Oxygen sensors do not cause misfires. A misfire is a result of air, fuel, spark, compression, or timing. If you are getting the same fault codes after replacing the oxygen sensors, it suggests they were just reporting the condition, not causing it. Timing will not cause a problem on just one cylinder.
A spark-related misfire will send unburned fuel and air into the exhaust system. You will smell the fuel at the tailpipe, but the oxygen sensor only detects oxygen, so it will report a constant "lean" condition. Normal operation is it switches between "rich" and "lean" about two times per second. Staying lean too long will trigger a lean code or a slow response code. You can also get a lean condition from low fuel pressure, a plugged injector, or a vacuum leak.
You might want to switch two injectors, erase the fault codes, then see if a misfire code sets for a different cylinder. Chrysler has very little trouble with their injectors, but you do not want to overlook this possibility. This also might be a good time to do a compression test. If you find the suspect cylinder is low, look for a hole in the piston, (based on your description of rough running), or a damaged lobe on the camshaft.
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Thursday, December 29th, 2016 AT 12:51 PM
