Engine Adjustments - 5.9l Dodge Ram II

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). Ignition timing is non-adjustable. DO NOT attempt to adjust ignition timing by rotating distributor.

If distributor is rotated, fuel system synchronization will be changed. If distributor is removed or rotated, check fuel system synchronization. See FUEL SYSTEM SYNCHRONIZATION under FUEL SYSTEM.

FUEL SYSTEM SYNCHRONIZATION

Note. Fuel system synchronization is controlled by position of the distributor. Rotating of distributor WILL NOT change ignition timing, but will change fuel system synchronization. Fuel system synchronization should be checked any time distributor is removed or rotated.

Scheme 3

1. Connect scan tool to Data Link Connector (DLC). DLC is located below driver's side of instrument panel, to the left of steering column. (Scheme 3) (Scheme 3): Data Link Connector Location
2. Using scan tool manufacturer's instructions, access SET SYNC display on scan tool. Following scan tool displays, start engine. With engine running, if scan tool displays IN RANGE along with 0°, this indicates correct distributor location. The degree reading displayed on scan tool indicates the fuel synchronization, not ignition timing.
3. If scan tool display is correct, shut engine off. Remove scan tool. If scan tool does not display IN RANGE along with 0°, go to next step.
4. If scan tool displays a plus (+) or minus (-) sign next to the degree number, and/or the degree number displayed is not zero, loosen but DO NOT remove distributor hold-down bolt.
5. Rotate distributor until scan tool displays IN RANGE. Continue to rotate distributor until a reading as close as possible to 0° is obtained. Tighten distributor hold-down bolt to 16 ft. lbs. (22 N.m).

IDLE SPEED & MIXTURE

Idle speed/mixture controlled by Powertrain Control Module (PCM). No adjustment is required. The PCM controls Idle Air Control (IAC) motor for proper idle speed. See TESTS W/CODES - 5.9L 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.

1. Start and warm engine to normal operating temperature. Ensure all accessories are off. Shut engine off. Remove air cleaner.
2. Disconnect vacuum line at PCV valve, located in valve cover. Install.185" fixed orifice Air Metering Fitting (6714) into disconnected vacuum line in place of PCV valve.
3. Disconnect purge vacuum hose from passenger's side front corner of throttle body, next to MAP sensor.
4. Connect scan tool to Data Link Connector (DLC). DLC is located below driver's side of instrument panel, to the left of steering column. (Scheme 3)
5. Start and warm engine to normal operating temperature. Using scan tool manufacturer's instructions, access MINIMUM AIRFLOW display on scan tool. When accessed, scan tool will count down to stabilize idle RPM and display minimum airflow idle RPM. Minimum airflow idle RPM should be 500-900 RPM.
6. Shut engine off. If minimum airflow idle RPM is correct, throttle body is okay. Go to next step. If minimum airflow idle RPM is not within specification, using approved cleaner, clean throttle body and recheck minimum airflow idle RPM. If correct minimum airflow idle RPM cannot be obtained, replace throttle body. Go to next step.
7. Remove air metering fitting. Reinstall vacuum hoses as necessary. Reinstall air cleaner. Remove scan tool.

THROTTLE POSITION SENSOR

Note. Throttle Position (TP) sensor is nonadjustable. Use following procedure to check TP sensor calibration. For complete testing of TP sensor and wiring circuit, see the TESTS W/CODES - 5.9L 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)

See also:
• TESTS W/CODES - 5.9L