Engine - Altitude Performance Adjustments
Number: 83-I-71Section: VIt
Date: May, 1983
Subject: 1983 MONTE CARLO ALTITUDE PERFORMANCE ADJUSTMENTS 4.3L V6 DIESEL ENGINE
TO: ALL CHEVROLET DEALERS
1983 Monte Carlo models 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.
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 following adjustment procedure. This adjustment is considered an owner maintenance expense. See attachment for a list of counties which the Environmental Protection Agency has designated as high altitude counties. Diesel timing should be checked or adjusted at the same approximate altitude at which the vehicle will be driven.
FIGURE 1 - EGR VALVE VACUUM CONTROL ASSEMBLY:
1. Replace the EGR vacuum control valve assembly with the assembly shown in Figure 1. 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.
4. With transmission in park and A/C off, start engine.
FIGURE 2 - LOCK NUT:
5. Loosen lock nut (Figure 2) and slowly turn metering valve stop screw. clockwise until idle speed drops approximately 10 rpm.
6. Turn metering valve stop screw counterclockwise exactly 2 1/8 turns. Tighten lock nut.
7. Check for fuel leaks around metering valve stop screw.
8. Turn engine off.
9. Remove magnetic tachometer probe and screened covers from intake manifold and reinstall parts removed.
FIGURE 3 - VEHICLE EMISSION CONTROL INFORMATION UPDATE:
10. Fill in dealer code and date on the supplemental emission control label, P/N 14057201 or equivalent (Figure 3). This 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 P/N
1. EGR Vacuum Control Valve Assembly High Altitude
Application 22519396 or equivalent
2. Label 14057201 or equivalent
SUGGESTED TIME
The suggested time to perform the Low to High Altitude Adjustment and part replacement is 0.8 hour labor.
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 checked or adjusted at the same approximate altitude at which the vehicle will be driven.
FIGURE 1 - EGR VALVE VACUUM CONTROL ASSEMBLY:
1. Replace the EGR vacuum control valve assembly with the assembly shown in Figure 1. 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 2 - LOCK NUT:
4. Loosen lock nut (Figure 2) and turn metering valve stop screw counterclockwise 1.5 turns. Tighten lock nut.
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 - VEHICLE EMISSION CONTROL INFORMATION UPDATE:
8. Fill in dealer code and date on the supplemental emission control label, P/N 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 P/N
1. EGR Vacuum Control Valve Assembly Low Altitude
Application 22519395 or equivalent
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.
DESIGNATED HIGH ALTITUDE COUNTIES* Requiring High Altitude Emission Control
STATE OF ARIZONA Apache Navajo
STATE OF COLORADO
Adams Jefferson
Alamosa Lake
Arapahoe La Plata
Archuleta Larimer
Boulder Las Animas
Chaffee Lincoln
Clear Creek Mesa
Conejos Mineral
Costilla Moffat
Crowley Montezuma
Custer Montrose
Dolores Morgan
Delta Ouray
Denver Park
Douglas Pitkin
Eagle Pueblo
Elbert Rio Blanco
El Paso Rio Grande
Fremont Routt
Garfield Saguache
Gilpin San Juan
Grand San Miguel
Gunnison Summit
Hinsdale Teller
Huerfano Washington
Jackson Weld
STATE OF IDAHO
Bannock Custer
Bear Lake Franklin
Bingham Fremont
Blaine Jefferson
Bonneville Madison
Butte Minidoka
Camas Oneida
Caribou Power
Cassia Teton
Clark Valley
STATE OF MONTANA
Beaverhead Madison
Dear Lodge Meagher
Gallatin Park
Jefferson Silver Bow
STATE OF NEBRASKA
Banner Sioux
Kimball
STATE OF NEVADA
Carson City Humboldt
Douglas Lander
Elko Lyon
Esmeralda Mineral
Eureka Storey
White Pine
STATE OF NEW MEXICO
Bernalillo Mora
Catron Rio Arriba
Colfax Sandoval
Curry San Juan
De Baca San Miguel
Grant Santa Fe
Harding Socorro
Lincoln Taos
Los Alamos Torrance
Luna Union
McKinley Valencia
STATE OF OREGON
Lake
STATE OF UTAH
Beaver Piute
Box Elder Rich
Cache Salt Lake
Carbon San Juan
Daggett Sanpate
Davis Sevier
Duchesne Summit
Emery Tooele
Grand Uintah
Iron Utah
Juab Wasatch
Kane Wayne
Millard Weber
Morgan
STATE OF WYOMING
Albany Natrona
Carbon Niobrara
Converse Park
Fremont Platte
Goshen Sublette
Hot Springs Sweetwater
Johnson Teton
Laramie Uinta
Lincoln Weston
* Counties which have substantially all of their area above 4000 ft. Ref. Federal Register, Vol. 42, No. 76, April 20, 1977, pg. 20464
EPA DESIGNATED HIGH ALTITUDE COUNTRIES (Shaded area indicates high altitude):
EPA DESIGNATED HIGH ALTITUDE COUNTRIES
(Shaded area indicates high altitude)