Im having two problems currently. I am misfiring on cylinder 2 but with no fault code. The only fault code i'm throwing is p0172 for rich. Would the misfire be causing the rich? Are they independent? and how might I fix these two problems? Thanks for any help, Sorry if someone has already made this thread but I wanted it particular to my case.

'05 Supercharged

 

DTC P0172

CIRCUIT DESCRIPTION
The powertrain control module (PCM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. Fuel delivery is controlled differently during Open Loop and Closed Loop. During Open Loop, the PCM determines fuel delivery based on sensor signals, without heated oxygen sensor (HO2S) input. During Closed Loop, the PCM adds HO2S inputs and level of purge to calculate the short and long term fuel trim adjustments. If the HO2S indicates a lean condition, the fuel trim values will be above 0 percent . If the HO2S indicates a rich condition, the fuel trim values will be below 0 percent . The short term fuel trim values change rapidly in response to the HO2S voltage signals. The long term fuel trim makes coarse adjustments in order to maintain Air/Fuel Ratio of 14.7:1. The fuel trim diagnostic will conduct a test to determine if a rich failure actually exists or if excessive vapor from the evaporative emission (EVAP) canister is causing a rich condition. A block of cells contain information arranged in combinations of engine RPM and engine load for a full range of vehicle operating conditions. The long term fuel trim diagnostic is based on an average of cells currently being used. The PCM selects the cells based on the engine speed and load. If the PCM detects an excessively rich condition, DTC P0172 sets.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0172 Fuel Trim System Rich

CONDITIONS FOR RUNNING THE DTC
DTCs P0030, P0036, P0068, P0069, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0201-P0204, P0220, P0222, P0223, P0300, P0301-P0304, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P0506, P0507, P1133, P1134, P1516, P2101, P2119, P2120, P2125, P2135, P2138, P2176 are not set.
The engine is in Closed Loop status.
The engine coolant temperature (ECT) is between -7 and +120°C (+19.4 and +248°F) .
The intake air temperature (IAT) is between -7 and +145°C (+19.4 and +293°F) .
The manifold absolute pressure (MAP) is between 15-100 kPa (2.2-14.5 psi) .
The mass air flow (MAF) is between 1-512 g/s .
The vehicle speed is less than 132 km/h (82 mph) .
The engine speed is between 400-6,100 RPM .
The barometric pressure (BARO) is greater than 74 kPa (10.7 psi) .
The fuel level is more than 10 percent .
DTC P0172 runs continuously when the above conditions have been met.
CONDITIONS FOR SETTING THE DTC
The long term fuel trim weighted average value is less than a calibrated value.
The above condition is present for more than 2 minutes .

One cylinder misfiring can dump raw fuel into the exhaust and the o2 readings can be rich.