Fuel Economy I get only 11MPG after Spark plug change

[Ikkesh]

140 miles and 12 gallons later.. = mpg

Just changed Sparkplugs, PCV Valve Oil, working on FPR and Fuel filter now..

also noticed Oil on spark plug #4 someone told me valve cover gasket?

[etlsport]

check the gap on your spark plugs

[VCAMILO]

Seems normal to me. I get about 11 MPG with normal driving around town.
20 gallons = 215 miles. Sometime with higway use I get 260 per 20 gallons.

[Gussie2000]

I got about 400 miles on one single tank.

When i left my house friday morning my odo reading was 48058,when i get back to NYC from binghampton my odo were 48511 so probably getting the best mileage per gallon a VX can ever get :rolleyes:

[Hotsauce]

Bad mileage could be O2 sensor.

It could also be tires with offroad pattern tread, or underinflation.

It could be bad alignment or dragging brakes.

John C.

[Riff Raff]

Hmmm, another factor may be your right foot needs to be weighed and recalibrated.

[Gussie2000]

Hmmm, another factor may be your right foot needs to be weighed and recalibrated.

That one is a BIG,BIG factor riff raff.

I don't drive the VX hard,press the gas pedal little by little & let the horse gain speed enough to keep up with traffic,also use 93 octane fuel or 89,avoid using the 87 as much as i can.keep tires inflated to manufacturer's recommendations,avoid hard stops & hard accelerations,on high ways use your cruise control & avoid tailgating so no need to be braking constantly.

All those driving behavior helps improve mileage a lot.

[TheGanzman]

I've never gotten less than 15mpg, nor more than 17mpg; in fact, the VX exactly mirrors my former Jeep Wrangler. I run stock tires religiously maintained at 29 pounds, no back seat, no spare, and I would say that my driving habits are "average" as far as acceleration/braking, except that I seem to be better than average at judging when to slow down in anticipation of a traffic light change, so I'm pretty easy on the brakes (compared to my wife, LOL). I've also never gone through a total "highway tank" yet...

I also know that at least one of my friends, if I loaned my VX to HIM to drive, would consistently "accomplish" 11mpg; a LOT depends on your driving habits!;)

[LittleBeast]

Yupe I accelerate just like I am starting in the 100m dash and I have huge tires, heavy rims, leave my back seat in more than not, and don't mind smashing the pedal down to pass slow pokes, and I average around 12-14mpg. :bwgy:

[PittVXr]

11 MPG is about what I am getting too. To be fair I do zero highway driving. 90% of what I do is stop and go city driving of under 5 miles per trip. Still I think I should be able to get a little closer to 14-15 mpg. I'm riding on 235/70 highway tires inflated to 38 psi and I try to avoid quick starts from a stoplight. I've tried a bunch of fuel additives (Lucas, STP, Gumout) and they did nada for me. I'm thinking of changing the plugs and O2 sensor too see if that makes a difference.

[VehiGAZ]

It could be bad alignment or dragging brakes.

John C.

The two times my mileage dropped down to 12-13 mpg from my usual 14-17 mpg was due to a seized brake caliper.

[Jolly Roger VX'er]

I've noticed my mpg really jump up with warmer temps (I know about the blend switching of gasoline from winter to summer).

Even on my trip to Moab/Vegas/Malibu last year...when I went to the west coast via the mojave desert (rte I15) my gas mileage shot up to 23mpg on the highway. I was barely getting 17mpg before that in the "colder" climates of other states. My trip to Vermont with temps in the '90s yielded 23mpg there & 22mpg back.

This winter the mpg in my VX after 2" lift & 32" MT tires has been pretty low although I hadn't computed it I can only say I went from 350+ miles per tank of all around type driving down to around 265 miles per tank.

With Spring now trying to kick in and warmer temps plus change in gas blend...I'm now finally seeing some improvement..looks like I could top 300 miles this tank!


My VX is the first vehicle I've ever owned that seems to like hotter weather as far as gas mileage. My theory..the driveline fluids & engine oil thinning out & the tire temps going up!

[Joe_Black]

140 miles and 12 gallons later.. = mpg

Just changed Sparkplugs, PCV Valve Oil, working on FPR and Fuel filter now..

also noticed Oil on spark plug #4 someone told me valve cover gasket?

Have you tried resetting the ECU?

[Gussie2000]

I've noticed my mpg really jump up with warmer temps (I know about the blend switching of gasoline from winter to summer).

Even on my trip to Moab/Vegas/Malibu last year...when I went to the. west coast via the mojave desert (rte I15) my gas mileage shot up to 23mpg on the highway. I was barely getting 17mpg before that in the "colder" climates of other states. My trip to Vermont with temps in the '90s yielded 23mpg there & 22mpg back.

This winter the mpg in my VX after 2" lift & 32" MT tires has been pretty low although I hadn't computed it I can only say I went from 350+ miles per tank of all around type driving down to around 265 miles per tank.

With Spring now trying to kick in and warmer temps plus change in gas blend...I'm now finally seeing some improvement..looks like I could top 300 miles this tank!


My VX is the first vehicle I've ever owned that seems to like hotter weather as far as gas mileage. My theory..the driveline fluids & engine oil thinning out & the tire temps going up!

You can't be more right about this situation,my VX also behave the same way yours whenever the weathers goes up the better mileage you gain from a gas tank.
All that happens because the fluids & oils has more density during cold season & takes much time to warm up;That's why is so important to use the right oil & fluids to help improve vehicule's performance

[VehiGAZ]

My VX is the first vehicle I've ever owned that seems to like hotter weather as far as gas mileage. My theory..the driveline fluids & engine oil thinning out & the tire temps going up!

All my vehicles have always shown better mileage in the summer, although some decreased a little when it got hot-hot (>90*F) out.

I've always thought that the lower air density in warmer weather might have had something to do with the improvement in mileage, too.

I think I'll write to Car & Driver and see what the automotive engineers on staff there have to say about it.

[Jolly Roger VX'er]

All my vehicles have always shown better mileage in the summer, although some decreased a little when it got hot-hot (>90*F) out.



yep..this is what I was trying to say earlier :o


My other vehicles with exception of the VX always followed this trend of starting to get worse mileage as it got hot-hot (>90*F). I found it puzzling when my VX would jump alot higher (better mpg) as the temps soared,,,,,bring on global warming...lol.

[VehiGAZ]

PS - not all states have different fuel grades summer vs. winter. Some switch to a lower vapor pressure grade in the summer to reduce gas evaporation - a huge contributor to smog.