I have a 2004 D2 SE7 with 149xxx.
I am getting a whopping 9mpg city and highway.
There are no codes pending or other wise.
LTFT runs between 0.0 and 3.8%
Idles at 650 after the SAI gets done

parts replaced:

all O2 sensors with walker brand
MAF with a Bosch brand
remanned bosch injectors
upper plenum gasket
IACV
Air Filter
CAT system
180 degree Thermostat
TF 2” MD lift
Wrangler 265/75/16 tires.
Front Drive Shaft
TF Muffler delete

 

That’s poor for sure. Do you have a scan guage or similar to check your cruising mpg?

 

I do. Its hard to watch. I will have to screen record a 5 mile highway drive and post it.

 

Check your compression, mpg that low with no codes is something the computer can't see, like low compression.

 

You can have vacuum leaks that don't throw codes which also reduce mpg.

Also as far as I know the ECU does not have a mpg function, it relies on the user to input when they fill the tank and it does the same math you would do manually.

Thus with larger tires the ODO and Spedo will be wrong and so will the scan tool.

The only real way to measure accurately is the old fashioned way, driving a known distance as measured by GPS or maps app, starting with a full tank, then filling again at the end and doing the actual math.

 

Are any of your brakes dragging?

 

These discos are so picky if you have any exhaust leaks or vaccum leaks it tells you right away

good point on the brakes.
Make sure it’s not dragging


how many miles do you physically go on a full tank ??

 

I usually never take her down past a 1/2 tank. I am going to let her rip with this tank and report back. . . The brakes are new up front, but see bo signs of dragging.

 

Hi

had exactly the same problem with my 2003 V8 Discovery ... removed the MAF .... gave it a good spray with MAF cleaner ..... put it back in and away it went and mileage went back to normal.

all good

Darren

 

Neither of my Disco 2s have ever done much above 10mpg. No vacuum leaks, good compression, new ignition and intake components, no brake drag. My Ultragauge usually shows me hovering around 10.5 when I'm cruising at 65-75mph.