Checking The Egr System - DaimlerChrysler Jeep Grand Cherokee 2002 Service Manual

DRIVEABILITY - DIESEL
Symptom:

*CHECKING THE EGR SYSTEM

EGR VALVE
CHECKING VACUUM SUPPLY
EGR SOLENOID
TEST
1 Turn the ignition off.
Disconnect both vacuum lines at the EGR Solenoid.
Using a vacuum line connection tee, connect the vacuum supply line to the EGR
Solenoid Output line at the EGR Solenoid.
Disconnect the vacuum line at the EGR Valve.
Connect a vacuum gauge to the EGR Solenoid Output line at the EGR Valve.
Start the engine.
With the engine at idle, note the vacuum gauge reading.
Is the vacuum above 22 inches?
Yes → Go To 2
→ Inspect the vacuum hoses/tubes for damage, restriction and leaks.
No
2 NOTE: The engine must be at operating temperature for this test to be valid.
Turn the ignition off.
Disconnect the vacuum line at the EGR Valve.
Connect a vacuum gauge to the EGR Solenoid Output line at the EGR Valve
Start the engine and observe the vacuum gauge reading for 1 minute.
NOTE: The vacuum reading should increase to above 18 inches approxi-
mately 5 seconds after the engine is started. The vacuum should decrease to
below 4 inches within 40 seconds of engine run time.
Did the vacuum reading increase to above 18 inches then decrease below 4 inches as
described?
Yes → Go To 3
→ Replace the EGR Solenoid.
No
3 Turn the ignition off.
Disconnect both vacuum lines at the EGR Solenoid.
Using a vacuum line connection tee, connect the vacuum supply line to the EGR
Solenoid Output line at the EGR Solenoid.
Test drive the vehicle and note the vehicles performance.
NOTE: With the connection tee in place the EGR valve will receive full
vacuum supply with the engine running. This should cause a severe
reduction in engine power.
Does the vehicle exhibit a severe loss of power?
Yes → Test Complete.
→ Replace the EGR Valve.
No
POSSIBLE CAUSES
ACTION
If o.k. refer to the Service Information to check the Vacuum Pump
operation.
Perform ROAD TEST VERIFICATION - VER-2.
Perform ROAD TEST VERIFICATION - VER-2.
Perform ROAD TEST VERIFICATION - VER-2.
220
APPLICABILITY
All
All
All