ENGINE MECHANICAL
Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.
VALVE CLEARANCE
Note. All models use hydraulic lifters. Adjustments are not required.
IGNITION TIMING
Note. All models are equipped with nonadjustable timing systems.
IDLE SPEED & MIXTURE
Note. Idle mixture is controlled by Powertrain Control Module (PCM). Adjustment is not possible.
| CAUTION | When battery is disconnected, vehicle computer may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. Refer to the COMPUTER RELEARN PROCEDURES article in the GENERAL INFORMATION section before disconnecting battery. |
IDLE SPEED
Note. Idle speed is controlled by PCM and is not adjustable. Slight fluctuations in idle speed are considered normal. Start and run engine for at least 7 minutes to establish PCM control of idle.
Note. Incorrect idle speeds are normally caused by dirty throttle plate or vacuum leaks. Ensure all vacuum components are functioning properly.
IDLE MIXTURE
Note. Idle mixture is controlled by Powertrain Control Module (PCM). Adjustment is not required or possible.
THROTTLE POSITION SENSOR
Note. TP sensor is not adjustable. For further testing procedures, refer to the TESTS W/CODES article or the SYSTEM/COMPONENT TESTS article.
Note. Ensure accelerator and brake pedals are free from any obstructions while performing TP sensor learn procedure. PCM will not perform learn function with accelerator pedal or brake pedal obstructions.
TP Sensor Learn
If a NEW TP sensor, throttle body or PCM is installed, PCM must learn new TP sensor offset. This procedure is necessary because of manufacturing tolerances during minimum air adjustment, TP sensor being nonadjustable on throttle body and TP sensor manufacture. High idle at closed throttle or a stall condition may occur if PCM maintains an improper TP sensor offset. To perform TP sensor learn, turn ignition on leaving engine off. Wait 30 seconds, then turn ignition switch to LOCK position. Wait another 30 seconds.
| Application | (1) Volts |
|---|---|
| 4.6L | (2) (3) |
| (1) Voltage range is from idle position to wide open throttle position. (2) TP sensor is not adjustable. (3) Voltage range is less than one volt at closed throttle to greater than 4 volts at wide open throttle. | |
| (1) | Voltage range is from idle position to wide open throttle position. |
| (2) | TP sensor is not adjustable. |
| (3) | Voltage range is less than one volt at closed throttle to greater than 4 volts at wide open throttle. |
TP SENSOR ADJUSTMENT VOLTAGE
See also:
• TESTS W/CODES
• SYSTEM/COMPONENT TESTS