If the motor never warms to correct operating temp, it will stay in open loop and run extremely rich as it does in open loop, in closed loop the 02 sensors are added and so is EGR, 02 sensors are probably along with the MAF the most important fuel control sensors on the car. Low voltage does not allow the PCM to operate correctly! It is unusual for any of these sensors to be bad at 50,000 but not impossible. A thermostat or the ECT(engine coolant temp) sensor may be the place to start here. Does upper radiator hose get VERY hot? It should be cold until the tstat opens, then get hot. This should take 5-10 minutes. Testing a thermostat requires either a infrared thermometer aimed at the thermostat housing, or removal and suspend it in boiling water and a thermometer to see what temp it opens at.
Did the dealer test the fuel pressure and fuel pressure regulator? I also need the engine size in liters, 3.0 or 4.0?
Sunday, January 17th, 2010 AT 7:20 AM