Could be a leaky injector/s and fuel pressure regulator-could be running to rich due to the following
Probable causes of an engine running rich are as follows:
1. Excessive fuel pressure can be cause by restricted fuel return line
2. Defective Oxygen Sensors.
4. Coolant temperature sensor out of calibration.
5. Restricted air intake system.
Saturday, September 3rd, 2011 AT 11:32 PM