Very Poor Gas Mileage

Not sure if this post is in the right place. I recently purchased a 2010 Escalade with the L94. My Long Term fuel Trims are near perfect and they fluctuate between -2 and +2. I have only had the truck about a week and half. I have ordered new O2 sensors, both upstream and downstream. A new MAP sensor. A new MAF sensor. A new PCV hose and a cold air intake. I also have a 2007 Yukon Denali that is getting better gas mileage. Also seems like it takes less money to fill the tank on the Escalade. Maybe there is an issue with the floater or the tank itself. If anyone has had similar issues or any ideas of something I may have missed, i'd greatly appreciate any input. Also buying new plugs and wires. Possibly headers while i'm at it lol

Why are you replacing all those sensors? Did the computer throw codes for them?

What is your average speed for a tank of gas since you bought it? How far did you go over how much run time?

How are you calculating your gas mileage over your 1 week + ownership? By hand or are you trusting the computer? What mileage do the two SUVs get?

How about a comparison between the Escalade and the Yukon -- engine displacement, diff ratios, driving routine, different drivers, etc.?

I don't know what to tell you my average is around 9.6 no matter what (gm) I drive
you can expect mpg to increase comparatively to how much you ease up on the big pedal
my wife can drive the same vehicles and get 13+ I taught her to drive but she still doesn't go as beast mode as I do.
I have found that for me it doesn't matter the vehicle, it's just HOW I drive.
you could drive yours and get 17 and then I could get behind the wheel of yours and get 9.6
unless it's detectably running like garbage then things like a bad cat can cause a noticeable drop in mpg which you can sort of determine by the temperature of the cat
you could also maybe look at things like the torque converter.

AmunRoo said:

Not sure if this post is in the right place. I recently purchased a 2010 Escalade with the L94.
My Long Term fuel Trims are near perfect and they fluctuate between -2 and +2. I have only had the truck about a week and half.
I have ordered new O2 sensors, both upstream and downstream. A new MAP sensor. A new MAF sensor. A new PCV hose and a cold air intake.
I also have a 2007 Yukon Denali that is getting better gas mileage. Also seems like it takes less money to fill the tank on the Escalade.
Maybe there is an issue with the floater or the tank itself. If anyone has had similar issues or any ideas of something I may have missed, i'd greatly appreciate any input.
Also buying new plugs and wires. Possibly headers while i'm at it lol

Click to expand...

At the very end, you mentioned headers ...
'Funny' thing is, I very strongly suspect you have a leak somewhere between the MAF and the O2 sensors.
Most likely, an exhaust manifold leak. Less likely but still possible, an intake manifold leak.

These leaks would normally show up as LTFT's off by more than +2 or -2, though.
You can try switching your MAF sensors between vehicles, see what happens ...

did he ever say what bad mileage is?

A few years ago we had a fella join up after he bought a new 6.2 Tahoe. He immediately complained about the poor gas mileage. Turns out the fella lived in downtown Miami and the truck rarely got out of the city or even past 35 mph. All that stop and go in the city had him at around 9 mpgs or so.

I finally convinced him to take a Sunday drive to Belle Glade for a hamburger and then he realized that his truck got good mileage once it was able to stretch its legs and run at a constant speed.

I'm at 8.7 mpg, use lots of E85, slightly quicker than traffic, all city, 5.3, 3.08..
I probably need to check tire pressure..

He mentioned one costs more to fill..
Is the tank filling up all the way? (fuel guage full?)
Or, like he said, the level sensor is off, reading empty before it actually is?

AmunRoo said:

Not sure if this post is in the right place. I recently purchased a 2010 Escalade with the L94. My Long Term fuel Trims are near perfect and they fluctuate between -2 and +2. I have only had the truck about a week and half. I have ordered new O2 sensors, both upstream and downstream. A new MAP sensor. A new MAF sensor. A new PCV hose and a cold air intake. I also have a 2007 Yukon Denali that is getting better gas mileage. Also seems like it takes less money to fill the tank on the Escalade. Maybe there is an issue with the floater or the tank itself. If anyone has had similar issues or any ideas of something I may have missed, i'd greatly appreciate any input. Also buying new plugs and wires. Possibly headers while i'm at it lol

Click to expand...

You've got a lot of good answers above on gas mileage. 70% of it is not controllable (weight, motor, gearing, actual roads/traffic and speeds driven), but the other 30% is quite controllable, and as @Doubeleive stated, it is almost exclusively in how you manage your gas pedal.

Regarding the less money to fill the 2010 Escalade versus the 2007 Denali, the 2010 Escalade has a 26 gallon gas tank, and the 2007 Denali has a 31 gallon gas tank.

A lot of great responses. Thank you all very much. I appreciate it. So to answer some of the questions, I drive the trucks exactly the same. My foot is just as heavy on the Denali as it is in the Escalade. The displacement between both trucks is the same. Only difference is that Yukon has the l92 and the Escalade has the l94 with AFM. I was under the assumption that I would have better gas mileage since it automatically switches between four and eight cylinders but I guess that's all just hokum and fairy tales LOL as far as calculating gas mileage, I wasn't running off what the dummy screen tells me. I'm basing all of this on distance traveled and how much the needle moves on the gas gauge. As an example, I live in Illinois and a round trip to Kankakee from Chicago is pretty close to 140 miles. The Escalade left me at a quarter tank while the Denali will only run about half a tank. I have the short body Denali not the XL so I do have a 26 gallon tank in each truck. At least I think I do. I need to do a physical inspection on the Escalade. Once I'm down to about an eighth of a tank, it only fills up with about 15 to 16 gallons which does lead me to believe that there is an issue with the floater. I am changing all the sensors because the truck is new to me but it does have 121,000 miles and it is 14 years old. I don't know when the sensors were last changed and I figured a refresh won't hurt. I just installed and cold air intake and all the sensors are on order. I do plan to replace the stock muffler with a Magnaflow straight through bullet muffler and remove the cats. The headers I'm going to replace because the current factory manifolds are rusted beyond belief. I don't think I have any leaks as I'm not throwing any lean codes. I think I'm going to do a smoke test and see what I get out of it. I did notice that the oil filler neck is pretty loose and it might be a source of air intrusion. I do understand that these trucks are heavy and it's also a big displacement V8. I do a lot of long distance driving so my fuel mileage should be better in the Escalade. That's just an assumption and a poor one at Best LOL I'm going to drive around for a few days with the new Cai and see how it does. I'll post updates. Again thank you all for the responses.

Also, the Denali has full exhaust, no cats, headers, c a i, high flow water pump, all aluminum three row radiator. So it runs cooler and has a more free-flowing exhaust.