Conversion of Low Altitude System to High Altitude

Dealers in high altitude areas should encourage owners who have moved to high altitude counties to purchase the service adjustment procedure outlined below, which is considered an owner maintenance expense. See attachment for a list of counties which the Environmental Protection Agency has designated as high altitude counties.

EGR VALVE VACUUM CONTROL ASSEMBLY:

1. Replace the EGR valve vacuum control assembly (Fig. 1) with the assembly shown in the parts information.
2. Install magnetic tachometer probe, run engine until it is at operating temperature. Set idle speed to specifications, turn engine off.

3. Remove air cleaner and air crossover assemblies and install screen covers J-26996-2.

FIGURE 2:

4. Install shop towel in the intake manifold valley area under the injection pump to absorb any fuel leakage. Remove housing pressure tap plug and seal located on the rear of the pump (Fig. 2).
5. Assemble locknut and new seal (O-ring) to metering valve stop screw as shown.

6. Install assembly in injection pump until locknut contacts pump housing. Tighten locknut.
7. Place transmission in park, turn A/C off and start engine.

8. Loosen locknut and slowly turn metering valve stop screw clockwise until idle speed drops approximately 10 RPM.

9. Turn metering valve stop screw counterclockwise 3 turns on Estate wagons and 2-1/2 turns on all except Estate wagons and tighten locknut.

10. Check installation for fuel leaks and remove shop towel from intake valley.

11. Turn engine off.

12. Remove magnetic tachometer probe and screened covers from intake manifold and reinstall parts removed.

VEHICLE EMISSION CONTROL INFORMATION UPDATE GENERAL MOTORS CORPORATION:

13. Type or print with ball point pen the dealer code and date in the space provided on the supplemental emission control label, part number 14057201 or equivalent, Figure 3 (part of kit). The label must be placed next to the existing underhood emission control information label to the extent possible. The label should not be affixed to any equipment that can be easily detached from the vehicle. Wash off the area with soap and water, dry thoroughly, and apply the new label.