DR-18A EGR Vacuum From Throttle Body to EGR BP-Valve

1. Disconnect throttle body to EGR back pressure valve vacuum line at the valve.
2. Connect a vacuum gauge to the disconnected line, then start the engine and raise engine speed to 2,000 RPM.
3. If vacuum gauge indicates at least 5 inches of vacuum, note reading and proceed to step B. DR-18B Vacuum Supply From Back Pressure Valve to EGR
4. If vacuum gauge indicates vacuum is below 5 inches, repair vacuum supply.