GM Cutlass RWD 1970-1987 Repair Guide

Exhaust Gas Recirculation (EGR)


To lower the formation of Oxides Of Nitrogen (NOx) it is necessary to reduce combustion temperatures. This is done by introducing exhaust gases into the cylinders.


Vacuum Regulator Valve (VRV)

The Vacuum Regulator Valve is attached to the side of the injection pump and regulates vacuum in proportion to throttle angle. Vacuum from the vacuum pump is supplied to port A and vacuum at port B is reduced as the throttle is opened. At closed throttle, the vacuum is 15 in. Hg (103 kPa), at half throttle 6 in. Hg (41 kPa), at wide open throttle there is zero vacuum.

Exhaust Gas Recirculation (EGR) Valve V8

Apply vacuum to vacuum port. The valve should be fully open at 10.5 in. Hg (72 kPa) and closed below 6 in. Hg (41 kPa)

Exhaust Gas Recirculation (EGR) Valve V6

Apply vacuum to vacuum port. The valve should be fully open at 12 in Hg (82 kPa) and closed below 6 in (41 kPa).

Response Vacuum Reducer (RVR)

Connect a vacuum gauge to the port marked To EGR valve or TCC solenoid. Connect a hand operated vacuum pump to the VRV port. Draw a 15 in. Hg (50.66 kPa) vacuum on the pump and the reading on the vacuum gauge should be lower than the vacuum pump reading as follows:

  1. 75 in. HG. (517 kPa) Except High Altitude V8
  3. High Altitude V8

Torque Converter Clutch Operated Solenoid

When the torque converter clutch is engaged, an electrical signal energizes the solenoid allowing ports 1 and 2 to be interconnected. When the solenoid is not energized, port 1 is closed and ports 2 and 3 are interconnected.

  1. Ports 1 and 3 are connected

  1. Ports 2 and 3 are connected.

Vacuum Modulator Valve (VMV) V6

To test the VMV, block the drive wheels, apply the parking brake, with the shift lever in Park, start the engine and run at slow idle. Connect a vacuum gauge to the hose that connects to the port marked MAN. There should be at least 14 in. Hg (97 kPa) of vacuum. If not, check the vacuum pump, VRV, RVR, solenoid and connecting hoses. Reconnect the hose to the "Man" port. Connect a vacuum gauge to the "DIST" port on VMV. The vacuum reading should be as follows:

  1. 12 in. Hg (83 kPa) Except High Altitude
  3. 9 in. Hg (62 kPa) High Altitude