If your 1998 Chrysler Cirrus has an idle speed problem (too high, too low, erratic), the issue isn't a simple adjustment. Instead, you need to diagnose the underlying cause. Possible culprits include:
* Dirty or faulty throttle position sensor (TPS): This sensor tells the PCM where the throttle is. A dirty or faulty sensor will lead to inaccurate readings and incorrect idle control. Cleaning it (with appropriate cleaner) or replacing it might solve the problem.
* Faulty idle air control (IAC) valve: This valve regulates the amount of air entering the engine at idle. A malfunctioning IAC valve can cause erratic or incorrect idle speeds. Cleaning it (with appropriate cleaner) or replacement might be necessary.
* Vacuum leaks: Leaks in the intake manifold or vacuum lines can disrupt the air/fuel mixture and affect idle speed. A thorough inspection is needed to identify and repair any leaks.
* Mass airflow sensor (MAF) problems: A dirty or faulty MAF sensor provides inaccurate air flow readings to the PCM, affecting the fuel mixture and idle. Cleaning or replacing it is a possible solution.
* Faulty PCM: While less common, a failing PCM can cause a variety of problems, including incorrect idle speed. This is usually the last thing to suspect and requires professional diagnosis.
* Other engine issues: Problems like worn spark plugs, dirty air filter, or other engine problems can indirectly affect the idle.
What you SHOULD do:
1. Check for diagnostic trouble codes (DTCs): Use an OBD-II scanner to read any trouble codes stored in the PCM. These codes can point you towards the source of the problem. Auto parts stores often offer free code reading services.
2. Visually inspect the components: Look for obvious signs of damage, loose connections, or vacuum leaks.
3. Clean the throttle body and IAC valve: This is a relatively simple procedure that can often resolve idle issues. Use a throttle body cleaner specifically designed for this purpose. Disconnect the battery negative terminal before doing this.
4. Consult a repair manual: A repair manual specific to your 1998 Chrysler Cirrus will provide detailed information on diagnosing and repairing idle speed problems.
5. Seek professional help: If you're not comfortable working on your car's engine, take it to a qualified mechanic for diagnosis and repair. Trying to adjust something you don't understand can cause further damage.
Simply trying to "adjust" the idle speed without addressing the root cause will likely be futile and could lead to more expensive repairs later. Focus on proper diagnosis first.
