Horrible fuel economy

[heffer86]

I have done been driving almost 600 miles and I have an average of 16.1 MPG. My current tank has an MPG of 13.9 MPG with 118 miles. Am I crazy or is this horrible economy. My 2018 2.7 always hovered around 20 MPG and I am driving the same.

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[20acrefarms]

You appear to have a check engine light on. Maybe something is wrong?

 

[KBKEITH]

Yeah, that doesn’t seem quite right unless your right foot is extra heavy. Take a look in the MPG Data Points thread to see what I, plus some others are getting with our 2.7s.

 

[KBKEITH]

You appear to have a check engine light on. Maybe something is wrong?

Good catch.

 

[ZWARRIOR]

@KBKEITH What MPG showed when you bought your truck? Mine was 11 or so, on the 90 mile drive home, I reset the trip calculator and the trip showed 25mpg, while the "all time" MPG was something like 18. On my trip to sacramento 230 miles. I did a new trip, and it showed 26mpg while the general all time mpg got to 22.5 . The first trip that I started the second I bought the truck is showing 23.5.

Since the original MPG started super super super super super super super low you have to give it time to catch up to your actual mileage.

 

[KBKEITH]

@KBKEITH What MPG showed when you bought your truck? Mine was 11 or so, on the 90 mile drive home, I reset the trip calculator and the trip showed 25mpg, while the "all time" MPG was something like 18. On my trip to sacramento 230 miles. I did a new trip, and it showed 26mpg while the general all time mpg got to 22.5 . The first trip that I started the second I bought the truck is showing 23.5.

Since the original MPG started super super super super super super super low you have to give it time to catch up to your actual mileage.

That’s a great question. I really have no idea as to where my MPG was when took it home. Good point that you make, though.

 

[ZWARRIOR]

That’s a great question. I really have no idea as to where my MPG was when took it home. Good point that you make, though.

Yeah I would just start a new trip, that should give you a more accurate MPG calculation

 

[Bryan Simon]

@KBKEITH What MPG showed when you bought your truck? Mine was 11 or so, on the 90 mile drive home, I reset the trip calculator and the trip showed 25mpg, while the "all time" MPG was something like 18. On my trip to sacramento 230 miles. I did a new trip, and it showed 26mpg while the general all time mpg got to 22.5 . The first trip that I started the second I bought the truck is showing 23.5.

Since the original MPG started super super super super super super super low you have to give it time to catch up to your actual mileage.

I have the v8 in mine
4x4 ext cab 8’
on the drive home from the dealer it showed 11mpg.
just for sport and amusement I have not reset that counter, but start logging hand calculated mileage on “trip 2
over the course of 2 months and 1900 miles, the original counter has gone from 11-19.6. Still creeping up albeit slowly

Trip 2 shows (last I looked at it) 20.3

Actual ( filling at same station, same pump, and pointed in the same direction) mileage is coming out to 19.3.

I’m guessing the next fill up (tomorrow or Friday) will show a slight improvement over the 20.3 on the dash and 19.3 calculation.

I don’t really drive like a little ol’ lady, but I have very little city traffic.
And once on a freeway—80+, but if not on the freeway, unencumbered roads with varying 30-50 without frequent traffic control.

 

[NoSnow]

I would also suggest you do the calculation manually. Your computer could be way out as comparted to real world calculations.

 

[heffer86]

So I picked from the dealer and reset it for my trip home. That is my "Trip 1" It was around 150miles and I averaged around 20-21 on that trip. I have left "Trip 1" as a lifetime MPG total. "Trip 2" is my most recent fuel up. I reset after every fuel up to test with.

As for the check engine line I was told it was an exhaust sensor. The dealer said the part was on national back-order and has no idea when it will come in. He said it's fine to drive the truck, but the check engine light will be on the whole time. I looked the codes up in Forscan and they were: P0141 and P2096

 

[BaySide1]

I have found that different Brands of gas get better mileage than others. Also, gas mileage is lower in the colder months than summer due to the temps and blends of gas (winter/ summer)
in my 2018 2.7L TT I averaged about 17.1 -18.4mpg all winter. during the heat of the summer, I was getting 25mpg at some points but averaging about 22.5mpg. About 90% of my driving is on the highway.
On the highway, 75mph seemed to be the sweet spot. anything over 2000 rpm on the highway uses more gas.
So far, have 1600 miles on the new 2021 Lariat Super Crew and it appears to be roughly the same.

 

[Knickell]

I’m getting pretty poor mileage too. It is part and parcel because of:

 

[Pedaldude]

There's no such thing as an 'exhaust sensor,' though there are sensors in the exhaust. O2 sensors for gas engines and EGT sensors in diesels.

indeed P0141 looks like an O2 sensor fault code.

P2096 is a fault code indicating that the O2 sensor is detecting a 'too lean' condition. Which is the result of either not enough fuel being injected for ideal combustion, or a bad O2 sensor that thinks it's the case.

A too lean condition can destroy an engine, especially a turbo engine in short order. So the ECM will dump as much fuel as it can into the engine to keep that from happening. So regardless of if you are driving aggressively, or simply idling your engine, with the two fault codes present, your fuel injectors, at least on one side of the engine are working overtime injecting as much fuel into the cylinders to avoid detonation.

On older vehicles, running rich, meaning too much fuel is being used to support combustion, will only result in reduced power and unburned fuel exiting the exhaust for all to smell and breathe in. It's something that was once common place but now only experienced when a classic car drives by or the landscapers come with their gas powered lawn mowers and two-stroke leaf blowers and weed whackers.

On a modern catalytic converter equipped vehicle, a too rich running condition, over time, can damage the converter through overheating and clogging.

The catalytic converter isn't designed for removing unburned fuel (though it will), it's primarily meant to superheat partially reacted molecules like CO and fully convert them into the less dangerous CO2. To do this, it's constructed of a fine honeycomb of ceramic on which platinum group metals are deposited to react with the exhaust gasses. This reaction happens because platinum group metals are good oxidizing catalysts and have been used in hand warmers and lamp mantles starting in the 19th century. When you start dumping unburned fuel directly into the cats, the result is overheating and coking up the fine openings because the design limits have been exceeded, that's why larger engines have bigger converters.

Driving a few miles to have a bad O2 sensor replaced won't permanently damage the converter but ignoring the check engine light and driving around for an extended period of time because a disservice advisor told you to will. The dealership that told you that it's okay is being disingenuous, a good dealer would have taken the O2 sensor off an unsold truck and not let you damage your vehicle and suffer poor fuel mileage.

A cursory look shows that the part # is new for 2021 and it's possible that like many other parts, it's backordered, however, O2 sensors are not proprietary to Ford and it looks like aftermarket parts are available. There's a very real possibility that last years part will work if it uses the same threads and the specs match, the 2021 part may have only changed their wire connectors, that's really only something that Ford would know but for something that is critical to the operation of the engine, if a workaround is available to technicians, it should be provided. It's a pretty common practice for older vehicles that have obsolete parts, to replace the sensor with one that matches and hardwire it because it's unavailable with the proper connectors.

The other possibility, is that your O2 sensor isn't bad but that the connector wasn't fully plugged in and worked loose.

Hopefully the original poster isn't still driving around with a bad O2 sensor after a month. I used Rockauto, since Parts.Ford isn't working right now.

 

[Ritchie457]

I have done been driving almost 600 miles and I have an average of 16.1 MPG. My current tank has an MPG of 13.9 MPG with 118 miles. Am I crazy or is this horrible economy. My 2018 2.7 always hovered around 20 MPG and I am driving the same.

I just completed a 120 mile trip with my 2.7L and got just under 27 MPG for the entire trip. I like those numbers!

 

[heffer86]

There's no such thing as an 'exhaust sensor,' though there are sensors in the exhaust. O2 sensors for gas engines and EGT sensors in diesels.

indeed P0141 looks like an O2 sensor fault code.

P2096 is a fault code indicating that the O2 sensor is detecting a 'too lean' condition. Which is the result of either not enough fuel being injected for ideal combustion, or a bad O2 sensor that thinks it's the case.

A too lean condition can destroy an engine, especially a turbo engine in short order. So the ECM will dump as much fuel as it can into the engine to keep that from happening. So regardless of if you are driving aggressively, or simply idling your engine, with the two fault codes present, your fuel injectors, at least on one side of the engine are working overtime injecting as much fuel into the cylinders to avoid detonation.

On older vehicles, running rich, meaning too much fuel is being used to support combustion, will only result in reduced power and unburned fuel exiting the exhaust for all to smell and breathe in. It's something that was once common place but now only experienced when a classic car drives by or the landscapers come with their gas powered lawn mowers and two-stroke leaf blowers and weed whackers.

On a modern catalytic converter equipped vehicle, a too rich running condition, over time, can damage the converter through overheating and clogging.

The catalytic converter isn't designed for removing unburned fuel (though it will), it's primarily meant to superheat partially reacted molecules like CO and fully convert them into the less dangerous CO2. To do this, it's constructed of a fine honeycomb of ceramic on which platinum group metals are deposited to react with the exhaust gasses. This reaction happens because platinum group metals are good oxidizing catalysts and have been used in hand warmers and lamp mantles starting in the 19th century. When you start dumping unburned fuel directly into the cats, the result is overheating and coking up the fine openings because the design limits have been exceeded, that's why larger engines have bigger converters.

Driving a few miles to have a bad O2 sensor replaced won't permanently damage the converter but ignoring the check engine light and driving around for an extended period of time because a disservice advisor told you to will. The dealership that told you that it's okay is being disingenuous, a good dealer would have taken the O2 sensor off an unsold truck and not let you damage your vehicle and suffer poor fuel mileage.

A cursory look shows that the part # is new for 2021 and it's possible that like many other parts, it's backordered, however, O2 sensors are not proprietary to Ford and it looks like aftermarket parts are available. There's a very real possibility that last years part will work if it uses the same threads and the specs match, the 2021 part may have only changed their wire connectors, that's really only something that Ford would know but for something that is critical to the operation of the engine, if a workaround is available to technicians, it should be provided. It's a pretty common practice for older vehicles that have obsolete parts, to replace the sensor with one that matches and hardwire it because it's unavailable with the proper connectors.

The other possibility, is that your O2 sensor isn't bad but that the connector wasn't fully plugged in and worked loose.

Hopefully the original poster isn't still driving around with a bad O2 sensor after a month. I used Rockauto, since Parts.Ford isn't working right now.

Thanks for the detailed information on the codes. I was in the dealer about a week ago and they did replace an O2 sensor. Now I am wondering if any harm was done to the engine. I drove it ~300 miles with the before I got it into the dealer. They said it was a sensor and I could keep driving it. I drove it another 200 miles after that. So ~500 miles total with everything out of wack. I am just shy of ~1000 miles now. Is there anything I should look for before I hit my 3yr/36mile warranty?

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