Chart C-7 EGR System Check - Port Fuel Injection

Chart C-7:

Chart C-7 Wiring Diagram:

CIRCUIT DESCRIPTION:

The digital EGR valve is designed to accurately supply exhaust gas to the engine without the use of manifold vacuum. The valve controls EGR flow from the exhaust to the intake manifold through three orifices, which increment in size to produce seven combinations. When the solenoid is energized, the armature, combined with an attached shaft and swivel pintle, is raised and the orifice is opened.

The flow accuracy is dependent on the orifice size only, which results in improved EGR control.


TEST DESCRIPTION:

Disconnect the four wire connector at the EGR, and then install a jumper wire, with a fuse, from the battery to terminal D of the EGR.

Start and idle the engine. At the same time, using a jumper, ground terminals A, B, and C (one at a time). You should notice a change in engine rpm as the terminal is grounded.

Terminal A should have little change on the engines rpm, but terminal C should have a large change in engine rpm (possibly stalling the engine).
Once the test sequence is completed, clear codes and verify NO "SERVICE ENGINE SOON" light exists.

NOTE:

If the digital EGR valve shows signs of excessive heat distortion, check the exhaust system for blockage (possibly a plugged converter) using the procedure in EMISSION CONTROLS/DIAGNOSING AND TESTING PROCEDURES/TESTING PROCEDURES/CATALYTIC CONVERTER.. If the exhaust system is restricted, repair the cause, one of which may a stuck open injector caused by a grounded driver circuit, defective ECM, or a stuck injector. If this condition is found, be sure and check the engine oil for fuel contamination.