Filled up and got 15mpg according to the trip meter. Does this sound right for the mpg? It's a fwd so I'm guessing it would be around 25 but I only drive it in the city with stop and go with some freeway.

5 speed? 4-speed?

Factory tire size? Other modifications?

 

IIRC, low 20s was about as good as I ever saw in my 4EAT AWD '6. So you're not terribly low for city driving. If there aren't any other symptoms, I wouldn't mess with it. Maybe take a look at the coolant temp sensor, those can get corroded and nasty and read incorrectly, which would cause it to run rich.

Likely correct for stop and go. The XT has no advantage with it's aerodynamics in stop and go city driving. 

Get an AFR (wideband) gauge and watch it. See what it does. 

GD

8 hours ago, Numbchux said:

5 speed? 4-speed?

Factory tire size? Other modifications?

 

IIRC, low 20s was about as good as I ever saw in my 4EAT AWD '6. So you're not terribly low for city driving. If there aren't any other symptoms, I wouldn't mess with it. Maybe take a look at the coolant temp sensor, those can get corroded and nasty and read incorrectly, which would cause it to run rich.

Where would that be?

I learnt a US gallon was 4.000 litres.

Found Costco gallon of apple juice was 3.890 litres.

Our gallon in Australia was 4.546 litres.

Which gallon are you using?

City cycle is usually worse the greater your engine capacity in the 80s beasts.

Fuel type in use?

Black fumey film around tailpipe bodywork?

Last real tune up? Fuel cleaner for injectors used in recent times?

 

 

 

 

17 hours ago, xXArchusXx said:

Filled up and got 15mpg according to the trip meter.  but I only drive it in the city with stop and go with some freeway.

City stop and go is terrible for gas mileage. It’ll be low and possibly inconsistent.

20 is fairly average for these and FWD doesn’t get waaay more than AWD outside of very specific conditions. 

With long 100% highway trips they can get into the 26-28 mph range in perfect conditions.  but conditions need to be ripe. That’s all highway and not doing 80. The 6 cylinder mileage drops quickly with any idling, city, mountains, etc  

a 6 will respond quicker and drop quicker than a 4 with city, mountain Winter, idling, etc 

if you want to pay attention to gas mileage it’s best to do it on a long consistent trip.  If you have a somewhat regular vacation/hobby/family/work trip, with relatively consistent driving speeds and few stops, use that as your gas mileage base line.

also what is “using the trip meter?  Are you actually dividing total miles by gallons when you fill up ?  If not, then there are probably estimating errors. 

its also winter - car idling while de-icing or brushing snow or ice or letting it warm up or defrost will kill gas mileage too. Gas engines are highly inefficient at idle.

Edited January 12, 20215 yr by idosubaru

I assume it has a knock sensor? they can kill power and economy if bad.

I changed the fuel filter ill see the fuel economy when I take the miles divided by gallons used.

It’s not the fuel filter.
Dragging brakes, CTS, plugs/wires/air filter, check engine light issue...?

The CTS (coolant temp sensor) is the connector and sensor right by the thermostat housing.  They get corroded and are problematic all the time on XT6’s.  All the time. Like I have no clue how many bad ones I’ve seen. 

If it’s bad, the connector usually needs replaced.  I’ve even just soldered each wire directly to the coolant temp sensor terminals.  Install little clips so you have a pigtail to disconnect if needed.  Or get a new fuel injector connector (there’s a generic one that’s identical and fits) and splice it in place. You can try cleaning it all  up it with sand paper or files but it’s a go of work for low grade results. Also take note if the corrosion goes up the wire - sometimes it can go many inches up inside the wiring insulation. 

If you want to easily improve your gas mileage, replace your oxygen sensor.  Then clean, sharpen and regap your spark plugs.

A comment for  Step-a-Toe:

1 US gallon = 3.785 liters

I Imperial gallon = 4.546 liters

4 liters to the gallon is sometimes used for quick and dirty calculations, but not when any precision is required.  The OP was filling his tank with US gallons of gasoline, so they would be the 3.785 liter version.