Vacuum Modulated & Negative BACKPRESSURE EGR Valve
- Turn engine off. Disconnect vacuum hose from EGR valve. Place finger underneath valve and push up to depress valve diaphragm. With diaphragm depressed, plug vacuum port on EGR valve.
- Diaphragm should take over 20 seconds to return to its seated position. If diaphragm takes less than 20 seconds to return to its seat, replace EGR valve.
- Again depress diaphragm and plug vacuum port. Immediately start engine and watch for diaphragm movement. Diaphragm is operating properly if diaphragm moved to seated position during cranking and initial starting.
- If diaphragm did not move during cranking or initial starting, EGR valve should be cleaned.