If your Sebring's idle speed is too high or too low, the problem is almost certainly *not* a simple idle speed adjustment. Instead, it points to an underlying issue that needs diagnosis. Here are the most common causes and how to address them:
* Dirty or Faulty Idle Air Control (IAC) Valve: This valve controls the amount of air entering the engine at idle. A dirty IAC valve can cause erratic idle, while a faulty one can lead to stalling or high idle. Cleaning the IAC valve (with appropriate cleaner, following instructions online for your specific engine) is often a first step. If cleaning doesn't help, replacement is necessary.
* Vacuum Leaks: Leaks in the intake manifold vacuum system can cause erratic idle. Inspect all vacuum hoses for cracks, splits, or loose connections. Pay close attention to the PCV valve and hoses.
* Faulty Throttle Position Sensor (TPS): The TPS tells the PCM the throttle's position. A bad TPS can lead to a variety of issues, including improper idle.
* Mass Airflow Sensor (MAF) Problems: The MAF sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor will throw off the fuel mixture, affecting the idle. Cleaning the MAF sensor (carefully, with MAF sensor cleaner) might resolve the issue, otherwise it may need replacement.
* Faulty PCM: While less common, a malfunctioning PCM can also cause idle problems. This is a more expensive and complex issue to diagnose and repair.
* Other Sensors: Other sensors, such as the coolant temperature sensor or oxygen sensors, can also indirectly affect idle speed.
What to do:
1. Check for trouble codes: Use an OBD-II scanner to retrieve any diagnostic trouble codes (DTCs) stored in the PCM. These codes will often pinpoint the problem. Auto parts stores usually offer free code reading services.
2. Inspect vacuum lines: Carefully examine all vacuum lines for leaks or damage.
3. Clean the IAC valve: This is a relatively easy and inexpensive first step.
4. Clean the MAF sensor: Do this carefully, following the instructions on the MAF cleaner.
5. Consult a Repair Manual: A repair manual specific to your 1999 Chrysler Sebring will provide detailed information about your engine's idle control system and troubleshooting procedures.
6. Take it to a mechanic: If you're not comfortable diagnosing and repairing these issues yourself, it's best to take your Sebring to a qualified mechanic. Attempting to adjust the idle speed without understanding the underlying problem will likely make things worse.
In short, don't try to "set" the idle speed directly. Fix the underlying cause instead.
