Originally Posted by ala_xfire

What both previous posters are overlooking here is that the key and the starter are not connected on our cars.
The key just tells the PTCM that you want to start the car.
The PTCM then checks a whole slew of things to make sure all the ducks are in a row, then tells the pulse module it is OK to engage the starter motor.
The pulse module is designed to engage the starter for sufficient time to cause at least 2 complete revolutions of the engine.
The PTCM monitors this via the CPS sensor, once it sees that the TDC indication has occurred twice, it then knows the position of the crankshaft and can make timing decisions. ( at this point, the PTCM also employs signals from the Camshaft Position Sensor to fine tune the timing )
Only at this point does it energize solenoids in the RCM to provide fuel and power for the ignition coils, and Houston, we have lift-off !

BTW: on the XF, you only have to bump the key to start position for a few milliseconds for all the above to occur. You don't need to hold it there until the engine is started.

and : the gas pedal is only a mechanism that moves a variable resistor that tells the PTCM what you would like the engine to do. ( actually, I think this is a PWM signal ( Pulse Width Modulation ))
It makes the decisions from there and controls the stepping motor in the throttle body to speed up / slow down the engine.
True "fly-by-wire" engineering.

Originally Posted by Keepmeinmind13

Thank you all for the responses. It was a fuel sensor control. The dealer sent someone out and replaced it and now the car is running fine.