So I ran down my first full tank on my ranger this last week and averaged 15 mpg. A total of 292 miles before the next fill up. And it's a 99 2.5L 4 cylinder. The first half a tank had me quite excited actually because I got 200+ out of it. Then, I don't know what happened, but the last half only got me around 80 miles. I'm very disappointed in that.

I didn't not WOT the thing.

I did not speed or go over 75 in the 2 times I used the highway.

I did not sit in traffic.

I did not have unnecessary or excessive (not even 200 lbs) of weight in the truck.

I did use A/C but I religiously shut it off when the windows are down (say, at a drive thru or in town) or if I'm in slow traffic. (I'm in Franklin TN right now and it's beautiful here so I roll the windows down when I can)

Most all driving was at constant speeds of 30-60 mph with me getting the truck into TC lockup speeds as much as possible.

The truck doesn't pull or slow down excessively when I let off the gas.

I understand I have 4.10s, but 15 mpg average, is 1 mpg less average than my old big block 5.4L V8 6000 lb Ford Expedition. And that's terrible.


Chime in please.

 

Check for stupid stuff - like brakes sticking - under-inflated tires, retarded engine timing. Weak thermostat. Thorough tune up is in order sounds like. Old fuel or maybe winter blend and gasahol won't give good numbers, that stuff just disappears like magic. O2 sensors and the like may be lunched?

 

i would go to the nearest autozone and have them do a free scan and see what codes you get and write them down and post them here

 

I have a code reader and I've scanned it many times before. All I have is a P1401.


Is there a CEL on these trucks because I can't see one when starting it.

 

Yes there is a dash located CEL & if not burned out, or not removed, it should light up for it's self check each time at KOEO before we crank the engine, or if we have a set trouble code it'll remain lit after the engine is running, or it'll blink if we have misfires with the engine running.
Sounds like the previous owner ignored the P1401 & the lamp burned out, or the po has removed the lamp so they wouldn't have to look at it.

P1401 trouble code is for the DPFE sensor high input. The DPFE sensor provides the engine computer with the feedback it needs to control EGR/how much of the engine exhaust poo the computer is gonna make the engine eat. It's fed back to the engine by the EGR valve to control detonation. An acting out EGR control can affect fuel trim & that can affect drive ability & mpg, so is a good suspect for your sudden mpg woes.

Double check its electrical connector pins/sockets/wiring for damage or corrosion & its vacuum line back to the intake manifold & it's high temp rubber exhaust gas feedback hose that runs down to a connection below the EGR valve. These hoses can bake out, split, leak, come off, or the small feedback port that's inside the EGR valve end hose connection can become plugged with carbon & cause mischief, so would need cleaning.
Of course the vacuum line between the DPFE sensor & the intake manifold port needs to be tight fitting on both ends & no dry rot cracks along its run such that its leaking vacuum.
If all that checks out, suspect a faulty DPFE sensor. Motorcraft or BWD are recommended.
Get the P1401 trouble code put right & then post up how mpg goes.
Let us know what you find.

 

It seems I have a lot of vacuum issues with this truck although I'm not finding any leaks. If I wanted to clean up the whole vacuum system, what all do I need?

 

just to eliminate something my mind jumped to, how did you get your mileage number? Did you fill it up, drive, then fill it up again then divide miles driven by amount of gas put in? Also, you say that you got 200 miles out of the first half tank, but 93 out of the second half. sounds to me like the gas gauge is acting out.

Maybe/maybe not stuff. But came into my head as possible things to think about.

 

My gauge has always been waaaay optimistic for the 1st 200 miles, then it drops like a rock. To know true mileage requires doing the math mfp4073 suggested.
If the fuel pressure regulator vacuum line were leaky, you would get more fuel pressure than expected, at least on the systems with vacuum modulated regulators. If the regulator failed, same story, mileage about 1/2 of normal, ballpark.
The other ingredient in mpg calculations is knowing your mile meter - odometer - is reporting correct distance. If you have a pessimistic odometer, you'll get (calculated) poor fuel economy. You can 'ballpark' using the mile markers on the side of an interstate by watching for a sign, and noting the odometer reading as the sign passes the front windshield pillar. Watch for the next sign, and note whether the meter recorded an additional mile at the time the sign passes the pillar. I would do it for a 5-10 mile run to average out my 'pillar' observations and the variance in the mile markers placement. Some report they are not as accurate as expected in their placement. YMMV. heh.
tom

 

When my truck was stock, 2000 2.5, manual, 4:10, I got 23-25mpg and without being a lead foot, I got as high as 27-29mpg.
The caliber sliders froze up on me and my mileage tanked to around 15mpg.
Make sure your front calibers are working smoothly.

 

I figured the number by filling the tank completely, and then resetting the trip meter. When the the gas needle hit E (not something I like to do but I did it to calculate the fuel mileage) I pulled into a gas station and refilled. The trip meter said 292 at that time. I'm at a half a tank now, with 173 on the trip, but I've been driving without as much concern over the fuel mileage this tank.


The brakes on all 4 corners need work, but I don't believe any are sticking. When I find myself starting to speed (5-10 mph over) sometimes on flat ground (down side to no cruise control) and let off for several seconds, I'm still speeding. I have to touch the brakes whenever I need to lose any speed unless I'm going uphill or I hit the O/D off button.

I'll take a drive tomorrow after work and check the ODO.

This truck is now concerning me as all my ball joints, shocks and bushings are gone (sway bar has no connection on the passenger side) and the bed doesn't line up with the cab. I feel like this was an old farm truck for someone, and their son got a hold of it and jumped the truck.... I'll hope not though. Haven't noticed a bent frame. But that's completely unrelated.


I put new bearings up front last Thursday. I'm gonna change the rear diff and trans fluid this next week. Redo all brakes, and put together a order list for the suspension so all that will be left to bring this truck up to date, is the timing belt. Which I'll handle at 120,000 miles.

 

Ford 05hg:I pulled into a gas station and refilled.

Okay, gauge on E, how many gallons? I would expect to use 12-13 gallons.

If your fill-up was 12 gallons, you are getting around 25mpg. The tank on mine will be on "E", but there are about 3 gallons left at that point. I think it is about a 16 gallon tank.
On one trip, I filled up, reset the trip meter, and drove, watching the gauge more closely after 250 miles. I knew the tank capacity, was doing highway driving, and figured I would/should get in the 25mpg range, and did the math. Tank showing empty on the gauge, and 300 miles is about 12 gallons. I knew the capacity was over 14, so knew I should have 2+ gallons left, and could reasonably expect to do another 30-40 miles without running out of fuel.
I may have the capacity wrong, but anyway decided I would drive to the 340 mile on the trip meter before worrying. When I finally filled, I still had over a gallon left, if I remember properly. The fuel gauge is an indicator, and not a very good one.
tom

 

and then you do some simple math like 292miles/gallons you just put in. Right?

 

These are 19.5 gallon tanks am I right?

 

1999
reg cab, short base 16.5G
reg cab, long base 20G
extended cab 19.5G

 

That makes sense then. I've got the smallest tank so I guess it's averaging 25 mpg. Very nice.

Although you're now making me wish I had a long box. I'd love to get 500 miles between fill ups.