Skylark L4-144 2.4L DOHC VIN T SFI (1997)
EGR Valve: Description and Operation
DESCRIPTION
A linear EGR valve is used on this system. The linear EGR valve is designed to accurately supply exhaust gases to the engine without the use of
intake manifold vacuum. The valve controls exhaust flow going into the intake manifold from the exhaust manifold through an orifice with a PCM
controlled pintle. The PCM controls the pintle position using inputs from the Throttle Position (TP) and Manifold Absolute Pressure (MAP)
sensors. The PCM then commands the EGR valve to operate when necessary by controlling a ground signal through the PCM. This can be
monitored on a scan tool as the Desires EGR Position.
LINEAR EGR CONTROL
The PCM monitors the results of its command through a feedback signal. By sending a 5 volt reference and a ground to the EGR valve, a voltage
signal representing the EGR valve pintle position is sent to the PCM. This feedback signal can also be monitored on a scan tool and is the actual
position of the EGR pintle. The actual EGR position should always be near the commanded or the desired EGR position.