A rough idle on this car is usually caused by one or more of these issues:
* IAC Motor: This is the most common culprit. A dirty or failing IAC motor can cause rough idling. Cleaning it (carefully) might help, but it often needs replacement.
* Mass Airflow Sensor (MAF) Sensor: A dirty or faulty MAF sensor provides inaccurate air readings to the PCM, leading to a poor idle. Cleaning it (with MAF sensor cleaner only!) is a good first step.
* Throttle Body: A dirty throttle body can restrict airflow. Cleaning it is important.
* Vacuum Leaks: Leaks in vacuum hoses can disrupt the engine's idle control. Inspect all hoses carefully.
* Spark Plugs and Wires: Worn spark plugs or faulty ignition wires can cause misfires and a rough idle.
* Fuel Injectors: Clogged or faulty fuel injectors can lead to an uneven fuel supply, causing rough idling.
* PCm Issues: In rare cases, a problem with the PCM itself can cause idle problems. This is harder to diagnose and usually requires professional help.
Instead of looking for an adjusting screw (which doesn't exist), you should focus on diagnosing these potential problems. Start with the easiest and most common:
1. Clean the MAF sensor: Use a specialized MAF sensor cleaner and follow the instructions carefully.
2. Clean the throttle body: Use throttle body cleaner and follow the instructions.
3. Inspect vacuum hoses: Look for cracks, splits, or loose connections.
4. Check spark plugs and wires: Inspect them for wear and tear. Consider replacing them if necessary.
If these steps don't resolve the issue, you'll likely need a professional mechanic to diagnose the problem more thoroughly. They have the tools and expertise to test the IAC motor, fuel injectors, and PCM. Ignoring a rough idle can lead to further engine damage.
