Engine Controls - Adjustments - Gasoline Dodge Caravan II

INTRODUCTION - ENGINE MECHANICAL

Note. Adjsutment procedures for Compressed Natural Gas fueled vehicles are not available.

Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.

VALVE CLEARANCE

Note. All engines use hydraulic lifters. No adjustments are required.

IGNITION TIMING

Note. Always refer to emission control information label in engine compartment before service. If manual and emission label differ, use emission label specifications. Basic timing is not adjustable on 3.3L, 3.9L and 5.2L.

2.5L, 3.0L & 5.9L

1. Connect a suitable timing light to No. 1 cylinder. Refer to equipment manufacturer's instructions for proper connection. Turn selector switch to appropriate cylinder position.
2. Start engine, and warm it to normal operating temperature. Connect tachometer, and ensure idle RPM is within specification. (Scheme 1) Attach Air Metering Fitting (6457) to manifold-mounted idle purge hose. Orifice size is.125" (3 mm). Connect Diagnostic Readout Box II (DRB-II) to vehicle.
3. Start engine. Let engine idle for at least one minute. Using DRB-II, access MINIMUM AIRFLOW IDLE SPEED. When this mode is accessed, AIS motor will fully close, spark advance will fix, fuel delivery will not change and engine RPM will be displayed on DRB-II.
4. Check minimum airflow. See «MINIMUM AIRFLOW IDLE SPEED»(/dodge/caravan/ii-1990-1995/remont/adjustments/#engine-controls-adjustments-gasoline) table. If minimum airflow idle speed is not within specification, replace throttle body.

Scheme 1

MINIMUM AIRFLOW IDLE SPEED

3.9L & 5.2L Gasoline

1. Set parking brake, and block front wheels. With engine off, disconnect AIS motor connector at throttle body. Connect Exerciser Tool (7558) harness connector to AIS motor. Connect Red clip of exerciser tool to positive battery terminal. Connect Black exerciser tool clip to negative battery terminal. Red light on exerciser tool will glow when tool is connected properly.
2. Start engine. With exerciser tool switch in HIGH or LOW position, Red tool light will flash. Move switch to HIGH position (engine speed should increase). Move switch to LOW position (engine speed should decrease). If engine speed changes, AIS motor is operating properly. Reconnect AIS motor connector at throttle body. If engine speed changes, test is complete. If engine speed does not change, go to next step.
3. DO NOT disconnect exerciser tool. Turn ignition to OFF position. Remove AIS motor from throttle body. CAUTION: While testing AIS motor operation with AIS motor removed from throttle body, ensure pintle does not extend more than .250" (6.35 mm) from AIS motor body.
4. Cycle exerciser tool switch between HIGH and LOW positions and observe pintle. If pintle does not move, replace AIS motor. If pintle moves, check throttle body bore for blockage and clean as necessary. Install AIS motor, and retest system. If no blockage exists, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.

THROTTLE POSITION SENSOR (TPS)

Note. Throttle Position Sensor (TPS) is not adjustable. Following procedures may be used to check TPS calibration.

1. Turn ignition switch to ON position. DO NOT start engine. Measure voltage at center terminal of TPS, with throttle valve fully closed against stop. Voltage should be within specification. See «THROTTLE POSITION SENSOR VOLTAGE TEST»(/dodge/caravan/ii-1990-1995/remont/adjustments/#engine-controls-adjustments-gasoline) table. If voltage is not within specification, replace TPS.
2. Slowly open throttle valve to wide open throttle. TPS voltage should gradually increase to at least 3.4 volts. If voltage does not gradually increase to at least 3.4 volts, replace TPS.

THROTTLE POSITION SENSOR VOLTAGE TEST

See also:
• MINIMUM AIRFLOW IDLE SPEED