Conversion of High Altitude System to Low Altitude

Dealers should advise owners moving to low altitude areas that they should purchase the following altitude adjustment procedure. This adjustment is considered an owner maintenance expense. Diesel timing should be check or adjusted at the same approximate altitude at which the vehicle will be driven.

FIGURE 2:

1. Replace the EGR vacuum control valve assembly with EGR vacuum control valve assembly part number 22519395 or equivalent. Refer to Figure 2.

FIGURE 1:

2. Install a vacuum modulator valve, part number 563494 or equivalent, in the location as shown in Figure 1. A rubber block connector, "F" connector and elbow connector will also be required to convert to the low altitude system as shown in Figure 1. Additional vacuum hose may also be required. The part numbers for all parts required are listed in the Parts Section of this bulletin.
3. Reroute the vacuum hoses and install the above parts as indicated in Figure 1.

4. Install Timing Meter J-33075 or equivalent, set pump timing to -6~, and set idle speed to specifications. Turn off engine.
5. Remove air crossover assembly. Install screen covers J-29657.

FIGURE 3:

6. Loosen lock nut (Figure 3) and turn metering valve stop screw counterclockwise 1.5 turns. Tighten lock nut.
7. Start engine. With engine running and transmission in park, check for fuel leaks around metering valve stop screw. Turn engine off.
8. Remove magnetic tachometer probe and screened covers from intake manifold and reinstall air crossover and air cleaner.

FIGURE 5:

9. Fill in dealer code an date on the supplemental emission control label, part number 14055121 or equivalent (Figure 5). The label must be placed next to the existing underhood emission control information label. Wash off the area with soap and water, dry thoroughly and apply the new label.

PARTS INFORMATION

Part Part Number
1. EGR Vacuum Control Valve 22519395 or equivalent Assembly - Low Altitude Application
2. Vacuum Modulator Valve 563494 or equivalent
3. "F" Connector 22502326 or equivalent
4. Elbow Connector 556992 or equivalent
5. Rubber block connector 560840 or equivalent
6. Vacuum Hose (bulk) 9438381 or equivalent
7. Label 14055121 or equivalent

Suggested Time

The suggested time to perform High to Low Altitude adjustment and part replacement is 0.8 hour labor.


B. 4.3L .V6 DIESEL ENGINE VIN CODE "V"

1983 Regals equipped with 4.3L V6 diesel engines will be manufactured with either high or low altitude diesel emission systems. Cars equipped with the high altitude emission system will be invoiced with option NA6. The type of system can also be identified by the emission label attached to the fan shroud. The label will indicate that the car was built for primary use at either high or low altitude. These procedures are considered altitude performance adjustments and apply only to in-use vehicles. They should not be used to modify vehicles prior to sale.
Dealers should advise owners moving to low altitude areas that they should purchase the following altitude adjustment procedure. This adjustment is considered an owner maintenance expense. Diesel timing should be checked or adjusted at the same approximate altitude at which the vehicle will be driven.

FIGURE 8:

1. Replace the EGR vacuum control valve assembly with the assembly shown in Figure 8. Refer to Parts Information for part numbers.
2. Install timing meter J-33075 or equivalent, set pump timing to -6~, and set engine idle to specifications, turn off engine.
3. Remove air crossover assembly. Install screen covers J-29657.

FIGURE 9:

4. Loosen locknut (Figure 9) and turn metering valve stop screw counterclockwise 1.5 turns. Tighten locknut.

5. Start engine. With engine running and transmission in Park, check for fuel leaks around metering valve stop screw.
6. Turn engine off.
7. Remove magnetic tachometer probe and screened covers from intake manifold and reinstall parts removed.

FIGURE 4:

8. Fill in dealer code and date on the supplemental emission control label, part number 14055121 or equivalent (Figure 4). The label must be placed next to the existing underhood emission control information label. Wash off the area with soap and water, dry thoroughly and apply the new label.
PARTS INFORMATION

Part Part Number
1. EGR Vacuum Control Valve Assembly 22519395 or equivalent Low Altitude Application
2. Label 14055121 or equivalent

Suggested Time

The suggested time to perform High to Low Altitude adjustment and part replacement is 0.8 hour labor

C. 5.7L V8 DIESEL ENGINE VIN CODE "N"

The 1983 Buicks equipped with 5.7L V8 diesel engines will be manufactured with either high or low altitude diesel systems. A vehicle with a high altitude system will be invoiced with option NA6. The type of system can also be identified by the emission label attached to the fan shroud. The label will indicate that the vehicle was designed for principal use at either high or low altitude.

These adjustments are considered Altitude Performance Adjustments and apply only to in-use vehicles. They should not be used to modify vehicles prior to sale.
Dealers must not sell vehicles with low altitude systems for principal use at high altitude.