3.1L Engine
ECM operates a Electronic Vacuum Regulator Valve (EVRV) to control vacuum to the EGR valve. Regulator normally allows only a small amount of vacuum to pass to EGR valve. When ECM grounds EVRV drive circuit, EVRV opens, allowing enough vacuum to pass through to open EGR valve. ECM monitors EGR effectiveness by periodically checking fuel integrator counts. This is done when vehicle speed is greater than 50 MPH, MAP sensor signal indicates cruise condition, throttle position is constant and all conditions have been met twice for 60 seconds.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- With ignition on and engine off, EVRV should not be energized or allow enough vacuum through to open EGR valve. When test terminal "B" of the ALDL connector is grounded, EVRV will energize, allowing vacuum to the EGR valve.
- Checks for plugged EGR passages. If passages are plugged, engine may have severe detonation on acceleration.