1990-93 ES250, ES300, GS300 & LS400 (Ported EGR Valve)
WARNING: This page does not describe the selected car, but rather 49 other vehicles, including the 2014 Lexus RX 450h, 2014 Lexus GX 460, 2014 Lexus ES 300h, 2014 Lexus CT 200h, and 2013 Lexus RX 450h. However, it is still accessible from the selected car via links, so may be relevant.
- Using a vacuum "T", connect a vacuum gauge between EGR vacuum hose and EGR valve (between EGR vacuum hose and vacuum switching valve on LS400). To ensure EGR valve is seating, start engine and check idle quality. If EGR valve is not seating, replace EGR valve.
- With coolant temperature at less than 104°F (40°C) on ES250, 95°F (35°C) on ES300, 122°F (50°C) on GS300, or 127°F (53°C) on LS400, vacuum gauge should indicate zero vacuum at 2500 RPM. Warm engine to normal operating temperature. Increase engine speed to 2500 RPM. Vacuum gauge should indicate low vacuum. If vacuum gauge does not indicate low vacuum, go to next step.
- Disconnect vacuum hose from port "R" of EGR vacuum modulator (lower of 2 ports on side of modulator). Connect port "R" directly to intake manifold using another vacuum hose. Vacuum gauge should indicate high vacuum with engine at 3500 RPM (ES250 and ES300), or 2500 RPM (GS300 and LS400).
- Engine may misfire slightly. Let engine idle. Remove vacuum gauge, and reconnect all vacuum hoses. Disconnect vacuum hose from EGR valve. Apply vacuum directly to EGR valve. Engine should run rough or stall. If results are as indicated, system is okay. If results are not as indicated, see EGR VACUUM MODULATOR CHECK.