I was reading on my blackberry, and being lazy. Didnt read this:

"S-TYPE Instrument Cluster Self-Diagnostic ETM

To place the cluster in ETM, perform the following:

1.

2.

3. To navigate backward through the instrument cluster Self-Diagnostic Mode tests, press the trip computer ‘A/B’ button."


I'll go fiddle around with this.

 

Hey guys, I recently decided to run this test as well since I noticed the range was being listed as 45 miles but the gauge was around the middle of the red.

Here are the readouts:
Raw 1..........98
Raw 2..........36
Filter 1.........79
Filter 2.........0
Fuel %..........39
Fuel Driver.....58
range avg......45
fuel..............20.4mpg
gauge...........~5%?

So does this pretty much mean that one of the sensors is reading out incorrectly (broken?) since the filter 2 reads 0? I'll fill the car up a bit tomorrow and post the before and after again.

 

Put your car details in your profile

I don't think we know exactly what the readings are beyond what the TSB says.

However, if you rock your car the readings should fluctuate.

 

No that's about right. From the design of the tank, the one side empties faster than the other...

George

 

That's why I always keep a container of Spare Fuel in my car now.

My fuel gauge doesn't work properly like so many others.

Check it out.

http://www.sparefuel.net

 

I picked up my 03 STR in May and the fuel gauge always read slightly less than half a tank while it was full. When the low fuel light glows I'm humbled to know she has approx. 9 gallons in reserve, LOL!

 

For fuel gauge problems there is a TSB out. Take a look and see if it will help?
.
.
.

 

This has been very interesting reading... Thank you, all, for the insights.

I've driven my S-Type (03, 2.5 V6) a little less than 200 km (120 miles, I believe) since I last filled the tank but the fuel gauge is now almost exactly on 1/2 tank.

There's no way the engine will use that much fuel on that short distance, right? I'm assuming that there is a problem with the fuel gauge and will toy with the diagnostics tomorrow, after filling the tank and getting the real consumption numbers.

 

It should not have used 1/2 for that distance, but it COULD have. First, short journeys and/or a lot of stops (junctions, queues, etc) waste a lot of fuel. Second, if the car is not running "closed loop" it will run very rich. Or it can run very rich for other reasons. You might even have a slight fuel leak!

You'll need the true fuel usage over that distance to tell whether it's a bad gauge or bad fuel usage. If the latter, the next thing would be to use an OBD tool.

 

The latter worries me more because then I'd have to have it fixed asap. Would the OBD tool be able to show what's causing the bad fuel usage?

I guess I'll know more after filling the tank tomorrow. Thanks.

 

It should rule a lot of things either in or out. The tool needs to be able to read sensors (live data) as well as all the other common OBD settings and codes. Just a code reader will not reveal enough.
Something such as an elm327 is OK. Search will get you lots more about it.

 

Fuel consumption in cars has interested me since I started driving 45 years ago, mainly because of the high price of fuel in UK due to tax. For more than the last 30 years I've run diesels with odd exceptions.
I learned early on to ignore all sorts of claims (and opinions) about this, but to rely on my OWN checks, as scientifically as possible.
There's really only ONE way to check mpg: The full tank-full tank method, also called brim-brim method. Noting down the mileage at start, when next fill up to brim, note the new mileage. Subtract to get miles covered and divide this by the gallons pumped in. You then have a true mpg figure (true as it possibly can be depending on the mileometer accuracy and pump accuracy). This has highlighted some interesting facts:--
Computerized fuel consumption readouts are not that accurate, and used to be wildly INaccurate.
Dashboard fuel level meters/guages are also inaccurate, only to be taken as a guide, and often non-linear.
Fuel consumption is much worse during cold-engine running.
Diesels are consistently around TWICE as good as petrols, given like for like comparisons. If a diesel is not that much better, something is wrong, usually clogged injectors or some other malfunction.
Driving style, tyre inflation, rooftop air obstructions, stop-start driving all have an effect on fuel consumption.
Following all this, my S-type 2.7D., 121,000mile on the clock gets 32mpg. in big city driving, much more than the 'book' of 26mpg. For example, if a tyre is soft, this rises to 29mpg. This one alerted me that something was not quite right recently, and the best fault-finding technique is to go for the simple-easy things first, and yes, it was the third tyre I tested.
Finally, it's certainly not a good practice to allow your tank to get low. You might have a sudden emergency to handle in the middle of the night, (pregnancy, heart attack etc.) and you don't want your car to suddenly peter out halfway to the hospital.
If a diesel, although modern ones are self-priming, you don't really know what the air being sucked up in the fuel lines is going to do, what dirt and debris is going to be encouraged in both diesel and petrol. So don't do the 'Jeremy Clarkson' and risk it. It's just as easy to keep your tank full all the time.
Leedsman.

 

Here is another TSB on gauges that might help a bit??
.
.
.

 

OK... Filled the tank today. The gauge indicated a little less than 1/2, the trip computer that I'd driven 203km (120 miles), and I managed to put in 28 litres (7.4 gallon) of fuel. That would give around 14 litres/100km (a little less than 17 MPG).

To me, that indicates both that the gauge is off (around 10 litres too little?) and that the car (S-type 03, 2.5 V6) consumes more fuel than it should. I do need to collect more data, but I've not been very aggressive, nor have I spent most of the time in queues or on many short trips.

 

Like for like comparison, if my diesel S-type was a petrol, I would expect 15 to 18 mpg. This car weighs getting on for 2ton, and of course it doesn't feel heavy when U drive it (it's a Jag. after all) but nonetheless, there's a considerable weight of machinery for the engine to push. As I've been in this pickle myself over fuel consumption, I would urge -- do the routine stuff, blow up the tyres to spec., clean/replace bad spark plugs, clean/replace air cleaners, have someone look at the engine management system by checking the fault codes, I've heard about dodgy throttle bodies, check tyre wear for misaligned wheels. If you acquired the car recently you don't really know if it's been serviced properly and regularly, so it all needs checking. If you can get to one in your location, get an exhaust gas analyser plugged into your tail pipe and check carbon monoxide levels at tickover/idle with engine hot. The fig. should be less than 1.6%.It's boring, routine stuff, but good petrol fuel consumption is usually down to keeping things in good order. Best of luck!
Leedsman.
p.s. If it's any consolation, 17mpg. is what my friend's petrol BMW 528i did, and no matter how he drove it, it obstinately stuck at that fig.

 

Yes, I acquired the car recently, but it's been serviced by a reputable company here. That said, I will do what you suggest anyway - thanks.

I'm sort of miffed, though, because I bought that 2.5 because I figured it would save me some fuel when compared to a 4.2 or a 3.0. Seeing the figures now, it would seem that they are what a conservatively driven 4.2 might get.

 

Yes ineed Odeon, in the XJ6 days, you could have it with the 3.2ltre engine, or the more powerful 4.2. Those in the know always bought the larger because they knew there was no fuel consumption difference, but a lot more power. Why?
Examining engine statistics showed that the block and bore sizes were the same in both engines. More cc. was acquired by having a longer stroke and different crank throw, not by a bigger bore. It's a fundamental with i.c. engines that longer throw engines are more fuel-efficient with a like for like comparison. The penalty is a lower rev. limit. Also you can get away with valve timing (fixed in that case) skewed toward economy, because there's extra power to compensate. However, speaking generally over all cars, your guess is correct, usually a smaller engine results in better economy, excepting diesels. With diesels incidentally, a really effective turbocharging system results in a poorer mpg because the effective compression ratio and compression pressure rise away from the diesel ideal of around 18:1. This was noted in the indirect injection system, less fuel-efficient because you needed about 25:1 to get it to start, with some heater plugs under great stress. With many indirects, you had to sit there in winter for a whole minute heating the chambers before it was ready. The modern directs are easy to start.
If your 2.5litre petrol Jag. is tuned up and adjusted properly in every way, I should guess you might get better than 25mpg. on the highway/motorway at say a constant 60mph. If I got more than 30mpg. under those circumstances, I would think I was on a winner. Sort out the fine details and see how U go...
Leedsman.

 

It's generally reckoned the 4.2 NA is one of the best for mpg.

My STR is a 2004 and easy figures I have to hand are:
last 10 months, travelled 6141 miles, average mpg (by calculator) 23 (it's chance it's a round number but amused me)

If you get an OBD tool you really need to check the fuel trims but first must check it's running CL (closed loop) because if it's not then it is for certain running rich. You would NOT expect any codes (sadly) because the car literally would not know whether it's exceeding emissions limits.

 

Do you mean that the 4.2 gets better MPG than the 2.5? That's pretty astonishing if it is indeed the case.

My fuel gauge seems to get worse. It's just above half tank after 170 km. Now, it shouldn't be the engine consuming all that fuel, but I keep thinking "what if". Thankfully it seems that the dealer will take care of it.

well, if not, I'll trade it for a 4.2.

 

An update...

There is something very strange going on. I had the car checked and the exhaust data are, as the tech put it, "near perfect". Yet the least the car has consumed between fills is 12.5 litres/100km (~18MPG), on one fill.

Mostly that figure is up to around 14 litres/100km, though, and that's without me spending my time on short trips.

There's been another few issues with the car so the dealer has graciously agreed to fix the issues, or replace the car. I'm very glad I decided to go to a Jaguar expert when buying my Jag.