Major drop in fuel economy recently

[MikeG537]

Recently I had my evaporator replaced due to a defective one and several months later my fuel economy has plummeted! I took my vehicle back to the dealer and they said it must be a different issue because the evaporator replacement has nothing to do with it. I have a new filter, my tires are properly inflated, the intake ducts are not clogged, and there is no check engine light to make me think that I have a bad sensor. Any other suggestions? I also notice a slight decrease in power as well. I have approx. 97,000 miles. Any help or suggestions would be appreciated.

 

[Jon M]

Fuel system service. Clean the injectors, throttle body.

No check engine light doesn't mean there aren't faults, just that they're not sufficient to have turned it on yet. There could be codes stored that would indicate a problem. A scan tool will read them, CEL or no CEL.

 

[peterk9]

Recently I had my evaporator replaced due to a defective one and several months later my fuel economy has plummeted! I took my vehicle back to the dealer and they said it must be a different issue because the evaporator replacement has nothing to do with it. I have a new filter, my tires are properly inflated, the intake ducts are not clogged, and there is no check engine light to make me think that I have a bad sensor. Any other suggestions? I also notice a slight decrease in power as well. I have approx. 97,000 miles. Any help or suggestions would be appreciated.

Welcome to the Forum Mike.
Have you ever had a tune up done on it? Plugs should be replaced at 100k miles according to the Manual.

Peter

 

[MikeG537]

Thanks guys! I am close enough to 100k to get a tune up I guess right?

 

[KelvinC]

My MPG's have also fallen. I'm near 100k so I replaced my plugs and brakes and haven't seen an improvement. Still trying to figure it out.

 

[peterk9]

My MPG's have also fallen. I'm near 100k so I replaced my plugs and brakes and haven't seen an improvement. Still trying to figure it out.

Did you by any chance switch gas brands? Some brands have up to 10% ethanol and I think that will reduce MPG. As well, many companies use 'Winter gas' during the appropriate season which may also affect mileage. Engine air filters can also affect mileage.

Peter

 

[machine4321]

I made the mistake of talking while filling my oil at my last oil change and over filled by at least an half a liter or more(my driveway is on an angle too). I then went on a 4000km road trip and knew 1/4 way through something was up. I managed to drain enough into a plastic container to get it to normal and things were back to normal. I was only getting 12l/100 on highway when I normally get 10 if not better.

Just a thought if they did oil change at same time .

 

[MikeG537]

I got my plugs changed, my air filter is clean, there are no leaks, oil change, properly inflated tires, i use the same gas (i even tried using a higher octane fuel), and I even added fuel injection cleaner... although the power has been restored the mpg is still falling.

 

[KelvinC]

Did you by any chance switch gas brands? Some brands have up to 10% ethanol and I think that will reduce MPG. As well, many companies use 'Winter gas' during the appropriate season which may also affect mileage. Engine air filters can also affect mileage.

Peter

No ethanol, same brand of fuel, and no change in driving habits. Maybe it's wind and speed. I'm averaging (mostly highway) about 20MPG. If I baby it I can get about 22 on the highway - I used to get ± 23-24. Thank you for the thoughts!

 

[kmarnes]

My fuel economy tanked the moment I purchased something called the 3.5L Ecoboost engine in the Sport. I have consistently achieved 18L/100km since day 1 (8 months now) and I've tried 91 octane premium without ethanol -- and mileage never budged. Now I just use ethanol spiked 87 regular and I still get 18L/100km and no longer input accurate data during each fill up. I do almost entirely city driving and I drove more aggressively when I first bought it, and now I'm more relaxed -- the engine just eats gas at the same rate no matter how I drive or what I put it in.

For you Americans, that's 13mpg. I do get much better economy with highway driving, but I've only been on the highway a half a dozen times in 8 months, and only 1 of those were trips longer than 90 minutes.

Of course, I'm being slightly sarcastic... but my serious observations and tests over the first six months haven't really resulted in any discernable difference in economy or performance based on fuel types. I'm also not towing over mountains, but for day to day city driving, cheap 87 octane fuel with ethanol is the winner for me.

 

[Sopher]

My 2017 Sport gets 16.9 mpg on average. That's combined city and highway. People are forgetting the 3.5L Ecoboost IS THE SAME ENGINE that's in the F150.
My 2009 F150 Lariat only got about 15-17mpg too.

 

[613GT500]

Now that I'm back on all-season tires and the gas stations have purged all winter gas; I'm still averaging around16mpg-17mpg.
As stated above, the 3.5L EB wasn't meant to be fuel conscious.

 

[peterk9]

According to Fuelly.com, since the end of January my average MPG has been 18.1 (U.S.). My last fill up was April 19th a few days after the Winter tires were taken off so I don't have any updated figure. My driving would have been about 60/40 hwy/city driving.

Peter

 

[Napalm]

After checking things like mileage and tune up work. (plugs, clean injectors, air filter, etc)

Don't for get things like O2 sensors (they wear with time too) and your PCV system. Unless you have a catch can - you might need to clean that out.

Then - the part often overlooked - the car itself. Make sure all your pieces are still in place correctly - you don't have bits loose on the bottom or your parking brake drags.

Clean out your radiator from the back to the front to get all that dirt and bugs and whatever out of there - if there is any.

Give the car a good once over occasionally to make sure the rest of it in is order. Had a neighbor complain about the fuel econ in his taurus the other day - front air dam was cracked in half. Patched it together and he went back up 2 mpg on his next fuel up. Aero matters - on the highway. City MPG falling - often clogged injectors and or airfilter and throttle body.

 

[Pete6114]

After checking things like mileage and tune up work. (plugs, clean injectors, air filter, etc)

Don't for get things like O2 sensors (they wear with time too) and your PCV system. Unless you have a catch can - you might need to clean that out.

Then - the part often overlooked - the car itself. Make sure all your pieces are still in place correctly - you don't have bits loose on the bottom or your parking brake drags.

Clean out your radiator from the back to the front to get all that dirt and bugs and whatever out of there - if there is any.

Give the car a good once over occasionally to make sure the rest of it in is order. Had a neighbor complain about the fuel econ in his taurus the other day - front air dam was cracked in half. Patched it together and he went back up 2 mpg on his next fuel up. Aero matters - on the highway. City MPG falling - often clogged injectors and or airfilter and throttle body.

Seizing calipers will show up if one keeps an eye on the MPG, which i did on my truck. Ford recommends brakes to be checked and sliders cleaned/lubed yearly.
As far as the EX goes, since it's my wifes vehicle and i dont drive it much, all i know is that the tank size could be larger....

 

[machine4321]

Seizing calipers will show up if one keeps an eye on the MPG, which i did on my truck. Ford recommends brakes to be checked and sliders cleaned/lubed yearly.
As far as the EX goes, since it's my wifes vehicle and i dont drive it much, all i know is that the tank size could be larger....

Good call! I basically relube and clean up back brakes every oil change as I really dont want to put another set of wheel bearings/rear brakes in again.

With the EX in park no park brake on can you move the the car back and forth just by pushing, pulling using the tire only?

 

[J_C]

If you have (one of) the Ecoboost engines, remember that this is expected as the valves get more and more carbon buildup.

http://www.enginebuildermag.com/2015/01/direct-injection-engines-carbon-deposits/

The link above mentions a chemical cleaner through the intake. Do not put one through the turbo.

Definitely pull the OBDII pending trouble codes and if you have a more advanced scan tool that can look at real time running data, that (or taking it to a shop for this service) should help.

 

[peterk9]

Another interesting read; http://www.autoguide.com/auto-news/...a-problem-with-direct-injection-engines-.html

Peter

 

[Lovemyxlt]

About 2 weeks ago I changed the oil on my 2013 xlt and since then the truck started driving as o/d is off. Lag in changing gear, low fuel economy. I drive 30 MPh and when I let go of gas the rpm still stay at 1300 and I can hear the engine. This never happened before and no one knows what's wrong or how to fix it.

 

[peterk9]

About 2 weeks ago I changed the oil on my 2013 xlt and since then the truck started driving as o/d is off. Lag in changing gear, low fuel economy. I drive 30 MPh and when I let go of gas the rpm still stay at 1300 and I can hear the engine. This never happened before and no one knows what's wrong or how to fix it.

Welcome to the Forum.
Have you conformed that overdrive is not turned OFF?

Peter