I'm running an XF 2.2 Diesel Luxury 200 and at the weekend went out for a drive round the Yorkshire Dales taking in some excellent driving roads, however about 20 miles into the drive the power kept dropping generally at left hand turns and the throttle became unresponsive and to regain power I had to lift off throttle completely then re-apply and power was restored.
This was annoying but non-the-less not a major problem till several miles later came to a long hill when the power fell off again and the car decellarated. I had to release the throttle then re-apply and this happened about 3 times over the course of a hill about half Km. The car them performed OK following this until I reached a steep, long hill not far from home and this loss of power re-occurred but this time was about every 50 yds and I was in doubt that the car would reach the top. Fortunately on both uphill occasions there were no vehicles behind otherwise the car would be in the bodyshop for rear end repairs.
With the power loss the throttle was totally unresponsive but when released and reapplied the revs went to 3,000 / 3500 revs and picked up.
The car is now in for its first service at 11,500 miles 2 days after this iincident and following up with the dealer they have said there is no fault - I have told them to look again.
Anyone had any similar problems - at a rough guess I would say this is likely to be a problem with a sticking or faulty turbo ?

 

Possibly fuel pump? With modern cars the electronics seem to run everything, so I suppose it could also be in the electronic area.

Hopefully the dealer will drive the car for a bit and try to re-create the issue.

One other area on Jaguars (or at least on some models), they have a split fuel tank as a connection between the two tanks is used to ensure both sides of the tank are used. Apparently, if the connection hose is twisted, and the fuel has dropped down to say below half way, the engine could starve a bit for fuel. The way to test this is to fill the car and if the problem goes away, then this could be it.... and in turn the problem surfaces again after the tank level is down.

I had a XJR a few years ago that had this exact problem, and once diagnosed, the issue was easy to solve. In my case the engine just died at the point of low fuel as the twisted connection was really severe.

Lawrence.

 

Thanks Lawrence,
Not sure about the split tank as the fuel was more than 3/4 full, maybe Fuel Pump but responded when the throttle was released then applied so not sure about that.
Have asked the dealer to fully check it out but the problem is that it is very intermittent and at the weekend occurred after driving over 50 miles.

 

The Dealer has finally found the problem after a full day of road testing and several frustrating phone calls.


On the braking system is a sensor which detects when Brakes are applied and this then tells the accelerating circuit to drop revs to idle. The sensor was faulty and this was activating when doing a left turn and during uphill climbs.


Sensor now replaced and hopefully will start to really enjoy "The Jag "

 

I also have this exact same problem what brake sensor was changed?