Hot Engine Test

NOTE: The engine must be at the normal operating temperature (cooling fan should come on at least once).
1. Disconnect the vacuum hose from the EGR valve and connect a vacuum gauge to the hose, Fig. 62.
2. Open the vacuum control box to gain access to individual components.
a. Remove the vacuum control box from the firewall by first removing the two attachment bolts,
b. Remove the four screws that secure the cover to gain access to the individual components.

Setup For Test Condition 3:

3. Vacuum to the EGR valve should be as follows:

At idle No vacuum
3000 rpm 70 - 200 mbar (2 - 6 in. Hg)
3000 rpm with blocked vacuum bleed, Fig. 63 less than 70 mbar (2 in. Hg)
During rapid Acceleration 70 - 200 mbar (2 - 6 in. Hg)
During deceleration No vacuum

4. If vacuum is available at idle:
a. Check the vacuum hoses for correct routing, and good connections.
b. Check for correct idle speed, and adjust as necessary.
c. Check for correct idle mixture, and adjust as necessary.
5. If there is no vacuum at 3000 rpm or during rapid acceleration, check thermovalve A.
a. Disconnect the #18 vacuum hose from thermovalve A.
b. Connect a vacuum gauge to the hose and check for vacuum (at 3000 rpm and during rapid acceleration).
c. If there is no vacuum, check the routing of the #18 vacuum hose and its connections. Check the vacuum orifices for blockages. Repair as necessary.
d. If vacuum is available, replace thermovalve A and retest.
6. If more than 70 mbar (2 in. Hg) of vacuum is available at 3000 rpm with the vacuum bleed blocked:
a. Check the hoses for correct routing and good connections.
b. If the hoses are OK, replace the EGR control valve and retest the system.