1991 Hyundai Sonata V6-3.0LSECTION System Test
Fig. 57 Testing the purge control valve:
SYSTEM TESTING
1. Disconnect the vacuum hose (red stripe) from the throttle body and connect a manual vacuum pump to the hose.
2. While the engine is cold (coolant temperature less than 60 degrees C or 140 degrees F) verify that when 53 kPa (15 in. Hg) of vacuum is applied while holding the engine at 2,500 rpm that vacuum can be held.
3. Allow the engine to warm up (coolant temperature greater than 70 degrees C or 158 degrees F) and verify that while the engine is idling and the air conditioner switch is on that vacuum leaks.
4. Turn the air conditioning switch off and verify that while the engine continues to idle it is possible to produce 53 kPa (15 in. Hg) of vacuum.
5. Open the throttle until the engine is running at 2,500 rpm and verify that for three minutes vacuum leaks but after three minutes of operation vacuum holds for a short period and then leaks once again.
RENDER: 1.0x
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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.