Possible causes of a decline in MPG

[410Fortune]

DOOR STICKER you are looking for the door sticker and the axle code listed on the sticker
much easier then climbing underneath with flashlight, although that is fun

 

[koda2000]

DOOR STICKER you are looking for the door sticker and the axle code listed on the sticker
much easier then climbing underneath with flashlight, although that is fun

OP has stated:
"The vehicle VIN sticky tag is nearly wiped clean of its writing."

 

[410Fortune]

Ahhhhhh whoops I missed that. I have seen that a time or two myself
Axle tag it is!

 

[ptf18]

Fellows: Some what "chilly" this AM but I managed to get the 3 O2 sensors changed. Not too difficult as the 3 unscrewed much easier than I expected. The electrical connectors were a bit tricky but did came apart. The Bank 1 # 1 connector was a stretch for my arm but I removed the fender liner and could access it.

Well...... S/T runs fine. I attached my scan tool and took o2 reading. Don't know what I'm looking at but the POST -CAT sensor is more or less flat line after I had driven the S/T to get the engine to operating temp. Previously the POST-CAT sensor would oscillate some what erratically. The readings of the 2 PRE-CAT sensors seem to oscillate more frequently then they did prior to change out. And at a more steady rate.

I checked fuel trims and from what I "learned" on the 'net they are GTG.

Anyways the wife drove it to work and said all was fine. I "think" if I see better fuel mileage I'll say I "fixed it".

Need to use the scan tool more. Pretty neat....but dopn't know what I'm looking at.

I'm "tempted" to change out the 3 sensors in my '02 Ranger Edge with 200k on the dial.....just because.....

I'll keep you all posted.

ptf18

 

[CDW6212R]

Very good. Now you have more peace of mind about those items, they'll last many more years.

 

[koda2000]

Yes, I'm pretty sure those new O2 sensors will easily outlast the rest of the truck as it has 220K on it.

Hopefully the new O2's will get the fuel mileage up again. In my experience, worn out O2 sensors don't always set the CEL. The heated ones are recommended to be changed at around 100k, so the OP's were way overdue to be replaced.

 

[oklagp1200r]

I also let my oxygen sensor's go 200,000 miles before change no cel or change in fuel mileage before change and no fuel mileage change after. Always average 16 to 17 mpg of course city/highway depending on idle time, weather etc. Get about 20 to 21 mpg on long highway trips with a 2001 4x4 model at 60 mph. I have 207,000 now!
The rearend grease should be changed initially at about 1,000 miles so you can get all the break in contaniments out then every 30,000 to 50,000 miles depending on if you tow, off road, boat ramps, etc.
Transmission fluid initially at around 10,000 miles then every 30 to 50,000 miles depending on items quoted above! JMO
Keep your IAC valve, throttle body and MAP sensor clean regularly for these can and will affect MPG and idle quality.