1978 Rabbit & Scirocco
- Start and warm engine to normal operating temperature. Disconnect vacuum hose to EGR valve and temporarily connect vacuum hose from power brake booster to EGR valve. Engine should run rough or stall. If engine does not respond as indicated, check for plugged EGR passage or faulty EGR valve.
- Connect vacuum gauge to temperature valve, in place of vacuum hose that goes to EGR valve. With engine at normal operating temperature, there should be 2-4 in Hg. If vacuum reading is not as specified, replace temperature valve.