VALVE CLEARANCE
Note. All engines use hydraulic lifters. No adjustments are required.
IGNITION TIMING
Note. Always refer to Emission Control Label in engine compartment before attempting service. If manual and label differ, always use emission label specifications. Timing is controlled by Powertrain Control Module (PCM) on 5.2L engines, and is not adjustable.
| CAUTION | DO NOT puncture cables, boots or nipples with test probes. |
| Application | (1) Degrees BTDC |
|---|
| 5.2L | (2) |
| (1) At idle. (2) Ignition timing is controlled by PCM and is not adjustable. |
| (2) | Ignition timing is controlled by PCM and is not adjustable. |
THROTTLE BODY MINIMUM AIRFLOW
- Set parking brake and block front wheels. Warm engine in Park or Neutral until cooling fan cycles on and off at least once. Ensure all accessories are off. Remove air cleaner assembly and disconnect PCV hose from PCV valve. Attach 0.185" Fixed Orifice Air Metering Fitting (6714) into disconnected vacuum line in place of PCV valve.
- Disconnect idle purge vacuum hose from front of throttle body next to MAP sensor. Cap throttle body vacuum fitting. Connect DRB to DLC. Start engine and allow to idle for at least one minute. Using DRB, access MINIMUM AIRFLOW. When accessed, DRB will count down to stabilize idle RPM and display minimum airflow idle RPM. See THROTTLE BODY MINIMUM AIRFLOW IDLE SPECIFICATIONS table.
- If throttle body minimum airflow idle speed is not within specification, check for vacuum leaks. If there are no vacuum leaks, replace throttle body.
| Application | RPM |
|---|
| 5.2L | 500-900 |
THROTTLE BODY MINIMUM AIRFLOW IDLE SPECIFICATIONS
THROTTLE POSITION SENSOR (TPS)
Note. Throttle Position Sensor (TPS) is not adjustable. Following procedures may be used to check TPS calibration. For complete testing of TPS, see the article TESTS W/CODES - 5.2L in the ENGINE PERFORMANCE section.
- Remove air cleaner housing assembly. Turn ignition switch to ON position. DO NOT start engine. Using a DVOM, measure voltage at center terminal of TPS, with throttle valve in idle position fully closed against stop. Voltage should be within specification. See THROTTLE POSITION SENSOR VOLTAGE TEST table. If voltage is not within specification, replace TPS.
- Slowly open throttle valve to Wide Open Throttle (WOT). TPS voltage should increase steadily to specification. If voltage does not increase steadily to specification, replace TPS.
| Throttle Opening (2) | Volts |
|---|
| Idle | Greater Than 0.2 |
| WOT | Less Than 4.8 |
| (1) Voltage should increase steadily as throttle opening is increased from idle position. (2) Measure voltage at throttle position sensor center terminal. |
| (1) | Voltage should increase steadily as throttle opening is increased from idle position. |
| (2) | Measure voltage at throttle position sensor center terminal. |
THROTTLE POSITION SENSOR VOLTAGE TEST (1)
