Understanding the Problem
The "EGR valve pintle position" code means the computer isn't receiving the correct signal about how open or closed the EGR valve is. Here's how it works:
* EGR Valve: This valve controls the amount of exhaust gas that is recirculated back into the engine. This helps reduce emissions and combustion temperature.
* Pintle: A small rod inside the EGR valve that controls the flow of exhaust gas.
* Sensor: A sensor in the EGR valve tells the computer the valve's position.
Possible Causes
1. Faulty EGR Valve: While you've replaced the EGR valve, it's possible the new one is faulty or is not compatible with your vehicle.
2. Vacuum Leak: A leak in the vacuum line leading to the EGR valve can prevent proper operation.
3. Clogged Vacuum Line: The vacuum line can become blocked with debris.
4. EGR Valve Position Sensor: The sensor itself might be defective, preventing accurate position readings.
5. Computer Issues: In rare cases, the engine control module (ECM) itself might have a problem, causing incorrect EGR valve commands.
Troubleshooting Steps
1. Verify New EGR Valve:
* Compatibility: Make absolutely sure the replacement EGR valve is the correct one for your 1995 Riviera.
* Function: Inspect the valve's pintle for free movement. It should slide smoothly with no sticking or binding.
2. Check Vacuum Lines:
* Visual Inspection: Thoroughly inspect all vacuum lines leading to the EGR valve for cracks, holes, or loose connections.
* Pressure Test: If you have a vacuum pump, test the vacuum lines for leaks. Apply vacuum and listen for hissing or see if the gauge drops.
3. Clean EGR Valve and Passageways:
* Cleaning: Even a new EGR valve can have debris in its internal passages. Remove the valve and clean it thoroughly with carb cleaner or a dedicated EGR cleaner.
* Passageways: The intake manifold where the EGR valve connects can also become clogged. Use a small brush or compressed air to clean out any debris.
4. Test EGR Valve Position Sensor:
* Resistance Check: You may need a multimeter to measure the sensor's resistance. Consult your vehicle's service manual for specific resistance values.
* Voltage Check: With the ignition on, test the voltage at the sensor's connector. Again, refer to your service manual for expected voltage readings.
5. Inspect Wiring Harness:
* Visual Inspection: Look for any frayed, broken, or corroded wires in the harness leading to the EGR valve.
* Continuity Check: Use a multimeter to check for continuity in the wiring harness.
6. Consider ECM Diagnosis:
* If all other possibilities are ruled out, it's possible the engine control module (ECM) is faulty and needs to be diagnosed and possibly replaced. This typically requires specialized tools and knowledge.
Important Notes
* Safety First: Always disconnect the battery before working on electrical components.
* Service Manual: A service manual specific to your 1995 Riviera will be incredibly helpful for diagnosis and repair.
* Professional Help: If you're unsure about any of these steps or if the problem persists, consult a qualified mechanic for further assistance.
