If your 2002 Dodge Neon is idling too high or too low, the problem likely lies elsewhere and requires diagnostics, not an idle adjustment. Here's a breakdown of how to troubleshoot:
1. Check for Diagnostic Trouble Codes (DTCs):
* OBD-II Scanner: The most important first step. Use an OBD-II scanner (available cheaply at auto parts stores) to read any trouble codes stored in the PCM. These codes will point to the likely cause of the idle problem. Common culprits include:
* IAC (Idle Air Control) Valve Issues: A dirty or malfunctioning IAC valve is a very common reason for idle problems.
* MAP (Manifold Absolute Pressure) Sensor Problems: This sensor tells the PCM how much air is entering the engine. A faulty sensor leads to incorrect fuel mixture and idle issues.
* TPS (Throttle Position Sensor) Problems: A faulty TPS sensor gives the PCM inaccurate information about the throttle position, affecting idle.
* Mass Airflow Sensor (MAF) Problems: Similar to the MAP sensor, a faulty MAF sensor will provide inaccurate information to the PCM.
* Vacuum Leaks: Leaks in the vacuum system can cause erratic idle.
2. Address any DTCs:
Once you have the codes, research them online (many resources are available) to understand the likely cause. This will often guide you towards the specific part to replace or clean.
3. Check for obvious mechanical problems:
* Vacuum Leaks: Inspect all vacuum hoses and connections for cracks or leaks.
* Clean the IAC Valve: If the DTC points to the IAC valve, you might try cleaning it with a throttle body cleaner (following instructions carefully). Often this solves the problem. However, a severely faulty IAC valve usually requires replacement.
4. Professional help:
If you're uncomfortable diagnosing or repairing the problem yourself, take your car to a qualified mechanic. They have the tools and experience to properly diagnose and fix the issue. Attempting to adjust something you don't understand in the engine management system can cause further damage.
In short: There's no "idle adjustment screw" on a 2002 Dodge Neon. Focus on diagnosing the underlying cause using an OBD-II scanner and addressing any found problems.
