2009 Jaguar XF supercharged V8. 100k miles.

Scanned a P0171 and P0174 code on two different trips. the engine is running lean, so i did some research to see how to go about fixing the problem.

It says monitoring the LT/ST fuel trims is a quick and highly effective way of doing it.

I have the torque hp pro apt for this. These are the readings after I did a check engine light reset and completed a 15 mile run.
8 miles of highway going 70 mph and the rest stop and go. Here, the pic shows the car at idle afterwards.
Here is the car at 2500 rpms, sitting still.
As soon as i release the gas pedal.
And at idle, 30 seconds after the 2500 rpm screen shot.
I must mention, the previous day while monitoring the ECU, no codes where present.

The following morning i checked the oil, added a small amount of coolant, then put fuel into the vehicle while engine was running. Then engine light came on some time later.

Since then, I tightened up the cap and reseated the dipstick. Still, the light is on. Any suggestions in the right direction is appreciated.

 

I would start checking for vacuum leaks...maybe EGR. Given the miles and age of your car, it could be possible that some of the rubber hoses have deteriorated to a degree they leak.

 

I think that you have some sort of an intake leak somewhere that is causing this situation.