Emission Control - Major Revisions
Category 16Applicable Model/s LISTED BELOW
Subject
MAJOR CHANGES FOR 1984 MODELS
Bulletin No. 184/83
Issued 9/2/83
Revised
DESCRIPTION
This service bulletin contains the major technical changes for the 1984 models listed below.
1. GLC
a. Emission Control System
b. Cooling System
c. Fuel System
2. 626
a. Emission Control System
3. B2000
a. Emission Control System
4. B2200
a. Intake Shutter Valve System
Vacuum Delay Valve and Orifice:
1. GLC
a. EMISSION CONTROL SYSTEM
EGR SYSTEM Vacuum Delay Valve and Orifice
A vacuum delay valve and an orifice have been added to the ATX models to improve driveability. They delay EGR operation during initial acceleration.
Ref. W/S Manual 1A:20 S/B Category 1A 030/83.
Anti-Afterburn Valve:
DECELERATION CONTROL SYSTEM (AAV-Anti-Afterburn Valve)
An anti-afterburn valve has been added to the ATX models to improve driveability during acceleratiom. The AAV allows air into the intake manifold to prevent a rich mixture during deceleration.
Ref: W/S Manual 1A:23
Cooling Fan:
b. COOLING SYSTEM
The operating temperatures for the cooling fan switch and thermostat have been changed to improve driveability during extreme hot weather operation.
84 83
Water Temperature Switch
91~c 97~c
(Cooling Fan) on above
Thermostat
82~c 88~c
(Engine Coolant) open above
Fuel Return Line:
GLC (cont.)
c. FUEL SYSTEM Fuel Return Line
On the 1984 model GLC, fuel returns to the fuel tank from the carburetor and not from the fuel pump as in previous years. This improves driveability during hot under hood conditions.
Ref: W/S Manual 4:9 S/B: Category 4 046/83
Check Valve
With the above change, a fuel check valve has been added in the fuel return line to prevent fuel from flowing back into the carburetor from the fuel tank.
EGR SYSTEM - Vacuum Delay Valve and Orifice:
2. 626
a. EMISSION CONTROL SYSTEM
EGR SYSTEM Vacuum Delay Valve and Orifice
A vacuum delay valve and an orifice have been added to the ATX models in the vacuum line to the duty solenoid valve to improve driveability. It delays EGR during initial acceleration.
Ref: W/S Manual 1A:17 S/B Category 1A 033/83
AIR INJECTION SYSTEM (FEDERAL) - Reed Valves:
3. B2000
a. EMISSION CONTROL SYSTEM
AIR INJECTION SYSTEM (FEDERAL) Reed Valves
Two reed valves are now used on Federal M/T models and three reed valves are used on federal A/T models to aid in the reduction of HC & CO.
Ref: W/S Manual 4A:33
EGR SYSTEM (FEDERAL):
B2000 (cont.)
EGR SYSTEM (FEDERAL)
Two EGR valves are used on B2000 Federal Models for more precise control of EGR. The EGR solenoid valve will cut vacuum to the No. 2 EGR valve when radiator temperature is below 17~ +/- 2~c (63~ +/- 3.6~F) or when intake manifold temperature is below 50~ +/- 2~c (122~ +/- 36~F).
Ref: W/S Manual 4A:38
THROTTLE POSITIONER SYSTEM - (FEDERAL A/T):
B2000 (cont.)
THROTTLE POSITIONER SYSTEM (FEDERAL A/T)
Double Acting Servo Diaphragm Water Thermo Switch (Rad) Fast Idle Solenoid Valve
The fast idle solenoid is controlled by the water thermo switch (intake manifold), control unit and water thermo switch (radiator). When radiator coolant temperature is below 17~C (63~F), intake manifold coolant temperature is below 67~C (152~F) and engine rpm is below 1500 rpm, vacuum will be applied to the servo diaphragm through hose "B" and engine speed should increase to 1300 +/- 100 rpm.
Ref: W/S Manual 4A:95
THROTTLE POSITIONER SYSTEM (CANADA A/T) - Water Thermo Switch:
B2000 (cont.)
THROTTLE POSITIONER SYSTEM (CANADA A/T) Water Thermo Switch
A water thermo switch located in the intake manifold has been added to the Throttle Positioner System. (When engine coolant temperature is below 55~ +/- 2~C (131~ +/- 36~F) the thermo switch will open and increase engine idling speed to 1100 rpm).
Ref: W/S Manual 4A:42
PRIMARY AIR SUPPLY SYSTEM - (FEDERAL):
B2000 (cont.)
PRIMARY AIR SUPPLY SYSTEM (FEDERAL)
A Primary Air Supply System has been adopted on Federal Models only, to lean the mixture when:
Radiator Coolant Temperature above 17~C (63~F), Intake Manifold Coolant Temperature below 50~C (122~F) and engine rpm is above 1200 rpm.
Ref: W/S Manual 4A:51
4. B2200
a. INTAKE SHUTTER VALVE SYSTEM
The intake shutter valve has been eliminated.