1. Smoke Test: This is the most effective way to pinpoint an EVAP leak. A qualified mechanic uses a machine that introduces smoke into the EVAP system. Leaks will show up as escaping smoke. This quickly identifies the source of the problem – a cracked hose, loose connection, a faulty canister, or a leak in the fuel tank itself.
2. Inspect the EVAP System Components: Even if you replaced the purge valve, carefully inspect:
* All hoses and lines: Look for cracks, kinks, loose connections, or areas where rodents may have chewed on them. Pay close attention to the areas where the hoses connect to the canister, fuel tank, and purge valve. Replace any damaged hoses.
* EVAP canister: This is a charcoal canister that stores fuel vapors. Inspect it for cracks or damage. Sometimes the canister vent valve can fail.
* Fuel tank: Look for any signs of damage or rust around the fuel filler neck or the area where the EVAP lines connect.
* Gas cap: While you replaced it, ensure it's correctly tightened and the seal is good. A faulty gas cap is a common cause of P1443, even if you've replaced it, so double-check.
* Purge valve solenoid wiring: Ensure the wiring to the purge valve (solenoid) is securely connected and not damaged.
3. Pressure Test: A pressure test involves pressurizing the EVAP system and monitoring for pressure loss. This directly identifies leaks that a visual inspection might miss. This is usually done with a specialized EVAP system tester.
4. Check for Vacuum Leaks: While less likely to directly cause this code, a major vacuum leak elsewhere in the engine can sometimes affect the EVAP system's ability to operate correctly.
Why the intermittent issue?
The intermittent nature strongly suggests a leak that's affected by temperature changes, pressure variations, or movement of the vehicle. Heat cycling can cause minor cracks to open and close, for example.
Professional Help:
If you're not comfortable inspecting and repairing the EVAP system yourself, take your Cougar to a qualified mechanic. A smoke test and pressure test are best performed by someone with the necessary equipment and expertise. Attempting repairs without proper tools and knowledge can lead to further damage or incorrect diagnosis.
In summary, while replacing common parts is a good starting point, a thorough inspection and testing of the entire EVAP system are essential to resolving the P1443 code permanently. The smoke test is your best bet for a quick and accurate diagnosis.
