(EGR) Systems - Functional Diagnosis
19896-11 Exhaust Gas Recirculation (EGR) Systems
Functional Diagnosis
PORTED EGR VALVE
1. Make certain that all vacuum hoses are correctly routed and securely attached. Replace cracked, crimped or broken hoses.
2. Make certain there is no vacuum to the EGR valve at idle with the engine at normal operating temperature.
3. Install a tachometer, Rotunda 059-00010 or equivalent.
4. Disconnect the Idle Air Bypass Valve (9F715) electrical connector (EFI engines only).
5. Remove the vacuum supply hose from the EGR valve nipple. Plug the hose.
6. Start engine, idle with transmission in NEUTRAL, and observe the engine idle speed. If necessary, adjust idle speed according to Section 4.
7. Slowly apply 5-10 inches of mercury vacuum to the EGR valve vacuum nipple using a hand vacuum pump, Rotunda 021-00014 or equivalent.
8. When vacuum is fully applied to the EGR valve:
^ If idle speed drops more than 100 rpm or if engine stalls, perform the next step. Otherwise, for vacuum leak at EGR valve, replace the valve.
^ If EGR passages are blocked, clean the valve using Rotunda 021-80056 EGR valve cleaner.
^ Remove the vacuum from the EGR valve. If idle speed does not return to normal (+/- 25 rpm), check for contamination, clean the valve.
^ Make sure there is no sand left in the valve or pick-up tube. Replace the valve if necessary.
9. Reconnect the idle air bypass valve electrical connector.
10. Unplug and reconnect the EGR vacuum supply hose.
11. The EGR system is OK, refer to the Diagnostic Routines in Section 2.
1989
6-12 Exhaust Gas Recirculation (EGR) Systems
Functional Diagnosis
ELECTRONIC EGR (EEGR) VALVE
1. Make certain that all vacuum hoses are correctly routed and securely attached. Replace cracked, crimped or broken hoses.
2. Make certain there is less than 2.5 in-Hg vacuum to the EGR valve at idle with the engine at normal operating temperature.
NOTE: The EVR solenoid has a constant internal leak. You will notice a small vacuum signal. This signal should be less than 1.0 in-Hg at idle.
3. Install a tachometer, Rotunda 059-00010 or equivalent.
4. Disconnect the Idle Air Bypass Valve (9F715) electrical connector (1.9L EFI engines only).
5. Remove the vacuum supply hose from the EGR valve nipple. Plug the hose.
6. Start engine, idle with transmission in NEUTRAL, and observe the engine idle speed. If necessary, adjust idle speed according to Section 4.
7. Slowly apply 5-10 inches of mercury vacuum to the EGR valve vacuum nipple using a hand vacuum pump, Rotunda 021-00014 or equivalent.
8. When vacuum is applied to the EGR valve and any of the following occur:
^ Engine does not stall
^ Idle speed does not drop more than 100 rpm
^ Idle speed does not return to normal (+/- 25 rpm) after the vacuum is removed
Then:
^ For vacuum leak at EGR valve, replace the valve.
^ Check for contamination, clean the EGR valve, using Rotunda 021-80056 EGR valve cleaner or equivalent.
^ Make sure there is no sand left in the valve.
^ Replace the EGR valve if necessary.
9. Reconnect the idle air bypass valve electrical connector. Unplug and reconnect the EGR vacuum supply hose.
10. If EGR valve is OK, REPLACE EVP sensor if Continuous Code 32 was present. If the Continuous Code 32 was not present, refer to the Diagnostic Routines in Section 2.