Instead of directly adjusting the idle speed, you should focus on addressing underlying issues that might be causing an idle problem. Here's a systematic approach:
1. Check for Vacuum Leaks: Vacuum leaks are a common cause of erratic idle. Carefully inspect all vacuum lines and hoses for cracks, holes, or loose connections. Pay particular attention to the lines connected to the intake manifold, brake booster, and EGR valve. A spray bottle with carb cleaner or starting fluid can help locate leaks – spray around suspected areas while the engine is idling; a change in idle speed indicates a leak.
2. Throttle Body Cleaning: A dirty throttle body can affect idle. Remove the throttle body and clean it thoroughly with throttle body cleaner, paying attention to the IAC (Idle Air Control) motor and the throttle plate. Make sure to follow the cleaner's instructions and avoid getting cleaner on sensors.
3. IAC (Idle Air Control) Motor: The IAC motor is responsible for regulating idle speed. A dirty or malfunctioning IAC motor is a common culprit. Cleaning it (as part of the throttle body cleaning) might resolve the issue, but if cleaning doesn't help, it might need replacement.
4. Check for Engine Codes: Use an OBD-I scanner (you'll need one compatible with your vehicle's year) to retrieve any diagnostic trouble codes (DTCs). These codes can point to various issues affecting the idle, like a faulty sensor (MAP, TPS, etc.).
5. Mass Airflow Sensor (MAF) Sensor: A dirty or malfunctioning MAF sensor will also cause idle problems. Clean the MAF sensor carefully with MAF sensor cleaner (avoid touching the sensor element). Replacement might be necessary if cleaning doesn't help.
6. Throttle Position Sensor (TPS): A faulty TPS can send incorrect signals to the PCM, affecting idle. Testing the TPS is best done with a multimeter and referring to a service manual.
7. PCV Valve: A clogged PCV valve can cause vacuum issues and affect idle. Replace if necessary.
Important Considerations:
* Professional Help: If you're not comfortable tackling these steps yourself, take your Blazer to a qualified mechanic. Diagnosing idle problems can be complex, and incorrectly attempting repairs could worsen the issue.
* Service Manual: A service manual specific to your 1992 Chevy S10 Blazer is invaluable. It provides detailed diagrams, specifications, and troubleshooting procedures.
By systematically addressing potential problems, you'll be much more likely to solve your idle issue without resorting to potentially damaging adjustments to systems controlled by the computer. Remember, "adjusting the idle" on a fuel-injected vehicle like this involves fixing the underlying cause, not fiddling with a screw.
