Poor Fuel Mix Wreaks Havoc on Stratus Performance

I had a similar issue with my 2003 Dodge Neon last year (some experience with car repairs). The symptoms match exactly what you described, rough running, stalling at idle, and power loss. The fuel injection system was the culprit. After diagnostic testing, the workshop found a defective injector that was causing irregular fuel spray patterns. This threw off the entire fuel mixture and affected engine performance. The throttle body was also checked but was functioning properly. The repair involved: Complete fuel system diagnosis, Cleaning the intake manifold, Replacing one faulty fuel injector, Testing all spark plugs, Verifying catalytic converter function Total repair cost was 515€ including parts and labor. The car has run perfectly since then with no check engine light or performance issues. Before suggesting specific fixes, could you share: Current mileage? Any recent maintenance done? Does the problem get worse when the engine is hot or cold? Have you noticed any unusual fuel consumption? Any specific error codes from the check engine light? This information would help determine if your issue is identical to what I experienced with the injector.

Had my last service at 23103KM. The mass airflow sensor was cleaned during that service but the rich mixture problem persists. When they checked the error codes, P0172 came up indicating a rich fuel mixture. I tested fuel consumption before and after cleaning, no improvement. The check engine light is still on despite the cleaning. Think I should look into the catalytic converter next? The workshop suggested this but wanted a second opinion since its an expensive fix. The car runs slightly better when cold but gets notably worse once warmed up. Fuel economy is terrible now, using about 25% more fuel than normal.

Interesting that the MAF sensor cleaning didnt resolve your rich mixture condition. Based on my experience with the same issue on my Stratus, the P0172 code combined with worse performance when warm points strongly to a faulty oxygen sensor. When my O2 sensor started failing, it caused similar symptoms by incorrectly reporting the air-fuel ratio to the ECU. This made the system continuously adjust to an overly rich mixture, especially at operating temperature. The catalytic converter was actually fine, though the rich condition could eventually damage it if left unchecked. The repair steps that fixed my car were: Testing the oxygen sensor voltage output, Confirming proper fuel pressure, Replacing the faulty O2 sensor, Clearing the check engine codes, Verifying proper air-fuel ratio after repair The complete fix cost 220€, much cheaper than a catalytic converter replacement. My fuel consumption returned to normal within a few tanks, and the check engine light has stayed off. Would suggest having the oxygen sensor tested before considering the catalytic converter. A bad O2 sensor can mimic catalytic converter symptoms, but costs significantly less to replace.

Thanks for that detailed advice about the oxygen sensor testing. I'll have the workshop check the O2 sensor output before moving forward with the catalytic converter replacement. You make a good point about the rich mixture symptoms getting worse when warm, that does line up with a failing oxygen sensor. The mass airflow sensor cleaning didn't help much, so exploring the O2 sensor route makes sense, especially since it's a much cheaper fix than the catalytic converter. I'll have them do the full diagnostic testing you suggested, particularly checking the sensor voltage output and fuel pressure. Really hoping this turns out to be just the oxygen sensor, 220€ sounds much better than what they quoted for a new catalytic converter. I'll update once I get the test results back and know if the air-fuel ratio improves after checking these components.