High/Low Altitude Performance Adjustments
85mitsubishi04SUBJECT:
HIGH/LOW ALTITUDE PERFORMANCE ADJUSTMENTS - SOLD 1985 TRUCKS AND MONTEROS
NO. STB-85-25-004
DATE December, 1985
MODEL 1985 Truck and
Montero
INTRODUCTION A customer who originally purchased a 1985 low-altitude truckor Montero and subsequently moves to a high-altitude area or uses the vehicle in a high altitude area above 4,000-5,000 feet may ask a dealer to make adjustments to improve the vehicle's performance when operated at higher altitudes. Conversely, a high-altitude vehicle brought to a low-altitude area may benefit from adjustments to improve its performance at the lower altitude.
PURPOSE This bulletin contains information needed to perform the adjustments to improve lowor highaltitude performance. These adjustments and-the parts involved are not covered by warranty and are made at the customer's expense.
Please note that the adjustments and parts in this bulletin do not bring a low-altitude vehicle into conformance with high-altitude emissions standards or a high-altitude vehicle into conformance with low-altitude emissions standards and are not intended for this purpose.
VEHICLES AFFECTED The altitude adjustments apply to 1985-model gasoline and diesel trucks. Adjustments to improve performance of 1985 model high-altitude Monteros at lower altitudes are also included in this bulletin (For low/high altitude adjustments on 1985 Monteros, see STB 85-25-001).
PARTS AVAILABLE Two parts packages are available. Their contents are tabulated in Table I on Page 2 of this bulletin.
ADJUSTMENTS Adjustments consist of ignition timing changes coupled with installation on some models of a High Altitude Compensator (HAC) and an Emission Control Information Update Label. Three adjustment procedures are given for gasoline-powered vehicles; two are given for diesel trucks.
The procedures are given first for low-altitude vehicles being adjusted for high-altitude operation and secondly for high-altitude vehicles being adjusted for low-altitude operation. They are tabulated in Table II, Page 2 and begin on Page 2.
ADJUSTMENT PROCEDURES - LOW ALTITUDE --> HIGH ALTITUDE
A. 49-State Gas Trucks -- Low --> High Altitude
1. Set ignition timing:
2.0L: 10~ BTC #2~ 2.6L: 12~ BTC #2~
2. For truck with 2.0L engine, obtain Kit No. MD089717 For truck with 2.6L engine, obtain Kit No. MD089718
FIGURE 1:
FIGURE 2 -- LABEL INSTALLATION ON GAS TRUCKS AND MONTERO -LOW -->HIGH ALTITUDE:
3. Install the kit as shown in the appropriate illustration (Fig. 1, Page 4). Affix the label as shown in Fig. 2, Page 5.
FIGURE 2 -- LABEL INSTALLATION ON GAS TRUCKS AND MONTERO -LOW -->HIGH ALTITUDE:
B. 50-State Gas Trucks -- Low --> High Altitude
1. Set ignition timing:
2.0L: 10~ BTC +/- 2~ 2.6L: 12~ BTC +/- 2~
2. Obtain and install label MD093753 as shown in Fig. 2, Page 5.
FIGURE 3 - LABEL INSTALLATION ON DIESEL TRUCKS - LOW --> HIGH ALTITUDE:
C. Diesel Trucks -- Low --> High Altitude
1. Advance injection timing by 2 degrees to 3 degrees ATC.
2. Obtain and install label MD075095 as shown in Fig. 3, Page 5.
FIGURE 4 - LABEL INSTALLATION, TRUCK HIGH --> LOW ALTITUDE:
FIGURE 5 - LABEL INSTALLATION, MONTERO HIGH --> LOW ALTITUDE:
ADJUSTMENT PROCEDURES -- HIGH ALTITUDE --> LOW ALTITUDE
D. Gas-Engine Trucks and Montero -- High --> Low Altitude
1. Set ignition timing:
2.0L engine: 5 degrees BTC 2.6L engine: 7 degrees BTC
2. Obtain and install the appropriate label:
Truck MD080350 (See Fig. 4, Page 6) Montero MD093754 (See Fig. 5, Page 6)
E. Diesel Trucks -- High --> Low Altitude
1. Set injection timing to 5 degrees ATC.
2. Obliterate the Vehicle Emissions Control Information Update label on the underside of the hood to avoid possible confusion.