Idle Speed -Adjustment Procedures
90isuzu04 BULLETIN NUMBER SB90-01-004ISSUE DATE July 19, 1990
GROUP ENGINE
TROOPER II (KT) ROUGH IIDLE (V6 ENGINE)
AFFECTED VEHICLES
1989-90 Trooper II (KT) models with V6 engine.
SERVICE INFORMATION
An incorrect minimum idle speed may cause affected vehicles to idle poorly. This Service Bulletin describes the procedure for adjusting the minimum idle speed.
SERVICE PROCEDURE
1. Warm engine to normal operating temperature. Then turn ignition key to the "OFF" position.
2. Block the drive wheels and apply the parking brake.
3. Remove the air cleaner. Ensure any disconnected vacuum lines are plugged.
Figure 1:
Figure 2:
4. Connect a Scan tool to the ALDL connector, located in the center console (Figure 1).
NOTE Refer to the Scan tool manufacturer's instructions for tool operation.
5. Turn the ignition key to "ON". Be sure that all accessories (air conditioning, rear defogger, etc.) are turned off.
6. Adjust the throttle position sensor (TPS) as follows:
a. Select "TPS" voltage display on the Scan tool.
b. If necessary, adjust the TPS to obtain 0.48 0.06 volt reading.
c. Tighten the TPS attaching screws just enough to hold the TPS in place.
7. Seat the Idle Air Control (IAC) valve pintle as follows:
a. Select "FIELD SERVICE MODE" on the Scan tool. This will cause the IAC valve pintle to seat in the throttle body, closing the idle air passage.
b. Wait at least 45 seconds, then disconnect the IAC valve electrical connector from the IAC motor. See Figure 2. Exit "FIELD SERVICE MODE" on the Scan tool.
8. Disconnect the distributor set-timing single-pin connector, located near the ECM connector under the center console tray (Figure 1). This will set code 42 in the ECM memory, which must be cleared at the end of this procedure.
9. Place the transmission in neutral. Start and run the engine. Make sure that the throttle and cruise control cables do not hold the throttle open.
10. Select "DATA LIST" on the Scan tool, and enter "ROAD TEST" mode. With the engine idling, check the engine rpm reading. If necesswy, adjust idle speed to 650 +/- 100 rpm as follows (Figure 2):
a. Remove and discard the idle adjustment screw plug.
b. Adjust the idle adjustment screw to obtain an rpm reading of 650 +/- 100 rpm.
11. Turn the ignition key to "OFF."
12. Reconnect the IAC valve electrical connector and the distributor set-timing connector.
13. Turn the ignition key to "ON".
14. Recheck the TPS voltage on the Scan tool.
a. If necessary, readjust the TPS to obtain 0.48 +/- 0.06 volt reading.
b. Torque the TPS attaching screws to 18 in.lbs. Be sure TPS adjustment is not changed after tightening screws.
15. Reset the IAC valve pintle position as follows:
a. Start the engine and run at about 1,000 rpm for five seconds.
b. Turn the ignition key to "OFF" and wait for ten seconds.
c. Restart the engine. Allow the engine speed to stabilize.
d. Check the "IDLE AIR CONTROL" count on the Scan tool. The IAC count should be between 1 and 6.
- If the IAC count is not within specification, repeat steps 7 through 15 of this procedure, but readjust the minimum idle speed (in step 10b) as necessary: Higher to decrease IAC count; lower to increase IAC count.
16. Install a new idle adjustment screw plug. (See "Parts Information" section of this Service Bulletin.)
17. Disconnect the Scan tool. To clear codes from the ECM, remove fuse no. 4 (for models up to VIN K8911295) or fuse no. 6 (for models after VIN K8911295) for 30 seconds, then reinstau fuse.
18. Reinstall the air cleaner.
PARTS INFORMATION
Part No. Description
8-17074-989-0 Idle Adjustment Screw Plug
FLAT RATE MANUAL INFORMATION
Use existing flat rate operation number 020207.