ECU - Driveway Die Outs With A Cold Engine

89AMCjeep13

Models

1987-1990 MJ & XJ Bodies With 4.0 Liter Engine


Subject

Start and Stall and Driveway DieOut


Index


DRIVEABILITY


Date

December 29, 1989


No.


18-54-89 REVISION A

P-0005 (C18-24-9)
BODY CODE LEGEND

MJ - COMANCHE XJ - CHEROKEE


NOTE: THIS TECHNICAL SERVICE BULLETIN SUPERCEDES TSB 18-54-89 WHICH SHOULD BE REMOVED FROM YOUR FILES.


SYMPTOM/CONDITION

Driveway die-outs with a cold engine, particularly in warm ambient temperatures.


DIAGNOSIS

Verify that TSB 18-51-88 or TSB 18-57-89 (crank position sensor and patch harness) has been properly performed on the vehicles to which they apply. Make sure the fuel management system is operating correctly by using the DRB II in the state display and systems test. Any electronic engine control problems detected by the DRB II must be corrected before performing this TSB.


PARTS REQUIRED

1 ECU (Automatic Transmission) PN 53007842
1 ECU (Manual Transmission) PN 53007843
1 Mopar Choke and Linkage Cleaner PN 4549619
REPAIR PROCEDURE


This repair procedure involves replacing the ECU and cleaning the throttle body.


1. Install the new service replacement ECU.


2. With the engine off, remove the clean air tube from the throttle body.


3. Open the throttle and spray the bottom edge of the throttle plate and the throttle body bore with Mopar Choke and Linkage Cleaner, PN 4549619, (use cleaner sparingly).

NOTE: USE ONLY THE RECOMMENDED CLEANER TO PREVENT DAMAGE TO THE THROTTLE SHAFT SEALS.


4. Using a soft bristle brush such as a tooth brush, work the cleaner into the stubborn deposits on the throttle blade and the throttle body bore where the throttle blade is positioned at idle. Allow the cleaner to soak for three (3) minutes.


5. Start the engine and let idle. Spray the cleaner sparingly at the throttle plate edge and throttle bore contact area.


6. Operate the engine at 1500 RPM for one minute to clear the intake manifold of cleaner. Allow the engine to idle until it reaches normal operating temperature. Then shut the engine off.


7. With the engine off, connect the DRB II to the vehicle.


8. Disconnect the idle speed stepper motor wire harness connector at the stepper motor.

Figure 1:

9. Connect the stepper motor exerciser tool 7558 (Ele. CT01) to the stepper motor. See Figure 1.
10. Set the parking brake, place the transmission in park or neutral and start the engine.

11. While observing the RPM on the DRB II, put the exerciser tool control switch in the low position until minimum idle speed is obtained.

12. With all accessories off, adjust the base engine idle speed to 575 rpm in neutral. This should be accomplished by first adjusting the throttle body air by-pass screw and then, if necessary, by adjusting the throttle stop screw.

13. Adjust the throttle position sensor so that the "state display" on the DRB II displays the throttle position sensor as 12-14%. If the TPS percentage is above or below this number, refer to the TPS adjustment procedures as displayed on the DRB II or as outlined in the appropriate Jeep Service Manual.

Figure 2:

14. Shut the engine off. Install the clean air tube, remove the stepper motor exerciser control tool, connect the idle speed stepper motor wire connector. Spray the exposed threads of the throttle stop screw with cleaner and blow dry with shop compressed air. Apply Loctite 209 or equivalent to the exposed threads. See Figure 2.
POLICY: Reimbursable within the provisions of the warranty.


TIME ALLOWANCE:
Labor Operation No. 08-15-62-93 . . . . . . . . . . . . . . . . . 1.0 Hrs.


FAILURE CODE: 04 - Cold Stall