1993 Jeep Cherokee

1990-95 ENGINE PERFORMANCE Jeep EGR Function Testing

All Models

EGR VALVE

PORTED EGR SYSTEM

1. Check vacuum hoses for correct routing. Warm engine to
   normal operating temperature. Set engine speed to fast idle (or high
   enough to obtain 5 in Hg at EGR valve). Protect finger from heat and
   place finger beneath EGR valve so diaphragm movement can be felt.

2. Disconnect vacuum hose from EGR valve. Diaphragm should
   move downward (valve closed) and increase in engine RPM should be
   noticed. Reconnect vacuum hose to EGR valve. Diaphragm should move
   upward (valve open) and engine speed should decrease by at least 150
   RPM.

3. If EGR diaphragm does not move during the test, check for
   vacuum at hose. If vacuum is present, replace EGR valve. If vacuum is
   not present, check for leaking vacuum hose or plugged carburetor port.
   If EGR diaphragm moves during the test, but RPM does not change, check
   for plugged EGR port or passages.