Engine Controls - Adjustments - 8.0l (r2500) Dodge Pickup R2500

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.

FUEL SYSTEM SYNCHRONIZATION

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

1. Connect scan tool to Data Link Connector (DLC). DLC is located below driver's side of instrument panel, near steering column. (Scheme 16)
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). Shut engine off. Remove scan tool.

Scheme 16

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 - 8.0L article for diagnosis of incorrect idle speed or IAC motor operation.

THROTTLE BODY MINIMUM AIRFLOW

Throttle body minimum airflow cannot be checked on this application.

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 - 8.0L 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 - 8.0L