Exhaust Gas RECIRCULATION System Check

Disconnect the vacuum hose (black) from the exhaust gas recirculation (EGR) valve, and then connect a hand vacuum pump via the Tee-fitting.

Fig 1: Connecting Hand Vacuum Pump Via Tee-Fitting (2.4L Engine)
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

Fig 2: Connecting Hand Vacuum Pump Via Tee-Fitting (3.0L Engine)
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

Start the engine. As described in the chart below, check the vacuum condition when the throttle valve is opened suddenly (revving) during cold and hot engine conditions.

When engine is cold

[Engine coolant temperature: 20°C (68°F) or less]

THROTTLE VALVE VACUUM CONDITION CHART

THROTTLE VALVE	NORMAL VACUUM CONDITION
Open quickly	No vacuum (Remained as barometric pressure).

When engine is hot

[Engine coolant temperature: 80°C (176°F) or more]

THROTTLE VALVE VACUUM CONDITION CHART

THROTTLE VALVE	NORMAL VACUUM CONDITION
Open quickly	Momentarily rises over 13 kPa (3.9 in Hg)

Stop the engine. Remove the Tee-fitting and the hand vacuum pump.
Connect the hand vacuum pump directly to the EGR valve.

Fig 3: Connecting Hand Vacuum Pump Directly To EGR Valve (2.4L Engine)
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

Fig 4: Connecting Hand Vacuum Pump Directly To EGR Valve (3.0L Engine)
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Start the engine and run at idle until warm.
The engine idling speed should be rough when a vacuum of 29 kPa (8.7 in Hg) or more is applied to the EGR valve.
If engine idles rough, EGR passage is open and the system is OK. If engine idle is not rough, the EGR passage and the valve must be checked for restrictions. Perform the EGR valve check. Then repeat the exhaust gas recirculation system check.