Looking for thoughts on sudden drop in gas mileage

[Nuke001]

Hoping that someone might have some thoughts on a sudden drop in mileage . . . .

Have a 4.0L 2006 Explorer XLT with about 130K on the clock. About a month ago I had plugs and wires replaced . . . I know, should have done them myself but 12 hour days took my free time.

Before that I was getting around 17 - 19 MPG combined around town / highway driving.

After the replacement, I checked it about a week later and it was in the 14 to 15 range and then it dropped down to 10 to 11 MPG which is where it was this evening when I filled up.

Driving style has not changed. Checked and there are no codes appearing. Had the mechanic check it and he did not find anything amiss. The truck tracks straight so I do not think there is a brake dragging. There are no odd driving noises that I can hear.

So any thoughts on what you suggest looking at to look into this mileage drop . . . 10 - 11 mpg is way too low for this size engine.

Thanks for any input you might have

 

[BrooklynBay]

The cold weather might have something to do with it. Cold air creates a denser mixture plus the engine works harder until it starts to reach the normal operating temperature. Winter gasoline is also different since it contains ethanol. Are you using a thin grade of oil?

 

[Nuke001]

The cold weather might have something to do with it. Cold air creates a denser mixture plus the engine works harder until it starts to reach the normal operating temperature. Winter gasoline is also different since it contains ethanol. Are you using a thin grade of oil?

It is colder for sure here in Michigan but the truck warms up within a few miles of the house in the morning . . . as far as oil, changed it in October and used the regular grade so it has not been changed for the winter months

 

[grfo]

Some random thoughts,....
Are you sure no one is siphoning gas out of your tank?
Are you sure you don't have a leak?

Alcohol enriched gasoline does not get as good gas mileage as pure gasoline because the air fuel ratio difference.
That would not account for that dramatic drop but it will contribute to some of it.
Tire pressure being low will hurt it some.

I generally see worse gas mileage during the winter. Is the engine getting up to operating temperature? It will not run as efficiently as it can until it does.

Short trips in cold weather are murder on gas mileage.

Worse mileage probably indicates it's running richer?

Fuel and air filters recently replaced?

It is in your best interest to get this figured out quickly because everything down stream that can potentially be ruined by a rich mixture like the oxygen sensors and catalytic converters are very expensive to replace.

 

[tripplec]

THE COLD weather will make a visible difference. Head to a warm place or wait till spring and see.

PS: We all use more gas when its cold, and emit it as well.

 

[Tech By Trade]

Mine always drops a couple points on winter gas. That and my winter tires and warm up time kills the numbers.

 

[07EddyB]

As long as I've owned my Explorer (V8) mileage has gone down in the winter. I can pretty much tell you when my normal gas station got their first load of winter fuel. I don't pay that much attention to mileage anymore - but I can still tell you when that happens. During the summer my Ex rarely kicks out of OD during my daily commute. Every winter, it does quite often. I lose a lot of torque during the winter on that fuel. Lately, with temps in the single digits and winter fuel in the tank I would be looking for a problem if I didn't already know what it was given the reduction of torque my engine is putting out.

 

[MotorCityFats13]

things dont work as well when its cold and winterblend gas is the real culprit ..... they add all that isobutane and butane even though they claim it only loses about 2% energy ive always felt that was total BS..... also if you warm up your engine you lose alot of fuel that is not being used to move from A to B..... ive gained 2mpg just from staying inside for lunch break

but with all of the confounding factors from thermal expansion, winter driving speeds, variation in rolling resistance, and other winter behavioral differences its best to just move to mexico!

 

[michael loibl]

I agree, cold starts and short trips kill gas mileage. I only have a 2 mile ride each way to work. I give it one minute idle time and then drive extra gently for the first 2 minutes which is all local streets for me as the temperature slowly climbs. Total trip takes about seven minutes each way.
If it wasn’t for me working most Saturdays at a second job 15 miles away, and the occasional road trip, my oil would be a sludgy mess of water vapor and combustion byproducts which would never burn off.

 

[Zorin]

My 2006 Eddie Bauer V8 hates cold. Just to give you an idea, and I keep pretty good records -

When it was warmer out, still warm enough to use the air conditioning, I was averaging 19.4 MPG per tank of fuel.

Now that it is absolutely butt-cold, my average is down to 16.8 MPG.

This is with the same route, and filling at the same fuel stations, and only topping up to the nearest nickel. My route is 46 miles one way, 99% of it on the highway with very little stopping - just slowing from 65 to 50 as I go through small towns on my way. I drive 6 blocks on surface streets to my office, and my house is a quarter of a mile from the highway. (I live in south central Kansas - my backyard is an 800 acre wheat field....so I commute a LOT.)

Tim

 

[MotorCityFats13]

My 2006 Eddie Bauer V8 hates cold. Just to give you an idea, and I keep pretty good records -

When it was warmer out, still warm enough to use the air conditioning, I was averaging 19.4 MPG per tank of fuel.

Now that it is absolutely butt-cold, my average is down to 16.8 MPG.

This is with the same route, and filling at the same fuel stations, and only topping up to the nearest nickel. My route is 46 miles one way, 99% of it on the highway with very little stopping - just slowing from 65 to 50 as I go through small towns on my way. I drive 6 blocks on surface streets to my office, and my house is a quarter of a mile from the highway. (I live in south central Kansas - my backyard is an 800 acre wheat field....so I commute a LOT.)

Tim

I keep wonderful records too and with the 4.0 I drive 40 miles a day 5 days a week "about a 70/30 highway/local road split" and summer blend I get 18's and winter 15's..... I still find it hilarious how the V8 beats the V6 in every category and yet people still 1. ordered these and 2. ford kept building them..... the way I feel is the V6 should of been illegal..... my best trip up north 250miles was in the 19's speed locked in at 75-80 and never used the brakes for 3.5 hours