Hi guys
I have a 2002 jaguar x type 2.5 sedan
Recently the digital display on the dash which shows the approx km’s left based on my gas has been playing up.
For example if I put in $40NZD which would get the display to say around 200km.. after driving about 2km it will go to 192 and so on… I haven’t ran it to empty yet to see what happens but some thing is clearly wrong as for the past two years I have owned the car the display has run very precisely.
Does any one have any experience or suggestions to what this could be?
Getting it checked out at the dealer here in NZ would cost me a arm and a leg and they would probably lie to me any way…
When I leave the car over night the approx distance left will remain the same the next day so it only looses km’s while driving..
Does this sound like the computer just needs to be reset or what else could it possibly be?
Any feed back greatly appreciated!

 

Luka, please keep in mind that the KM's left to empty is a calculated value based on the average mileage over the last little bit of driving (not over the whole tripometer recording). So, you will see the "miles left" go up and down slightly based on stops, starts, and long runs.

A prime example is what I experience all the time in that I will have say 40 miles left and know that it is 13 miles each way to work from home. After making 3 of these trips, I will still have say 10 miles left. Obviously there is a issue here, but it is all in how I am driving at the various points. I would say to call it good and just keep an eye on things. Keep a closer eye on the gas gauge than the miles left. I've had a car or two that told me that I had miles left but the motor turned off due to lack of fuel. Granted, the gas gauge had been yelling at me to add more fuel.

 

Cheers Thermo
I don’t understand cars to well especially all the electrics on the newer ones but judging by your response it doesn’t sound like my issue could be something very major?
I understand your logic about it being calculated on the average mileage over the last bit of driving but I have always kept an eye on it and something is definitely playing up. Until now it served me well and went down in consistent amounts but now I find myself at a traffic light with say 190 and while I am parked it flicks down to 184 and is pretty much going down twice as fast during the same type of driving which I have previously been doing for the past 2 years in it…
Im wondering if there is a sensor or something that could be dusty or damaged which is causing this recent unpredictable activity?

 

Luka, it is possible that you are getting some build up inside of the engine or you have a very minor vacuum leak, or something else of that nature. What I would tell you to do is to first start with the easy stuff. If you haven't in the last 5000km run a bottle of injector cleaner through the car, do that. Cheap thing to do and in a lot of cases, helps remove the minor things. Also, look at the vacuum lines in the car. There's 3 spots you want to especially look at as they are the common problems with the cars:

-vacuum line running from the top of the intake to the brake booster (develops a crack near the bulb in the center- this bulb is a check valve)
-the 20mm vacuum line running from the intake to the intake cover nearest the radiator (develops a crack in the top of the hose, should be ribbed. But if smooth, you have the old style hose and should be monitored as these have a semi-high failure rate, $15 USD part)
-Intake tuning valve o-rings. These are located on the left side of the engine if you are looking into the engine bay with your feet at the bumper. These are the 75mm black circles on the side of the intake. The o-rings are prone to failure, much like the 20mm vacuum line. $3 USD each part, 2 required.

After that, do the "idiot" checks. Make sure the air cleaner is not plugged, fuel filter been changed in the last 25,000KM, stuff like that. Most of this is simply doing a little inspection by yourself, not costing you any money overall.

 

Thanks again Thermo! Highly likely it will be a case of an ‘idiot check’.. il try your suggestions and let you know how I got on!
Cheers

 

I'm certainly not one of the most technically savvy members on here, but I'm going to throw something out. Did you recently reset your trip computer after not having done that in a long time? If so, my thinking is is if the formula that goes into the distance to empty calculation has a small sample size, in this case satrting again from zero, you will see some odd fluctuations on the reading because your average speed might be all over the board. If you had a lot of miles logged in the trip computer then the sample size that goes into that calculation is so high that it wouldn't vary much anymore. Hope that makes sense. Like I said, I don't know how that calculation is figured, I just thought I would throw that out there as you didn't say that your actual mileage had changed or the performance has recently gotten worse or you have any lights showing on the dash.

 

One of the things that can cause alarm on the range reading after filling up is if you reset the readings, and then continue to fiddle in the car while the engine is running.

This activity is quite reasonable on a fuel stop, but it has the effect of lowering your range reading because the computer sees X amount of fuel to move only Y distance. It has a large effect if there is little data for the computer to work with. It will normalise quickly once you have overcome the consumption from idling.