Engine Controls - Adjustments Dodge Neon I

INTRODUCTION

Note. Introduction information not applicable.

ENGINE MECHANICAL

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

VALVE CLEARANCE

Note. Hydraulic lifters used. No adjustments are required.

IGNITION TIMING

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

IDLE SPEED

Manufacturer does not list procedure for checking idle speed. Idle speed is controlled by Powertrain Control Module (PCM). No adjustment is required. The PCM controls Idle Air Control (IAC) motor for proper idle speed. See the TESTS W/CODES article for diagnosis of incorrect IAC motor operation.

IDLE MIXTURE

Manufacturer does not list procedure for checking idle mixture. Idle mixture is controlled by Powertrain Control Module (PCM) and other electronic components. See the TESTS W/CODES article for diagnosis of incorrect IAC 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.

Scheme 1

Scheme 2

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. Install cap on PCV valve vacuum hose fitting on intake manifold. Disconnect idle purge hose from throttle body. (Scheme 1)
3. Using small piece of vacuum hose, install.125" fixed orifice Air Metering Fitting (6457) on idle purge hose fitting on throttle body. Connect scan tool to Data Link Connector (DLC), located below driver's side of instrument panel. (Scheme 2)
4. Start and warm engine to normal operating temperature until electric cooling fan cycles on and off at least once. Ensure all accessories are off. 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 the «THROTTLE BODY MINIMUM AIRFLOW IDLE»(/dodge/neon/i-1994-1999/remont/adjustments/#engine-controls-adjustments) SPEED SPECIFICATIONS table.
6. If minimum airflow idle RPM is within specification, throttle body is okay. Go to step 10). If minimum airflow idle RPM is not within specification, go to next step.
7. If minimum airflow idle RPM exceeds specification, using scan tool, check Idle Air Control (IAC) motor operation. If IAC motor operates correctly, replace throttle body. If IAC motor does not operate correctly, repair IAC motor as necessary.
8. If minimum airflow idle RPM is less than specified, clean throttle body. See «THROTTLE BODY CLEANING»(/dodge/neon/i-1994-1999/remont/adjustments/#engine-controls-adjustments__throttle-body-cleaning) under THROTTLE BODY. Recheck minimum airflow idle RPM.
9. If correct minimum airflow idle RPM is now obtained, shut engine off. Go to step 10). If correct minimum airflow idle RPM cannot be obtained, the problem is not being caused by the throttle body. Go to next step.
10. Remove air metering fitting. Reinstall vacuum hoses as necessary. Remove scan tool.

THROTTLE BODY MINIMUM AIRFLOW IDLE SPEED SPECS (1)

THROTTLE BODY CLEANING

1. 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.
2. 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.

THROTTLE POSITION SENSOR

Note. Throttle Position (TP) sensor is non-adjustable. Use following procedure to check TP sensor calibration. For complete testing of TP sensor and wiring circuit, refer to the appropriate TESTS W/CODES 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 (DVOM), 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 SPECS»(/dodge/neon/i-1994-1999/remont/adjustments/#engine-controls-adjustments) table.
3. Slowly open throttle to full throttle and note voltage reading. Voltage should smoothly increase to specification. See the «THROTTLE POSITION SENSOR VOLTAGE SPECS»(/dodge/neon/i-1994-1999/remont/adjustments/#engine-controls-adjustments) table. Replace TP sensor if voltage is not within specification.

THROTTLE POSITION SENSOR VOLTAGE SPECS

See also:
• THROTTLE BODY MINIMUM AIRFLOW IDLE
• THROTTLE BODY CLEANING