Engine Controls - Adjustments - 2.4L Dodge Caravan III

ENGINE MECHANICAL

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

VALVE CLEARANCE

Note. Engine uses hydraulic lifters. No adjustments are required.

IGNITION TIMING

Ignition timing is controlled by Powertrain Control Module (PCM) and is non-adjustable.

IDLE SPEED & MIXTURE

Idle speed/mixture controlled by Powertrain Control Module (PCM). No adjustment required. The PCM controls Idle Air Control (IAC) motor for proper idle speed. See TESTS W/CODES - 2.4L article for diagnosis of incorrect idle speed or IAC motor operation.

THROTTLE BODY MINIMUM AIRFLOW

Note. Throttle body minimum airflow procedure checks throttle body calibration for correct idle speed. Procedure may be used for idle speed problems caused by the throttle body. Throttle body minimum airflow procedure should be performed after all other diagnostic procedures have failed to produce results that indicate a throttle body related problem. Ensure IAC motor is operating correctly before performing this procedure.

Scheme 1

1. Start and warm engine to normal operating temperature until electric cooling fan cycles on and off at least once. Ensure all accessories are off. Shut engine off.
2. Disconnect PCV valve vacuum hose from intake manifold. Place cap on PCV valve vacuum hose fitting on intake manifold. Disconnect idle purge hose from throttle body. This is vacuum hoses that goes to EVAP purge solenoid. Install.125" fixed orifice Air Metering Fitting (6457) on idle purge vacuum hose fitting on throttle body.
3. Connect scan tool to Data Link Connector (DLC), located below driver's side of instrument panel, to the left of steering column. (Scheme 1)
4. Start and warm engine to normal operating temperature until electric cooling fan cycles on and off at least once. Using scan tool manufacturer's instructions, access MINIMUM AIRFLOW display on scan tool.
5. When accessed, scan tool will display minimum airflow idle RPM. Minimum airflow idle RPM should be within specification. See THROTTLE BODY MINIMUM AIRFLOW IDLE SPEED SPECIFICATIONS table. THROTTLE BODY MINIMUM AIRFLOW IDLE SPEED SPECIFICATIONS Application (1) RPM 1000 Miles Or Less 500-875 More Than 1000 Miles 550-875 (1) Spec listed with Air Metering Fitting (6457) installed.
6. Shut engine off. If minimum airflow idle RPM is within specification, throttle body is okay. Go to step 9). If minimum airflow idle RPM is not within specification, go to next step.
7. Remove throttle body. Fully open throttle valve on throttle body. Using approved cleaner, clean throttle body bore, throttle valve and all passages. Use soft cleaning pad to clean throttle body bore and throttle valve. Ensure throttle valve-to-throttle body bore contact surfaces are clean so throttle valve will not be held open. Using compressed air, dry throttle body.
8. If correct minimum airflow idle RPM is now obtained, shut engine off. Go to next step. If correct minimum airflow idle RPM cannot be obtained, problem is not caused by throttle body. Go to next step.
9. Remove air metering fitting. Reinstall vacuum hoses as necessary. Remove scan tool.

THROTTLE POSITION SENSOR

Note. Throttle Position (TP) sensor is non-adjustable. Use the following procedure to check TP sensor calibration. For complete testing of TP sensor and wiring circuit, see the TESTS W/CODES - 2.4L article.

1. Remove components for access to electrical connector at TP sensor, mounted on throttle body. With electrical connector installed on TP sensor, turn ignition on with engine off. DO NOT start engine.
2. Using digital volt-ohmmeter, measure voltage at center terminal on electrical connector for TP sensor with throttle valve closed (idle position). Voltage should be within specification. See THROTTLE POSITION SENSOR VOLTAGE SPECIFICATIONS table.
3. Slowly open throttle to full throttle and note voltage reading. Voltage should smoothly increase to specification. See THROTTLE POSITION SENSOR VOLTAGE SPECIFICATIONS table. Replace TP sensor if voltage is not within specification.

THROTTLE POSITION SENSOR VOLTAGE SPECIFICATIONS (1)