All Vehicles Without A.I.R. or Pulsair

1. With engine at normal operating temperature, connect a vacuum gage to any convenient vacuum port on intake manifold.

2. Disconnect EGR solenoid electrical connector or connect EGR valve directly to vacuum source bypassing any switches or solenoids.

3. Run engine at 1000 RPM and record vacuum reading.

4. Increase RPM slowly to 2500 RPM. Note vacuum reading at steady 2500 RPM.

5. If vacuum at 2500 RPM decreases more than 3" from the reading at 1000 RPM, the exhaust system should be inspected for restrictions.

6. Disconnect exhaust pipe from engine and repeat steps 3 & 4. If vacuum still drops more than 3" with exhaust disconnected, check valve timing.