Wrangler L4-150 2.5L VIN H TBI (1986)
Idle Speed/Throttle Actuator - Electronic: Adjustments
Fig. 1 Diagnostic connector terminal identification
Adjustment of the ISA motor is only necessary to establish the initial position of the ISA plunger after the motor has been removed and installed or
replaced. Engine idle speed and deceleration throttle stop angle are controlled by an Idle Speed Actuator (ISA) motor. ISA motor operation is controlled
by the ECU which provides appropriate voltage outputs to produce the idle speed or throttle angle required for engine operating conditions. Idle speed is
not adjustable. However, if the ISA motor or throttle body is removed for service the initial position of the plunger should be adjusted using the
following procedure.
1.
Remove air filter assembly, start engine and run until it reaches normal operating temperature.
2.
Ensure that A/C switch (if equipped) is in off position, then connect suitable tachometer to diagnostic connector terminals D1-1 and D1-3, Fig. 1.
3.
Turn ignition switch to off position while observing ISA plunger. Plunger should move to fully extended position.
4.
With plunger in fully extended position, disconnect electrical connector to ISA motor and start engine.
5.
Adjust engine speed to 3500 RPM by rotating hex screw on end of plunger.
6.
Fully retract ISA motor by pressing end of plunger inward while throttle is opened, then release throttle.
7.
Ensure that clearance exists between end of plunger and throttle lever. If lever is contacting plunger, check and repair throttle linkage as needed.
8.
Reconnect electrical connector to ISA motor, then turn ignition switch off for 10 seconds. ISA plunger should move to fully extended position.
9.
Start engine. Engine should run at 3500 RPM for brief period, then return to normal idle speed.
10.
When adjustment is correct, apply suitable thread locking compound to plunger adjuster screw threads.
