Exhaust Gas Recirculation: Testing and Inspection

The EGR system is used to reduce oxides of nitrogen entering the atmosphere by recirculating exhaust gases through the EGR valve and intake manifold and into the combustion chambers. The system is comprised of an EGR valve, a CVC valve, an EGR control solenoid valve, the ECU, and various sensors.
The ECU contains memories for ideal EGR valve lift for various engine operating conditions. The valve lift sensor detects the amount of EGR valve lift and relays this information to the ECU. The ECU then compares this information with the ideal lift determined by signals sent from various sensors. If a significant difference exists between the two, the ECU stops current to the solenoid valve, thereby reducing vacuum applied to the EGR valve.

Testing

If the EGR system malfunctions, a failure code will be set in the ECU memory and the PGM-FI warning light on the dash will illuminate. To diagnose the malfunction, refer to ``PGM-FI SYSTEM SELF-DIAGNOSIS'' (failure code 12) as outlined in ``Fuel Injection.''