Poor Gas Mileage

[Franklin Jones]

How are the plugs? Still original? Probably worn out and need replaced.

I had the same experience on my 14 with 105k, 8-9mpg, and when I dropped new plugs in it it jumped to 13 in city.

O2 sensors are next on my list.

 

[ManUpOrShutUp]

Of course I'm not saying you weren't getting 19-20 MPG "before", since I'm not you and not there BUT I find it very difficult to believe any 2012 Expy EL would get 19-20 MPG under any conditions other than a tailwind or downhill. I get a bit less than 18MPG (best) on my 2014 when I'm cruising level ground on the interstate going 65. 5.4L

Hope its OK to say this. Not being a ******.

This is straight highway driving in my '11 EL and only holds up as long as I'm cruising at moderate speeds, but it is doable.

 

[sjwelds]

How are the plugs? Still original? Probably worn out and need replaced.

I had the same experience on my 14 with 105k, 8-9mpg, and when I dropped new plugs in it it jumped to 13 in city.

O2 sensors are next on my list.

Question for the collective:

Can an O2 sensor not throw any codes, and yet still negatively impact fuel economy?

 

[bobmbx]

Question for the collective:

Can an O2 sensor not throw any codes, and yet still negatively impact fuel economy?

Oh yeah. Thats generally how it happens, btw. The sensor is providing ********, but still "in range" data, so the PCM thinks the data is correct and starts making fuel trim changes.

 

[Plati]

Question for the collective:

Can an O2 sensor not throw any codes, and yet still negatively impact fuel economy?

There was a guy posting a while back about that. His claim was that O2 sensors are an item that should be periodically replaced, even with no codes. Sort of like replacing plugs. I think I saw another post about how you can get the data the O2 sensors are providing and make a decision about how "healthy" they are. The guy claimed it can be a big hit to MPG. Pretty expensive to replace I think so it seemed like money chasing money. I've been curious about that since I saw it.

 

[Franklin Jones]

The upstream O2 sensors are how the PCM determines the quality of the burn and how much fuel to inject.

The downstream only monitor catalytic converters efficiency.

So if you want to replace them for MPG purposes, you only need to replace the upstream ones.

 

[Aspen03]

I've experienced this a couple of times on previous vehicles. Reading live data is about the only way to see if they are "tired" or not. Knowing what the mv ranges correspond to afr wise is necessary if you want to really determine how they are performing.

They're fairly inexpensive to replace...$30ea I want to say when I ordered some Denso's for my in laws expy a while back. Considering the impact they can have on fuel economy it wouldnt take long to recoup if it is the issue. 100k miles is more than enough to warrant replacement if they are original even as preventative maintenance.

 

[TobyU]

There was a guy posting a while back about that. His claim was that O2 sensors are an item that should be periodically replaced, even with no codes. Sort of like replacing plugs. I think I saw another post about how you can get the data the O2 sensors are providing and make a decision about how "healthy" they are. The guy claimed it can be a big hit to MPG. Pretty expensive to replace I think so it seemed like money chasing money. I've been curious about that since I saw it.

I would say that mostly that was just a claim.
People have been lying about fuel mileage for decades.
The auto parts stores and manufactures like Bosch have been saying you should replace your oxygen sensors every so many thousand miles for fuel mileage also but they have a vested interest in selling oxygen sensors.
I'm sure they can get lazy but I would hook up a live monitoring scan tool and watch what they're doing.
If I were going to swap some out to test I would make sure I bought some very economical ones on eBay.

 

[Blksmk]

368 mile highway run at 70 mph with 25 to 35 mph wind I got hand calculated 14.88 mpg

 

[tommyddsr]

So I just bought a 2009 EL a few weeks ago. Previous owner did not clear the onboard computer and it read 9.2 MPG average. I figured he must have towed a trailer or something. Long story short, best I could do was 11 - 12 MPG, city/hwy. Put new plugs in it last week even though it was running smooth. Now getting 20.4 on the HWY (60 MPH on Cruise Control for approximately 100 miles) and 14.9 city. And for the non-believers, here is the screenshot to prove it. Loving life in the new Expy now.