Hi everyone! So, my 03 Jag Xtype 2.5 is burning waaay more gas than usual. I have replaced the air filter, 4 new tires, changed the spark plugs, fuel filter, used 2 types of fuel additives that helped with acceleration but not gas consumption, all my fluids are good. My alternator is putting out too many volts and I scheduled to have it changed tomorrow but that doesn't really effect it im sure. Any ideas on what to change next????????

 

Define "waaaay nore than usual". What had you been getting, what are you now getting, has anything changed in your driving habits lately (shorter trips, many of them), change brands or grades of gas, any light on the dash or any other issues you have been fighting with on the car?

 

Notthelotion, when you say that the car is going through more gas than usual, are we talking about you have lost say 4-6 mpg, or are we talking that the car is down in the single digits for mileage. Having lived in Norfolk for a few years and now up in Southern Maryland, I have noticed that my X-Type will loose about 4 mpg when the weather is consistantly around 40F (highs) when compared to the summer 80F days. It is due to how the factory programmed the car to handle when the motor is not at temp and running the engine slightly rich. In our case, it is running it probably richer than it needs to be.

 

Well a full tank used take me to about 280 to 300 city miles. Now its about 180-210. My travel habits have not changed and Im still in the same area as when I bought it. As far as gas is concerned I have tried to use different gas stations to find out which one "acted better" in my car. Nothing under 93 grade though. No lights, no leaks, no squeaking, no sound. It gets the same gas mileage for a weeks time when I run it on cold days with the heat on as when I run it for a week without the ac on at all.

 

O yea, and tire pressure is checked faithfully. Unfortunately you cant drive my car and NOT notice when they start to inflate/deflate :/

 

Lotion, ouch. That can definitely hurt the wallet. I would say to first start with disconnecting the battery and forcing the ECU to relearn things. I have noticed over time that the ECU will adapt to the point that it can start hurting the mileage. From there, you may need to check the exhaust system for any damage. It is possible that one of the mufflers has failed internally or one of the cats is getting plugged and is restricting flow. But, both of those should show themselves with a loss of power too.

After that, not sure.

 

I noticed that when the weather got colder there was a noticable drop in gas mileage in my car. It's probably partly just due the the cold weather. I've done all the tune-up stuff to mine too recently and I think these cars being awd and heavier mean they aren't super efficient on gas mileage. I would try resetting your ecu though and just cruise it around more mellow. I noticed when I floored it the other day out of the parking lot it seemed like I almost used up a quarter tank. Since then I've driven it really mellow and the gas has lasted three times as long.

 

I average 220 a tank anyway (not taking it all the way E of course). Its always been like that...if I do more highway mileage I can squeeze 250 out of it but thats it

 

Hi there, you can definitely lose quite a bit in mpg as the weather turns a lot colder.

Here in the UK at this time of year I can lose up to around 5- 7 mpg!!

I see you're at 60k or thereabouts, it may be an isue with your 02 lamda sensors?
Do you suffer from any hesitation / surging of power?

Always a good idea to get any codes read of course although a failing 02 sensor may not show up.

Good luck

 

Can you tell us what the actual mileage is? You mention how many miles you travel between fill ups, but you don't say how empty the tank is. Reset your mileage indicator and see what that says over a tank. Doe3s the car drive fine? Could you maybe have a sticking caliper? I would think to affect the mileage that much you could tell if one or more of the wheels would be really hot and you would probably have excessive brake dust on one wheel.

 

Jim C64, I will try and replace the O2 sensor because there was a surging of power but my alternator was asking out. However the car shifts quickly/early. ECU maybe??

 

The mileage is 64573. By the time I get to about 200 its on the red and about to trigger the light. The only concern, besides my other thread about the alternator, is that the car shifts up quickly. I changed out all the break pads and checked the calipers and they are all good. I did think about the breaking issue and there is no brake dust really.

 

You wouldn't by chance have the sport button depressed would you?

 

I don't know what's wrong with yours, but I get around 350 miles out of a tank of premium on the highway, even in the winter. 3.0 v6.

 

Is the engine warming up to normal operating temperature? Does it take forever to do so?

 

Likewise, I see significant differences summer vs winter

I get :

summer highway say 110-120kmh - around 10 l/100km vs 11 or 12 in winter

summer short errands about town - around 12.5 to 14 versus 16 to 19 in winter

The colder it gets and the shorter the journeys made, the worse it gets.

Overall, we seem to get around 11.5l/100 summer versus 14 in the winter.

I know the car is good because i every so often drop the highway speed to around 80 to 90, reset the computer and see what it reads over 10 miles or so - usually around 7.8l/100km - and usually accompanied by a chorus of disapproval from the boss - quite right! it would drive me nuts if my chauffeur did that to me too!!!

 

OK well as a result of using the SeaBreeze juice for the engine through the gas tank, I have been getting 100 more MPG!! And this is while the heater on all the time because it has been really cold here. I guess there was just a build up of gunk on the inside. I am all about saving money and learning the do's and dont's along the way. So far, SeaBreaze has been the answer. OH, and have limited the type of gas stations I go to. A lot of them are not honest about what type of gas they put in the spots. For example, some places actually put regular in all three spots. I know a guy who drives fuel trucks and fuel the stations and knows first hand about the dishonesty.

 

Bracester, Your Jag is the prettiest I have ever seen! I like the way it looks; the simplicity of it. Simple is sexy. Great Job

 

There are usually four major reasons for significant drops in fuel mileage (if all the maintenance is up to date)

1. Bad upstream O2 sensors. (Recommend replacing every 75-100k miles)
2. Partially clogged Catalytic Converters
3. Coolant temp sensor faulty.
4. Mass Airflow Sensor faulty.

Good luck and let us know what you find!