Component Tests and General Diagnostics
EGR SYSTEM INSPECTION1. Inspect and clean filter in Exhaust Gas Recirculation (EGR) vacuum modulator.
(a) Remove the cap and filter.
(b) Check the filter for contamination or damage.
(c) Using compressed air, clean the filter.
(d) Reinstall the filter and cap.
NOTE: Install the filter with the coarser surface facing the atmospheric side (outward).
2. Install vacuum gauge.
Using a 3-way connector, connect a vacuum gauge to the hose between the EGR valve and Vacuum Switching Valve (VSV).
3. Inspect seating of EGR valve.
(a) Start the engine and check that the engine runs at idle.
(b) Check that the EGR valve is fully seated.
4. Connect TOYOTA hand-held tester or OBD II scan tool or equivalent. Refer to Ignition System.
5. Inspect VSV operation.
(a) The engine coolant temperature should be below 45° C (113° F).
(b) Check that the vacuum gauge indicates zero at 3,500 rpm.
(c) Warm up the engine to above 50° C (122° F).
(d) Check that the vacuum gauge indicates zero at 4,500 rpm or more.
(e) Lightly race the engine and check that the vacuum gauge indicates a vacuum and then returns to zero vacuum immediately.
6. Inspect EGR vacuum modulator operation with hot engine.
(a) Change the vacuum hose to between the EGR valve and EGR vacuum modulator.
(b) Warm up the engine to above 50° C (122° F).
(c) Check that the vacuum gauge indicates low vacuum at 3,500 rpm.
(d) Disconnect the vacuum hose port R of the EGR vacuum modulator and connect port R directly to the intake manifold with another hose.
(e) Check that the vacuum gauge indicates high vacuum at 3,500 rpm.
NOTE: As exhaust gas is increasingly recirculated, the engine will start to misfire.
7. Disconnect TOYOTA hand-held tester or OBD II scan tool or equivalent.
8. Remove vacuum gauge.
Remove the vacuum gauge, and reconnect the vacuum hoses to the proper locations.
9. Inspect EGR valve.
(a) Apply vacuum directly to the EGR valve with the engine idling.
(b) Check that the engine runs rough or dies.
(c) Reconnect the vacuum hoses to the proper locations.
NOTE: If no problem is found during this inspection, system is normal; otherwise inspect each part.