Engine - Sag, Stumble, or Surge When Cold
84mitsubishi01SUBJECT:
CORDIA/TREDIA 2.0L ENGINE DRIVEABILITY
NO. STB-84-14-002
DATE February, 1984
MODEL 1984 Cordia/Tredia
INTRODUCTION
This bulletin contains information on modifications that can improve the driveability of early 2.0 liter Cordias and Tredias which exhibit sag, stumble, or surge when cold or after partial cool-down.
MODIFICATIONS REQUIRED
The modifications consist of the following:
^ Replace carburetor primary main air jet
^ Replace coolant temperature sensor
^ Install secondary vacuum orifice
^ Adjust accelerator pump
^ Set ignition timing
^ Set idle speed
^ Place "completion mark" on vehicle
FIGURE 1:
PARTS REQUIRED (Kit #MD085618)
^ #60 primary main air jet
FIGURE 2:
^ Coolant temperature sensor
FIGURE 3:
^ #50 orifice
FIGURE 4:
SPECIAL TOOLS REQUIRED
^ Flat-blade screwdriver with 4-mm. wide blade.
FIGURE 5:
FIGURE 6:
^ Accelerator pump nut adjusting tool made from a screwdriver (Fig. 5) or a 4-mm. deep socket (Fig. 6).
HOW TO DETERMINE WHICH MODIFICATIONS ARE REQUIRED
FIGURE 7:
Remove the air cleaner and inspect the throttle position sensor. If it has a blue or black dot on it (see Figure 7), some or all of the modifications have been performed. If the TPS has a "U" stamped on it, all modifications have been made, and no further modifications are needed.
Driveability modifications were introduced at various times, and therefore you will need to look at the engine number to determine which modifications have been performed on the car you are looking at. The table on the following page shows the engine numbers at which the various modifications become effective. The engine number is at the top of the block near the front.
NOTE: Vehicles produced after January, 1984 will no longer has a "U" marking, but will contain all modifications.
DRIVEABILITY MODIFICATION EFFECTIVE POINTS
FIGURE 8:
CORRECTION PROCEDURE
1. Obtain kit #MD085618.
2. Using the 4-mm. screwdriver, unscrew the primary main air jet. See Figure 8 for location. Install the #60 primary main air jet and discard the old one.
NOTE: The red plastic nozzle extension from a "WD-40" can is a handy tool for removing the jet from the carburetor. Be sure the throttle is closed. Hold the choke shut to keep the jet from dropping down into the carburetor.
FIGURE 9:
3. Use the special accelerator pump adjusting tool you have made to unscrew the accelerator pump nut counterclockwise three (3) full turns. See Figure 9.
NOTE: If you are uncertain whether this operation has already been performed, check to see if the nut is flush with the end of the rod. If it is, then this operation has already been performed.
FIGURE 10:
4. Inspect the coolant temperature sensor mounted on top of the intake manifold. If it has a black center, it is an early unit and must be replaced. See Figure 10. If it has a brown center or is marked with white paint, it is the new unit and does not have to be replaced. To replace the sensor, do the following:
a. Drain enough coolant to bring the level below the temperature sensor.
b. Disconnect the battery ground cable and the sensor harness.
c. Unscrew the temperature sensor.
d. Apply pipe thread sealant to the threads of the replacement sensor and install it. Tighten to 30-39 N-m (22-28 ft.-lbs.) Re-connect the battery cable and replenish the engine coolant.
FIGURE 11:
5. Pull the end of the vacuum line off the secondary throttle depression chamber (vacuum actuator) and insert the #50 orifice as shown in Figure 11. Push the vacuum line back on its nipple.
6. Warm up the engine to normal operating temperature. Turn off all lights and accessories, engine cooling fan OFF, and transmission in neutral or park with parking brake applied. If the car has power steering, be sure the front wheels are straight ahead to avoid any load on the power steering pump.
7. Set ignition timing to 5~ - 7~ BTDC at idle.
8. Set idle speed to specifications shown at right.
9. Mark the TPS with blue or black ink or paint.
10. Install the air cleaner.
IDLE SPEED SPECIFICATTONS - RPM
WARRANTY CLAIM SUBMITTAL
A Warranty Claim (MWC) should be submitted using the standard Warranty Claim form (MSSP-003D-00). The following instructions must be followed to ensure prompt processing and reimbursement.
^ Submit one claim form for each vehicle.
^ Change the top part of each claim form. "White-out" the pre-printed "W" and insert the letter "X" in the same space (see claim example below):
^ Use Labor Operation Code 14-99-10-01.
^ Use Labor Operation Time of 0.5 hr.
^ Use Failure Code 99.
^ Enter the words "PRODUCT MODIFICATION" in the Sublet Information box on the right side of the claim.
^ No other Labor Operation Code may be used on this claim.