INTRODUCTION
Note. Introduction information not applicable.
ES250, ES300, GS300 & LS400 (PORTED EGR VALVE)
- 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 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 operating temperature. Raise 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 below.
EGR Vacuum Modulator Check
- Turn engine off. Label and disconnect all vacuum hoses from EGR vacuum modulator. Block ports "P" and "R" with finger (twin ports on side of modulator). Blow air into port "Q" (single port on side of modulator). Air should flow freely out of filter.
- Start and run engine at 3500 RPM (ES250 and ES300) or 2500 RPM (GS300 and LS400). Block ports "P" and "R" with finger. Blow air into port "Q". Air should not flow out of filter. If air flows out of filter, replace EGR vacuum modulator.
SC300 & SC400 (PORTED EGR VALVE)
- Connect tachometer to terminal IG of check connector. Using jumper wire, jump check connector terminals TE1 and E1. Operate engine at 3500 RPM with transmission in Neutral. Remove jumper wire.
- With coolant temperature at or below 113°F (45°C), no increase in engine RPM should be noted. With coolant temperature at least 122°F (50°C), engine RPM should increase.