My 2000 XLT with a 5.4 and 119,000 miles seems to be getting really crappy mileage. I know the Expeditions are well known for this but burning nearly half a tank and only going about 110 miles seems a bit much! I keep up on the maintenance pretty well and it has a good air filter,just had tranny serviced last weekend and spark plugs are being done this weekend. Not sure if the plugs will help anything as I have been told both ways....but I'm sure they need to be done. I did a fuel filter about a year ago and am thinking about doing another one along with the plugs. I have ran Seafoam through it (not through the brake booster yet but that will be happening too) No engine lights or anything like that (although I have had to do 2 or 3 coil packs).Is there anything else outside of an on board computer to help this out or is this just the way it is? I did notice that the 4WD drive switch only has the 3 settings of AWD,4hi and 4 low and most of the time it is in AWD. It runs great and I really like it but this mileage thing really sucks. I figured mileage awhile back and it was like 8 or 9! I would appreciate any input on this. Thanks!
Another thread about crappy mileage
- Thread starter bar422
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Assuming your not lifted and running larger tires you should be doing much better. I am now getting over 12mpg around town with mine and I am not exactly a hyper-miler.
If your not experiencing misfires I would lean towards failing O2 sensors or possibly bad cats.
If your not experiencing misfires I would lean towards failing O2 sensors or possibly bad cats.
Last edited:
1997SCEBFEX
Full Access Members
I agree w/ Tom and your plan of attack to assist!
other things to consider:
- has it been an extremely hard winter where you are? in other words, are you occasionally lugging around wheel wells full of snow/ice/debris?
- do you do a lot of in-town/idle-in traffic driving?
- have you changed fuel purchase location and perhaps got a bad tank?
- what extras are in the back behind the 3rd row seat area?
- properly adjusted tire pressure?
- do you have any problems with your brakes; could one be dragging, or the e-brake?
PanHandler.
other things to consider:
- has it been an extremely hard winter where you are? in other words, are you occasionally lugging around wheel wells full of snow/ice/debris?
- do you do a lot of in-town/idle-in traffic driving?
- have you changed fuel purchase location and perhaps got a bad tank?
- what extras are in the back behind the 3rd row seat area?
- properly adjusted tire pressure?
- do you have any problems with your brakes; could one be dragging, or the e-brake?
PanHandler.
alaskanexpy
Full Access Members
do you let it idle to warm up in the mornings?
i regularly see 8-10 mpg all winter long.
i regularly see 8-10 mpg all winter long.
O2 sensors can become less sensitive with age. As they fail they tend to read lean which is good from a safety standpoint but bad for fuel economy as this causes the pcm to add fuel. This may go unnoticed for some time till it sets a code or runs rich enough to cause other symptoms because it runs fine otherwise.
If you can log the O2 sensor readings in real time it will fluctuate rapidly between rich/lean. As they age the response becomes much slower.
You can try resetting your pcm and if your fuel milage improves (temporarily), I would recommend replacing your front O2 sensors. The pcm should adapt fairly quickly so the difference may not last long. Generally resetting the pcm will cause a loss in fuel economy till it adapts but not if faulty O2 sensor already have it running very rich.
If you can log the O2 sensor readings in real time it will fluctuate rapidly between rich/lean. As they age the response becomes much slower.
You can try resetting your pcm and if your fuel milage improves (temporarily), I would recommend replacing your front O2 sensors. The pcm should adapt fairly quickly so the difference may not last long. Generally resetting the pcm will cause a loss in fuel economy till it adapts but not if faulty O2 sensor already have it running very rich.
Last edited:
Canadian Expy
Full Access Members
I was told from a Bosch tech guy O2's wear out after roughly 10yrs will not throw codes but will not work well.
1997SCEBFEX
Full Access Members
+1 on O2 sensors; not hard to change and may be all the difference.
PanHandler.
PanHandler.
FordandPolaris
Full Access Members
There are two before the front cats, and two after the rears. Change the ones upstream first, that is if you can get them out... I could not break mine loose to save my life. They make a special kit that you can rent out at any o'reilly's or autozone. It helps a lot, but I unfortunately was still unsuccessful, hard to generate good torque on those upstream sensors. I currently am also feeling the fuel economy woes.
Last edited:
Spark plugs are all changed and so are the 2 Oxygen sensors before the catalytic converters.............I suppose I should fill it up and see how it does now. If all goes right it will get the Seafoam in the brake booster treatment tomorrow........Thanks for all the input on this and any more would be appreciated!
1997SCEBFEX
Full Access Members
Good deal!
Similar threads
