* IAC (Idle Air Control) Valve: This valve regulates air flow at idle. A dirty or faulty IAC valve is a common cause of rough idling and stalling, especially when the engine is under low load (like at a stop). Cleaning it (with throttle body cleaner) is a relatively simple and inexpensive first step. If cleaning doesn't work, replacement is needed.
* MAF (Mass Air Flow) Sensor: This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor will provide inaccurate readings, leading to a rich fuel mixture (hence the smell) and rough running. Try cleaning it with MAF sensor cleaner (specific cleaner is crucial; don't use anything else). If cleaning doesn't help, replacement is likely needed.
* TPS (Throttle Position Sensor): This sensor tells the computer the throttle's position. A faulty TPS can cause erratic idle and stalling.
* Fuel Injectors: Clogged or leaking injectors can cause a rich mixture and poor idle. This is more involved to diagnose and often requires professional testing or replacement.
* Vacuum Leaks: Leaks in vacuum lines can disrupt the air/fuel mixture, causing rough idling and stalling. Inspect all vacuum lines for cracks or disconnections.
* PCV (Positive Crankcase Ventilation) Valve: A faulty PCV valve can cause excessive crankcase pressure which can affect the air/fuel mixture.
* O2 (Oxygen) Sensor: While less likely to directly cause stalling at idle, a faulty O2 sensor prevents the computer from accurately adjusting the air/fuel mixture. This contributes to the "running rich" condition and the check engine light.
Troubleshooting Steps:
1. Check the Engine Codes: Use an OBD-II code reader to retrieve the diagnostic trouble codes (DTCs) stored by the computer. These codes will give you a much better idea of the specific problem.
2. Clean the IAC Valve and MAF Sensor: These are easy, relatively inexpensive things to try first. Follow instructions carefully when using cleaning sprays.
3. Inspect Vacuum Lines: Look for any cracks, loose connections, or damaged hoses in the vacuum system.
4. Check the PCV Valve: This is a relatively easy part to access and replace if necessary.
5. Professional Diagnosis: If you haven't solved the issue after these steps, take your Astro to a qualified mechanic. They have tools and expertise to diagnose more complex problems like fuel injector issues, or other sensor failures.
The rich smell and check engine light point towards a fuel-related issue, but the stalling suggests a problem that affects the idle specifically. The combination suggests multiple issues could be at play, making professional diagnosis advisable if the initial steps don't yield a solution.
