I have a Jaguar XJ6 4.0 X300 on a 1997 plate. I recently changed the MAF sensor for a second hand one. The petrol consumption has improved slightly any ideas on what to try next ? I was thinking maybe plugs or check for faulty coil pack but maybe I'm wrong. Any ideas would be grateful.

 

Presumably fuel consumption has increased dramatically above normal?

This thread has a good list of possibilities from Grant Francis and xjrguy:

https://www.jaguarforums.com/forum/g...n-4-0-a-91579/

See posts #2 and #4.

Graham

 

What's your consumption?
It may be normal..
My 3.2 will do 20 mpg average but if I drive like a nana I can get 25. If I floor it, I get 17mpg.
My XJR is surprisingly similar. I average 18-19 mpg which includes heavy foot, up to 100 mph quite often. I can get 25 on a long run if I drive to the speed limits

This is all Imperial gallons, 4.5 litres.

 

My 4.o litre Sovereign is showing 20.9 mpg. This covers three years of ownership with a lot of short, city runs (to and from the local golf club)

 

It shows around 14 to 15 mpg around town. Not 100% sure on a run like motorway etc. It seems weird this is the second 4.0 X300 I have had with the same petrol consumption problems. On my other one I never managed to sort the problem out. It used to do about 200 miles to a full tank of fuel which is the same as my current one. What do people get on average to a full tank on there X300 ?.

 

I get 16 when driving locally, lots of hills and stop signs/traffic signals. on the motorway it jumps to 24. That's US gallons with 89 octane. Maybe a little better with 91 octane, but not significant. I have the Andy bracket.

 

I took my car to the garage and had it put on the diagnostic computer. I have enclosed a snapshot of the errors it showed up they was all reset and the only two errors that came back was the 2 egr valve ones. This would explain the petrol smell outside the car. Does this mean its best to get a new EGR valve and get it fitted ?. Also does anyone think the 02 sensor may be causing the petrol consumption problem also ?. The error code did not return after clearing the codes but that does not mean it wont come back again after driving the car a while. Any suggestions are welcome and is it a garage job to get it fitted ?.

 

Im not sure that UK cars have EGR fitted, but worth checking. At a tangent to that line of thought, have you checked the fuel supply and return pipes from the tank? They are known to rust, and eventually need replaced. A pinhole leak would account for the smell of petrol and poor consumption. Just a thought.