EGR Valve
- With engine idling, disconnect EGR vacuum hose. Apply vacuum directly to EGR valve. Engine should run rough or stall and EGR should hold vacuum. If engine RPM was not affected, go to step 2). If EGR valve does not hold vacuum, replace EGR valve.
- Manually compress EGR valve diaphragm from underside. If engine RPM does not change, remove EGR valve and inspect EGR passages for blockage. If engine RPM is affected by lifting EGR valve diaphragm, replace EGR valve.