Poor Fuel Economy

[jarz21]

I'll start by saying that I do recognize that driving habits greatly affect the gas mileage of any vehicle. In this case, that may be partially true, but I'd like to cover all of my bases first.

My '92 2.3L (just over 100k miles) 2wd 5-speed only averages between 18 and 22 mpg. Most of the driving that I've done with it so far has been on the highway, though I also use it to drive 2 miles to campus several times a week. I replaced the spark plugs (which were extremely worn) and the plug wires. I have also replaced the air and fuel filters, just changed the oil & filter, and have changed the transmission fluid. The PCV valve is new. The tires are properly inflated. I now find myself having to downshift less on hills on the highway, but the fuel economy isn't any different than before all of these services.

What could be causing this seemingly poor fuel economy? If it were something like a bad EGR, wouldn't the truck run like crap or not idle? Could it be an oxygen sensor or something? I'm quickly running out of ideas, and it really bothers me that my gas mileage is almost equal to that of my stepdad's 4.0L Ranger. Had I known this would be the case, I may have opted for the extra power!

Kevin in PA

 

[BlackBII]

What gearing and size tires are you running?

 

[Dave R]

IN addition to the questions above...

Have you done a compression check?

Have you scanned the computer for trouble codes?

Is the truck lacking on power?

Automatic or manual tranny?

 

[jarz21]

The truck has the stock 14" tires, and stock gearing (whatever that would be for the Mazda 5-speed manual tranny and rear end combo they put into the 2.3L XLTs in '92).

I have not done a compression test. I had no real reason to suspect valves or rings, so hadn't bothered checking. The only test I did for codes was for the rear ABS because that warning light is on, but the check engine light isn't on or anything. This is the newest vehicle that I've ever owned, so I'm still learning what a lot of these crazy electronic systems do. All I know is that things were far more simple on my '64 Plymouth Valiant, and that even got upwards of 18mpg!

After reading through some other random threads, I did end up going out and disconnecting my battery for about 5 minutes. It does seem reasonable that some things may need to reset on occasion, and I haven't had the battery disconnected since I did all of the work.

Kevin in PA

 

[jarz21]

And as far as lacking power, I really have no idea or means of comparison. I'm assuming that it has about as much power as a 100hp Ranger could possibly have. It still cruises at 70+ on the interstate, but has a little trouble on the occasional hill.

Kevin in PA

 

[scotts90ranger]

try resetting the computer and go from there. you should be getting around 25-27 on the highway, that's what I got back when mine was a stock 2 whweel drive... now I get 19mpg no matter how I drive being a 4x4 on 31's...

if the engine has been trying to compensate for not getting enough fuel or air (dirty filters) or not getting enough spark (bad plugs), it could still be thinking nothing changed, it takes a while for the computer to learn itself better, I should know, a couple weeks ago I spent over 2 hours letting an engine learn itself clean when I knew exactly where to hold it speed and load wise (on the dyno using a computer to watch it), the emissions test was way better after though, it went from not passing to passing with flying colors, get to start the process again tomorrow on a different engine

my mileage did decrease suddenly a couple years ago too, went from 26 to 23, but I blamed it on winter fuel, then I didn't drive as much after that, and when I started driving more I was converted to 4 wheel drive... I am getting an EGR code though, which I have a spare valve in the garage waiting to go in...

 

[Buckeyes903]

I wish mine would get 18-22 MPG, I'm only getting around 12-14, but the 6 inch lift with 33 inch 12.50 tires and having the 2.3 doesn't help

 

[jlloyd]

I have a 95 with the same setup and I also get about 18 to 19 mostly in the city.I have 14 in. wheels and 3;45 rear-end and bone stock everything,Jim