I have an 09 2.3 auto with 63k that runs smooth as butter but for some reason my gas mileage has been going downhill. I use to average around 20mpg but now I'm down to about 16. I've kept up on basic maitenance (oil changes, air filters etc). I just cleaned the MAF sensor but that didn't seem to do anything except lower my idle rpms a bit. There is no CEL or obvious problems. Any ideas what to check, clean, or replace?

 

Check things like tire pressure
The braking system.
ignition system
vary your fuel station(could be poor quality fuel)

 

Hey same problem but im an 04. I get 16 mpg right now too and it sucks, it is winter and I have 200 lbs of weight in the back but still.
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Hey man same probleem here I'm a 04 automatic 2.3 and I am averaging 16 mpg highway driving right now which is awful. Im also dealing with intermittent starts issuess though so our cases might not be related. I am looking into the O2 and maf sensorss

 

I just replaced my fuel filter, checked tire pressure which was fine, checked my brakes which were fine, and had a buddy use his fancy computer to check for problems. He said even though there's no CEL sometimes he can find issues on his scanner but he said everything looked perfect. So I'm still scratching my head. Gonna order new plugs and wires today and see if that does anything but I doubt it.

 

Yeah i was thinking new plugs and wires too but that's a lot of effort for what I don't thibk is the problem yet

 

Update me if you do it, we're in this together. I checked my live data and the temp is fine and so is Maf. Is it cold where you are right now? I'm in Canada so it's pretty damn cold here and I have 200 lbs of weight so that might contribute to my low mileage a bit.

 

Last tank average temp was in the teens (Fahrenheit). Been slightly warmer this tank (above freezing) and no difference. I don't carry extra weight in the winter, truck doesn't go out in the snow. I got the plugs and wires (OEM motorcraft stuff). I'll let you know if it makes a difference but given that the old plugs and wires look brand new I'm not optimistic.

 

Okay cool, I'm gonna look into the fuel injectors and see if that could be the problem.

 

Whoa whoa... you're just going to drop new injectors in the truck?
the ECM commands a given fuel amount. If the injectors are dumping more fuel than needed(ie faulty and leaking) the truck will see that as a rich condition. Log your Short term fuel trims, and long term fuel trims to see if they who the truck attempting to compensate for an over fuel condition.

My guess is a mechanical condition on the truck is causing the truck to over fuel on purpose.

 

 

Changed my fuel filter, which was full of black fuel and dirt, and said **** it and ran some Sea Foam through it too, will check mileage in aweek.

 

Dunno if your still following this but after I did the plugs and wires my mileage increased substantially. I'm back slightly over 20mpg city which is where the truck has always been. The old plugs and wires looked perfectly fine to me but I can't argue with results. Got aprox 225 miles per 15 gallons before, aprox 300 miles after.

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Thanks for the update

 

Ron in your vast experience would you say this is just a fluke or would changing the plugs and wires really benefit this much? Im still at a loss, only 65k and the plugs and wires looked good. I mean the temp did warm up into the 40's would that account for so much change? If the plugs and wires were bad I would expect the engine to run rough and have misses rather than just lose mileage? Again like I said... I can't argue with results but I'm still curious.

 

I was working on it but old Whitey got hit by a tractor a month ago and has been laid to rest at the scrapyard.

 

MPG is about engine efficiency
Gasoline engines are not very efficient, 25%, so 75% of the gasoline's energy is wasted in heating up engine/coolant and the air around the engine.
So if a gallon gas is $4, $1 of that is to push you down the road, $3 heats up the planet, lol.
Diesels are a little better, 33%

New technology is getting gas engines up close to 30%, diesels close to 40%

So efficiency comes down to the power the fuel can generate at the crank to push you down the road, if spark plugs and wires are not producing best spark at the best time then there is less power, so your foot has to push the gas pedal down a little more, MPG goes down.
Not misfiring just not full efficient power

There is a precise time in the power stoke when full explosive power(highest pressure) must occur to get best added power to the crank.
Full explosive power needs to occur after TDC, of course, lol, but not too soon after or there is not enough leverage to push the piston/connecting rod down to move the crank
If it occurs to far after TDC then less power is added to the crank
Ignition timing causes spark BEFORE TDC, this is because full explosive ignition takes a little time, milliseconds for flame front to spread, but still time, so piston has moved passed TDC when that occurs, how far passed depends on when spark plug actually sparked, and that has to do with the wires and spark plug itself.
If spark is delayed a millisecond full explosive power would occur later in the power stoke, so less power added to crank

There is no "Power sensor" for an engine, O2s just tell computer if fuel:air mix was correct, and if it is you are getting best MPG for the current engine conditions

Yes, colder outside air makes MPG go down but also increases power, point of CIA(cold air intakes) which is what all Ranger come with stock
Colder air is denser, more oxygen molecules are packed tighter together, so computer is forced to add more gasoline to get the 14.7:1 WEIGHT RATIO
Heavier air means more gas has to be added, which will make more power BUT not as efficiently
Warmer, lighter air means less gas can be added to get same 14.7:1 ratio, more efficient