Throttle - Sticking in Closed Position
05.1-23DATE
9/96
Amended 8/97
Throttle Deposits/Sticking Closed -
AJ16 Engines - Revised Idle Speed
Adjustment Procedure
MODEL
1995-97 MY
Sedan (4.0L) Range
VIN
720001-812255
Remove and destroy Bulletin 05.1-23, dated 9/96.
Replace with this Bulletin.
**Revisions are marked with asterisks.**
ISSUE:
Some 1995-97 MY Sedan (4.0L) Range vehicles may experience intermittent sticking of the throttle in the closed position. Greater throttle pressure than usual may be required to open the throttle. This condition is most likely to occur when the engine is first started after standing overnight.
The cause has been identified as a build-up of carbon deposits on the throttle and venturi area. The deposits reduce the air-gap and cause the throttle to stick closed. Idle speed is not affected since the Idle Air Control Valve (IACV) compensates.
ACTION:
In case of a customer complaint of the throttle sticking closed on a 1995-97 MY Sedan Range vehicle, check the position of the idle air control valve stepper motor and then adjust the idle stop screw, as necessary, to reset the throttle closed position.
**CHECKING POSITION OF IDLE SPEED STEPPER MOTOR
1. Drive the vehicle until coolant and engine oil temperatures have risen to normal operating temperatures.
2. Load Data logger into the PDU at the base station by selecting Diagnostics from the main menu, then Toolbox, Powertrain, and Datalogger.
3. Connect the PDU to the vehicle.
4. Ensure that all nonessential accessories, such as Air Conditioning, fans, heated rear window, seat heaters, lamps, etc. are OFF
5. Ensure that the transmission is in Park or Neutral.
6. From Datalogger, select AJ16 Engine Management. Then select idle stepper motor position (ISCPOS).
If the stepper motor position is 40 steps or more, adjust the throttle idle stop screw as described in this bulletin.**
ADJUSTING IDLE STOP SCREW
1. Switch the engine OFF
2. Turn the stop screw in 1/4 turn using a 2.5 mm Allen wrench.
On naturally aspirated engines, the stop screw is located on the front face of the throttle body assembly, to the rear of the No. 3 cylinder intake manifold runner (Illustration 1).
On supercharged engines, the stop screw is on the bottom side of the throttle body assembly, slightly in front of the oil filter. A mirror and flashlight may be necessary (Illustration 2).
3. Restart the engine and allow a few seconds for the idle speed to stabilize.
4. Restart Datalogger mode of the PDU.
5. Check the idle speed stepper motor position using the PDU. The position should be 25 - 30 steps. If not, repeat steps 1 - 5.
6. Road test the vehicle to determine if throttle sticking still occurs.
7. Use the PDU to check that the idle speed is as follows:
700 RPM in Park/Neutral; 580 RPM in drive positions
Idle speed +/- 30 RPM when the coolant temperature is less than 86°F (30°C)
Idle speed +/- 20 RPM when the coolant temperature is 86°F (30°C) or higher.
8. Disconnect the PDU from the vehicle and reconnect it to the base station.
WARRANTY INFORMATION:
FAULT R.O.
CODE NUMBER DESCRIPTION TIME ALLOWANCE
CD KF NS 19.91.47 Adjust idle speed 0.60 hrs.