Bronco L6-300 4.9L VIN Y 1-bbl (1983)
Shift Modulator: Technical Service Bulletins
High Altitude Service Adjustments
Article No. 83-7-24
ALTITUDE - SERVICE ADJUSTMENTS TO SEA LEVEL ENGINE CALIBRATIONS OPERATED AT ALTITUDE - 4.9L ENGINE
LIGHT TRUCKS 1983 E, F AND BRONCO
CALIBRATIONS: Sea Level Calibrations Only.
Customers who may have relocated and/or continually operate the subject vehicles in high altitude (above 4,000 feet altitude) may have the following
procedure performed to improve performance:
4.9L Engines in Vehicles under 8500 Lb. GVW
1.
Replace PCV valve E-111 (E0TE-6A666-AA) with a new PCV valve EV-49 (D8TZ-6A666-B).
2.
Advance ignition timing 4~ from specification on Vehicle Emission Control Decal by referring to procedure outlined in pertinent Truck Shop
Manual.
3.
Remove existing transmission vacuum diaphragm and install altitude compensating diaphragm and clip (Part No.
D8AZ-7A377-A)(D7FZ-7F006-A)(C6 transmission) as outlined in the Light Truck Chassis Manual 17-01-22.
NOTE:
Step 3 does not apply to manual transmission vehicles.
4.
Check and reset idle speeds, if necessary, per Vehicle Emission Control Decal.
Obtain a Vehicle Emission Control Information Update Label (available at all Ford or Lincoln-Mercury dealers) and fill in the appropriate information.
In the top paragraph of the label, cross off the altitude (HIGH or LOW) that does not apply and enter the number of the Technical Service Bulletin and
Article number that provided the modification instructions. Write in the remarks as illustrated in the appropriate Article, including the new specifications
where a space has been provided and the actual numbers have been left blank. At the bottom of the label, enter the date the modification was performed.
Select a prominent place adjacent to the Vehicle Emission Control Information decal suitable for installing the label. Do not install the label on any
component that can be easily detached from the vehicle. Clean the area, install the label and cover it with a clear plastic decal shield.
NOTE:
The Vehicle Emission Control Information Update Label is a new label to be used for altitude modifications. Do Not use the Authorized
Modifications Label which is used to indicate other types of modifications.
If the vehicle is returned to continuous sea level (below 4,000 feet altitude) operation, the above procedures should be reversed and the Vehicle Emission
Control Information Update Label should be removed from the vehicle.
4.9L Vehicles over 8500 Lb. GVW Calibrations; 9-77J-R12, 9-78J-R00 9-77S-R10, 9-78J-R11
1.
Remove the PCV valve EV-76 (D8DE-6A666-AA) and replace it with a new PCV valve EV-77 (D8TZ- 6A666-A).
2.
Advance ignition initial timing to 4~ advanced over sea level specification.
3.
Remove existing transmission vacuum diaphragm and install altitude compensating diaphragm and clip (Part No.
D8AZ-7A377-A)(D7FZ-7F006-A)(C6 transmission) as outlined in the Light Truck Chassis Manual 17-01-22.
NOTE:
Step 3 does not apply to manual transmission vehicles.
