Egr Valve Closing Test - Jeep 1987 Wrangler Workshop Manual

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#P1
ENGINES
#P1
EXHAUST GAS RECIRCULATION SYSTEM
A distinct movement should be noticed in the
E G R valve control diaphragm (1).
S E E
I.S.
N
O
T
E
S
1. Control Diaphragm
2. Power Diaphragm
3. Vent Valve
4. Vacuum Hose Nipple
5. Pintle
6. Control Flow Area
840237
If the diaphragm does not move, the probable
causes are a:
• defective vacuum hose to the E G R valve
• defective E G R valve diaphragm
• defective back-pressure sensor diaphragm.
Inspect the vacuum hoses for air leaks.
EGR Valve Closing Test
WARNING: Use extreme caution when the
engine is operating. Do not stand in a direct line
with the fan. Do not put your hands near the
pulleys, belts or fan. Do not wear loose clothing.
With the engine at normal operating temper-
ature and at curb idle speed, manually depress
the E G R valve diaphragm.
This should cause an immediate drop in engine
RPM and indicate that the E G R valve has been
properly preventing the flow of exhaust gas to
the intake manifold at idle speed.
If there is no change in engine RPM and the
engine is idling properly, exhaust gases are not
reaching the combustion chamber.
The probable malfunction is a restricted
passage between the E G R valve and the intake
manifold.
If the engine idles improperly and RPM is not
greatly affected by depressing the E G R valve
diaphragm, the E G R valve is not preventing the
flow of exhaust gases to the intake manifold.
There is either a fault in the vacuum hoses,
improper hose connection or the valve is
defective.
B-238

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