Consistently decreasing MPG over the life of this truck ... normal?

[Rob Lymburner]

I've kept track of all but a handful of my mileage stats on each fill-up and have noticed consistent degradation of MPG over time. Nearly straight line - is this to be expected? Northern Virginia driving.



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(btw hi old-timers! first post in ~3 years)

 

[Jacob Dryer]

Plugs, wires, TB clean, tires and tire pressure all would degrade over time along with MPG. I'm sure there are other items too, but that is the quick list.

 

[Rodger Tellefson]

In addition to what JDBoxes said above, change your gas filter a minimum of once a year. Clean the MAFS with CRC Electrical cleaner or CRC MAFS cleaner. Change your serpentine belt too. Get a SCT XCalibrator III with an appropiate tune from Torrie at Fastpartsnetwork.com (site sponsor).

 

[Todd Z]

Both my 03 and 04 run pretty consistent with MPG......



Check your maintenance and driving habits, Normally thats the root cause..



Todd Z

 

[Richard L]

As previously stated. It's not normal unless you have not maintained the vehicle. Your original 21+ MPG was very good and is about as good as it gets for highway mileage. Dropping to 15-16 MPG is not too dramatic and is typical of a mixed city/hwy mileage



Also keep your tires inflated to at least 36 PSI, use synthetic oil, and don't haul around a lot junk in the bed. Dragging around unneccessary weight will kill your gas mileage.



It is also possible that your state/city has changed their fuel blend and added more alcohol, or you are using a different gas staion who blends in more alcohol into your fuel that is hurting your mileage. Try switching brands of gas.



Finally, perhaps over the past nearly 9 years, the traffic has increased due to more people moving into your area, highway construction,, more traffic lights, or new scholls being built that increases traffic int that area. I know that two new traffic lights have been added to my route to work, and when schools in session, traffic near the school is very heavy. The school used to be a High School, but the built a new HS and the old HS is now a Middle School....So now there are more parents dropping off and picking up kids and they have added crossing guards that were never there when it was a HS.



Lots of things effect mileage, and some are under your control, while others are not.



...Rich

 

[Rob Lymburner]

Thanks for all your suggestions and thoughts. I have maintained the vehicle with regular oil changes (synthetic every 5k) but not sure I've had the gas filter changed, or certainly not in a long time. Looks like I have to make an appointment with the dealer and give it a good once over.



Love this truck, and although its showing some wear & tear, I hope to hit its second century mark.

 

[Dreman]

I still get 19-20 mpg highway on my 2003 with 173k miles. I just filled up last night with 21.5 gallons for 410 miles, and before that it was 22.3 for 430 miles! (Got a little close on that one!)



No mods, synthetic oil, freeway driving in the 65-75 mph range.

 

[George Berta]

I don't think I have ever gone less than 350 miles before putting gas in my ST.I think that conditions may play a big role in mpg though.Many people I have talked to say the cold or extreme heat do more to lower mileage than simple wear and tear.I did notice that more alcohol was in gas the further north we went.Do you fill up with that more?

Here in South Ga and central Fl I hav been rock steady,but when I head to the mid west I see a 5 mpg drop almost as soon as I cross in to Kentucky.

Good luck with the next century-lol

G

 

[Kevin Palmer]

The simple fact that it is a nice and smooth loss is a perfect indicator that something has lost its performance.



As mentioned above, plugs, wires, filters,,,



An older engine with HIGH miles can loose some MPG due to compression issues, but I cannot believe you fall within that parameter..

 

[Gavin Allan]

I vote increasing amounts of ethanol being added to the fuel over the past several years. :angry:

 

[Gypsy me]

Have not read all the posts but remember, seasonal mixes of gas can make a difference too.



Winter gas mixtures do not give as good of miledge as say the summer gas mixtures.



Miledge does degrease with time but with proper maintenance and little things to help the miledge will give you much more mpg. changing to a bigger exhaust, cai, the plugs new wires. I have an 04 and always have gotten on the average 24-25 mpg over the road STOCK. In town, averaging 17-19 mpg stock, well the only thing I have that is not stock is the Zabtek TB.



Using cruise control when you can, is another simple thing you can do to help with your mpg. Lighten your load in the bed if you have alot of stuff in it, extra weight in the bed can play with the mpg....



and this sounds silly but better supsension, tires all can play into it as well.



Alot of dive bombing stops or fast take offs can hurt your mpg.



These are just a few things off hand I can think of.



Again I have not read all the posts so forgive me if I have repeated some things.