Some stats' on VX mileage

[cascabel3]

About two months ago I installed the scan gauge which I purchased through Tone. This gadget will give me everything one can imagine, especially MPGs at any time. So for those with an interest in why they are getting the mileage that they are, here are some stats I have taken while driving for the last two weeks. Bear in mind that all figures are still approximations as I am guessing inclines and declines. I use the Nitto tires hence have calibrated the scan gauge for a 9% increase in tire size:

on frwy flat 65mph = 20mpg
on frwy flat 55mph = 23mpg
uphill grade 65mph~3% = 15mpg
downhill grade 65mph~3% = 34mpg
uphill grade 65mph~6% = 9mpg
downhill grade 65mph~6% = 45mpg

City driving is where I noticed using a lot more fuel. Hard accelaration will cut into your fuel use very quickly. I add 9% to the mileage per gas tank to make up for the tire size. On 65mph in cruise control, I can average 19mpg if it is mostly flat. The hills cost a bit of fuel. Window is up for the most part and AC was off. I believe that a lot of us tend to punch our VX, fast take-offs and speedy driving. This will cost you. I drove a little more gentle for a while and ended up putting 300 miles on the tank, where I filled 18 gallons averaging 16.6 mpg. This included at least 50% city driving.

[SPAZZ]

well my VX only gets 12 MPG and I accelerate normally and it sucks gas. If I accelerate slowly to the point of unsafeness then it doesn't suck gas as much...but if you accelerate normally then it doesn't help.

I'm talking if I acclerate to the point of slowness that I am the only car that can make it through the green light then it doesn't suck as much gas, but we should not have to drive like that to get the mileage that was stated to us from the manufacture.

[SGT.BATGUANO]

S/c'ed 16-17 mpg average with a medium heavy foot

[Wulfgott]

Spazz, is your poor gas mileage due to modifications?

If not, when was the last time you cleaned out the EGR?

Wulfgott

[cascabel3]

Spazz,

12mpgs? Something is wrong. What is your tire size and pressure?

I remember just how much gas mileage improved on my Unimog, taking the tires from 35psi to 50psi. The tires were rated for 50psi. And as you are in Idaho, a lot of mountain driving and curves?

[mbeach]

His truck is not exactly stock.

Our VXs average between 17 (mine, tires) to 20 (hers, stock) in mixed highway and city driving.

[Joe_Black]

My bought-new 2001 VX averages 17MPG and my eBay 1999 IronMan VX with 130,000 miles averages 19MPG. We've got an '01 Trooper 2WD with the 3.5L and it averages 19MPG as well. My two previous 4WD Troopers, a '93 RS and '95 Limited, both had the 3.2L DOHC and each averaged 17MPG (the RS was a 5-speed). All ran 100% Mobil-1 and K&N filters as the only engine mods, although I now have the Morgan-Tec on the 2001 VX which hasn't affected mileage.

[transio]

I get about 12-13 mpg, too. But I have a lead foot.

[SPAZZ]

my VX was straight stock as it was off the showroom floor. At that time it only had 30 miles on the odometer. I filled it up with 89 octane gas which is California's lowest Octane due to the detergent they put in it to help save the ozone by providing better emissions. Due to this detergent being added the octane couldn't be lower, plus being at sea level anyway means you can not use too low of an octane.

From purchase date till 12,000 miles on the odometer, my VX was getting 400 to 410 miles per tank. Then it started to get 300 miles per tank. Replaced fuel filters, had injecters flushed and cleaned out, cleaned EGR, replaced Pcv, replaced spark plugs, everything lubed, greased, and any fluid that could be, changed out. to no avail. It still received 300 miles per tank till it hit 18,000 miles on the odometer and then it started to get 200 miles per tank. mind you that, my VX was still bone stock.

THen I did the fluid change thing again, filter changes again, egr cleaned, injectors cleaned, etc.... but, I installed a fuel miser, tornadoe, and a Calmini air filter. This boosted my mileage up to 230 to 260 Miles Per Tank. and this is where it stayed and is still the same.

So, when I did change the axle gears out from 430's to 456's and installed the interceptor, and went with 32x11.5x17 inch Super Swampers, installed rock slider bars, diamond plate skidplate, Chrome molly Tie rods, Chromemolly sway bar disconnects, and the stinky fab heavy duty rear drag bars, extra yellow top battery, rear storage box loaded with crap, and not to mention the 6 or 7 boxes of Dynamatt xtreme, and I started carring around all my tools(200 pounds), 12 inch speakers and 400 watt amp plus all the heavy wiring, full size spare on top, Yakima extended load warrior, Tow hitch, winch bumber, Warn XD9000 winch, and about 4 extra sets of rock lights under neath the VX as well as the purple neons, extra auxillary fan, etc. after all that I still was getting around 260 miles to the tank. Changing the gears out when I went with the larger tires brough me back closer to stock readings, but not exact.

The only thing that I have changed since then would be I removed the rear seats and went with 305 70 17 Goodyear wrangler MTR's. Now the reading says that I am only geting 200 miles per tank...but I need to find some 477 axle gears to make the reading more accurate .

for a small slant 6 cylinder engine this should not be the case.especially when it was only just shy of weighing 4000 punds stock...mine tipping the scales at around 5,000 pounds...considering that I was at the tire shop and they had a lexus off the ground with the hydraulic lift and the door just happen to be open so I read the weight of it. It weighed more than the VX stock as well as mine with all the heavy crap added to it. It was over 5,000 pounds in weight and those POS's get better gas mileage than our VX's stock.

Bottom line the VX sucks...in mileage and is the crappiest investment in a fuel economy vehicle, but it functions offroad and that is mostly why I bought it. I'm just saying that I might as well have a big 8 cylinder engine in it if it wants to get the mileage of one.

[mbeach]

My wife's last vehicle, a Mitsubishi Outlander, came with a 2.4L 140hp banger. It averaged 17mpg.
That little, underpowered wheezer (same as comes in the Galant, Eclipse, etc.) was just plain working too hard trying to push the 'ute around.
I suspect it is the same with the VX.

Spazz,
I've admired the pics in your gallery for some time (excellent references to the location of various bits of the VX -you have a talent for taking pictures of the right things), and was under the impression that this mileage drop was a result of all of the mods.

Granted, the VX isn't the greatest on gas, but then again I would've bought a hybrid if that were my priority.
I think that it's mileage is respectable when you compare it to the other vehicles in it's class -think Jeep xj/yj/tj/zj/wj or a Series II Discovery.

[cascabel3]

I've got to say, I have seen all the pics in Spazz' gallery and there are some awesome ones. I wanted to add that I have the calmini airfilter and mobil 1 oil in the engine. I remember when I bought the car in Arizona and drove straight back to LA, with the stock tires averaging 85mph I still got 18mpg. After I put on the Nittos this changed however, now that I have the calibration for the tires on the scan gauge I realize I need to add almost ten percent to my actual miles per tank calculations. If living in hilly country, I really noticed just how your mpgs drop going uphill. Parts of Idaho I have been to where as beautiful as they were mountainous.

[Raque Thomas]

I am absolutely shocked when I get over 16mpg with my VX! Full to dead empty (the hard way) was 265 miles. That was combo city/hwy. Did 2 back to back trips 150 miles each with no "run-around" miles (so, all highway) and got 16.6 MPG------wooohooo! Speed was 75 and I don't jackrabbit off the line. Only mod is a drop in K&N filter and 285/55 tires (3% difference from stock in diameter). I had this kind of mileage before the tires were installed. When I first got her, I'd get 320 - 340 miles before a fill up, before the idiot light came on. Now 260 and the light is on.

[Wulfgott]

Wow, Spazz, you say you got 400 to a tank stock when you first got it? That must have been sweet for the short while it lasted. I average about 300-330 on mine now (pretty much stock) with 61K on it and a decent lead foot. My trips are almost always more than 70 miles though each way, pure highway. I live in Vic-Ville CA, and commute to work everyday near Anaheim CA. I wish I could just squeeze that extra mileage out, so I could make it one final trip before having to refuel. I hate stopping mid trip hehe

Wulfgott.

[cascabel3]

Wulfgott,

Victorville???? I travel through Victorville every other weekend on my way to Joshua Tree. If you travel the 14 South to the 5 you pass my house. Victorville to Orange County, that is crazy. We should hang sometime.

[Cyrk]

LOL... I get about 215 a tankful and that is squeezing it to the very last bit. Then again I have the S/C and a concrete leg that is attached to the go pedal.

[Ldub]

Cyrk,

Couldn't agree more...the loudpedal sucks petrol bigtime w/ s/c.

However, on a calm day on flat ground, (believe me, we have plenty round these here parts) I can sometimes squeeze 19-20 out of her w/ cc set about 70-75.

My $.02, Ldub

[migil]

I've had my VX since '01 and I've been consistently getting about 330 miles per tank using 87 octane gas. It normally takes a little over 300 miles before the gas light comes on steadily. 63K miles and still running strong.

My city/highway driving ratio have varied over these years. I'm convinced that being in Florida (A/C on most of year, no hills whatsoever around here), some minor upgrades (K&N stock filter, synthetic oil all around) and an average driving style have contributed to the acceptable (by VX standards) gas mileage I'm enjoying.

[morgan-tec]

One thing to keep in mind is that mpg will be effected by the elevation you live at, this is commonly forgotten. My Axiom has an onboard info center that tells me i get 17.5 avg mpg with a very heavy foot and my 22s. I did notice a solid 1.5-2 avg mpg increase with my intake kit, and another .5-1mpg with my exhaust. Even with the way i drive which is very agressivly i still get decent milage. Remember that my Axiom is quite a bit heavier than the VX but has the ecact same drive train. The biggest factors to good mpg are clean air filter, regular oil changes with quality stuff, and good gas. I have found the last one to be a big factor in my area, if you get the cheapest gas you can find from the "U pump it"you will get a noticable amount less mpg than with a quality gas such as Shell or Texaco.

[Ron Pfeiffer]

I noticed that I get about 290 miles to the tank (310 corrected for Nittos) in the winter, but can squeeze 310 (332) out in the summer. I live in northern VA, so the differences are noticable, but certainly not what I would call extreme.

Colder, denser air = more oxygen content per given volumer = more aggresive combustion?

My Yakima rack with full-sized spare costs me about 20 miles per tank. Interestingly enough, my rack WITHOUT the tire has the same penalty.

Ron

[engfant]

I maybe able to add to this. I am a former owner of a VX (and will be again in the near future as $550/month wasn't doing it for me :rolleyes: )

I now drive an 81 Olds Cutlas with 30K original miles (bought it with 17k)

NOW, over the past 18months I've also noticed that I am getting like 15MPG and this is after 3 tune ups.

I decided to do a little investigating. Has anyone ever thought that the gas stations are WATERING DOWN THEIR GAS???!?!?!?!?!?!

I can ONLY drive my car on 93 octane and anything lower causes EXTREME ENGINE PING. This has only started to happen and is MUCH MORE NOTICEABLE in a carborated engine.

I asked the dude over at the local Valvoline and he didn't DENY this is happening, just isn't in a position to start pointing fingers.

(ps. STOP HATING ON THAT VX. There are plenty of us out there that would LOVE to be back in theirs ;) )

[volume311]

Colder, denser air = more oxygen content per given volumer = more aggresive combustion?

Ron

Colder air is denser so yea better for combustion but because it is denser it is worse for aerodynamics. The tradeoff isn't the eaull so I don't know which one wins. :p

[xdfarrx]

I get 300-375 depending on driving style-

[Bulldoggie]

I decided to do a little investigating. Has anyone ever thought that the gas stations are WATERING DOWN THEIR GAS???!?!?!?!?!?!

I don't know about water, but they have been busted before for altering the electronic in the meters and I think they are doing it again! Three times I've gotten reciepts for more than the capacity of the tank and I didn't push it in.

[SPAZZ]

I purchased my VX in SanDiego April of 2001 where I was stationed in the MArine Corps from Sep 1995 to Oct 2003. Right after I purchased it I drove it 55mph for the break in period and then was kind of easy on it and accelerated slowly and went only 65 - 70 mph max till I reached a few thousand miles then I decided to drive aggresively. I still got 400 - 410 miles per tank. I drove it home to Colorado which is like 1,000 miles one way, drove another 1,000 miles while there over a month period and then drove it the 1,000 miles back to base.

California puts that detergent in your gas that burns cleaner emissions, but gums up your fuel system. So, the further away I got from Cali the detergent was worked out of the system with the nontainted gas. Also, in high altitudes I was able to use the available 85 octane gas and my mileage was boosted to almost 20mpg. I never was able to get better mileage than with the 95 Octane fuel even though I was driving up and down through the mountains. As soon as I got back to Cali and that crappy detergent gas started to gum things up my mileage would drop drastically to 15mpg. once I passed 12,000 miles on the Odometer it was all downhill from there. till rockbottom at 200miles per tank.

So, I was able to drive in Colorado's high elevation 400 Miles per tank and then go to driving SanDiego's sea level elevation at 200 MPT. That is all on a stock VX. That was when I started to mod for better performance. A unibody lexus weighs more than the VX and gets better mileage, how??? The Trooper gets better mileage and weighs more than the VX...is it the true 3.5 engine with 3.5 heads and not the VX's 3.2 engine with 3.5 ported heads even though the light weight???

Our VX should have a V8 and get the performance for the mileage that it gets and not poor mileage from a 4,000 pound vehicle with a V6. The Monteros have less horsepower and torque than the VX, weigh more, and they perform just as good on road(offroad the VX blows it away) how do you figure??? teh VX is the poorest financial investment in terms of automobiles, but the best mental personal investment in terms of offroad for me. maybe a Hemi would just about do it in the VX...get the horsepower for the mileage. I bet it would just about be the same off road and better on the highway for mileage.

[mbeach]

The Monteros have less horsepower and torque than the VX, weigh more, and they perform just as good on road(offroad the VX blows it away) how do you figure???

I agree with the VX needing a more powerful motor, but with more and more research I'm starting to accept that more CCs is not the way to go.
I'm assuming that you're referring to the body-on-frame Monteros, which have a very similar construction to the VX, and also displace 3.5L. They also get 17mpg, regardless of city/highway -I've worked on quite a few and if I could find a '99 SR, I wouldn't be driving a VX.
It really boils down to a weak engine in a heavy truck = poor mpg.

With appropriate gearing, tires and a diet, the VX could be a competitor in the milage events, with very little work done to the engine (just basic performance mods).
The fact is, most of us add things (like big tires, big stereos, racks, etc.) that KILL our gas mileage. Someone's sig says it best:
[I]The price you pay to be different[I]

It is my personal opinion that the single worst feature of the truck is the transmission. I can just feel this thing sucking up horsepower.
I think that if someone manages the 5 speed swap, we can expect 20+ mpg all day long.

[cascabel3]

I would have given anything for a 5 speed manual tranny on the VX. The one thing I didn't like about the VX was the lack of that option. Granted, in heavy traffic an automatic is better, but although I live in LA basin I manage to avoid traffic for the most part. Like MBeach stated, the tranny is a big part of the waste.

Spazz also answered one of my long sought curiosities; when I road-tripped in my '91 Trooper I noticed that I got better mileage once out of California. When I drove through Colorado where I spent a bit of time above 8000 ft, My mileage was insane. At times I though my gauge was broken, the needle just wouldn't budge. I deduced back then that this was due to following causes:

At higher altitudes electronic ignition will lean the fuel/air mixture to compensate for thinner air, the reason Jets fly as high as they do (leaner mix, less friction and catching certain currents) and the fact that on these Colorado mountain roads my average speed was ~45MPH. Now I can add Spazz' California fuel factor and complete my theory.

[Numba1goalie]

So basically, out of all of this, there really is no cure to making our milage better?

For the most part with California residents that is?

[Ldub]

Just drive down hill,with the wind all the time. You almost never get where you wanted to go, but you get to see new places! :p :p :p :confused:

[VehiGAZ]

Actually, the VX's automatic tranny is not a problem like you might think, because it runs full-lockup in all but first gear, so the power loss due to an oil coupling in the drivetrain is just not there. The fact is that the VX is a very heavy vehicle (for its size), with full-time 4WD, a big frontal area, a high-drag body, and an engine that gets a lot of torque out of a gallon of gas. You're not going to make a 25 mpg gas-sipper out of that.

I've gotten as low as 13.9 mpg with my Yakima cargo box in the winter and as high as 18.2 in the summer with no box. (The box costs me about 1 mpg whatever the season) Winter air is denser, but colder, which I think is what reduces mileage in the winter on ALL vehicles.

Speed and the amount of stop-and-go is the big difference from what I can tell. I push 80 mph on the highway, and I can tell the engine needs a lot more pedal to keep the pace. When I run long distances on back roads between 45 and 65 mph, I get the best mileage (a hair over 18 mpg). It drops at least 1 mpg when I'm running on the highway at 80. On the other hand, my 20-mile drive to work at 40-50 mph on back roads with several stop signs and lights makes my mileage drop to about 16.5 or so. Same speed range, but more stopping-and-going make the difference.

Another thing I noticed on my old Prelude is that a change in tires made a big difference in the mileage. With the original tires (Bridgestone all-season sport tires) I got as much as 26 mpg highway. When I swithed to Avon three-season performance tires, it dropped to about 23.5 mpg. The mileage you get in the stock car can change with almost any mod. All the little factors play together to determine your mileage. Change any of them, and you may change your mileage.

Locale and types of gas make a huge difference, too. The gas you get in one city will not be the same formulation that you get in the next - even if it's the same grade and the same company!! In fact, the landscape of gas formulations is wildly complex, and it's a principle cause of the generally high price of gas. Refineries have to make literally dozens of different formulations of the same octane grade to supply each and every county with the type of gas they think will be best for their environment. Car & Driver did a great article on this a few yeas ago. It's a ridiculous situation, really.

If you want cheaper gas, tell your state congressman to reduce the number of formulations that localities have to pick from.

Ok, time to get off the soap box and get to work...

[Numba1goalie]

Awesome information.

So basically all we can do is fold our arms and like it!

[VehiGAZ]

That was the sub-text, yes. ;-)

I don't think any of us bought our VXs without knowing the fuel economy situation. But significant decreases in economy (other than by our own zany mods) is a perfectly legitimate gripe.

[Chopper]

Sorry, I'm the exception. I've always gotten 17 or 18 here in very flat Fla.. Mobil 1 and Green Grease all around with fanatical matainance. True- when I blast around, it'll drop to 11.

[deermagnet]

The lowest mpg I've gotten is 17.5. I always run stock size tires, so my odometer is apparently correct. Last summer I checked my mileage with three fills in a row on stock spark plugs with 77K miles and got 19.73-19.97. This week with new plugs after 9K miles I filled up and drove 304.6 miles. It took 15.44 gallons to refill, so that comes to 19.73 mpg. I guess it could be the summer fuel mix, but whatever it is, I like it.

Mark Griffin http://www.wtv-zone.com/markg/mags/mags2/drive.gif

[Jolly Roger VX'er]

When I went to the Vermont VX-Plore meet from PA I was running my VX with cruise at 65 most of the way traveling interstate 90 with 31" Bridgestone Revo AT's(@40psi with 44psi max) and the SC/CF intake and got 22.6 mpg (no adj. for tire size) on the way to the meet and busted 23 mpg (no adj. for tire size) on the way back. I did swap out my fuel pressure regulator a few weeks back.

Spazz...I think you should change out your fuel pressure regulator...my VX got worse mileage over time and even started having starting issues when hot (i.e. stopping for gas it would take 2-3 times to restart)...all of this was cured when I changed out my fuel pressure regulator.

[SPAZZ]

Fuel Pressure Regulator???

[Jolly Roger VX'er]

Fuel Pressure Regulator???

oops..sorry...yes thats what I meant..."fuel pressure regulator".

http://www.vehicross.info/gallery/showphoto.php?photo=6263&sort=&page=2&sortby=&sorttime=&sortdir=

[SPAZZ]

how easy to change myself??

[Jolly Roger VX'er]

how easy to change myself??

I pretty sure I paid about $48 and ordered from my dealer. You can also buy what my dealer called a rebuild kit for $12 but I recommend buying the whole unit as you see it in the pic posted in my last post.

I have the SC so I only had to remove the one fuel rail with 3 injectors..you being stock I can't remember if you have to remove the whole fuel rail or not...somebody please chime in! You should begin by pulling off the cosmetic cover that has the 3.5 DOHC on it and you'll see your fuel rail with fuel pressure regulator attached to the rear of the driver side where fuel line hooks to bottom of it. Ask Tone if nobody chimes in but my job only took about an hour to do...not hard. I had to replace two injector o-rings too because they were damaged either when installed or when I pulled them out.
The new part has a new lock ring too in case you don't want to reuse the old one. If you can do all that CV front-end stuff you do spazz, this is a piece of cake......I purged fuel pressure too just like when you change fuel filter so you don't have gas spraying all over!

[SPAZZ]

$48???? huh, what??? Isuzu dealers I talk to want like $200 ..even St Charles and the auto parts stores want like $150 to $170 for the "Fuel Pressure Regulator.

Where do you shop?

[Jolly Roger VX'er]

$48???? huh, what??? Isuzu dealers I talk to want like $200 ..even St Charles and the auto parts stores want like $150 to $170 for the "Fuel Pressure Regulator.

Where do you shop?

I bought mine at the new ISUZU dealer here in Erie, PA and I know I paid with tax like $52:

AUTO EXPRESS---ISUZU
10320 WATTSBURG RD
ERIE, PA 16509
(814) 825-4747

Also found the fuel pressure regulator at this website for $52:

http://www.drivewerks.com/cgi-bin/ppexpress/ppe_drivewerks.cgi?command=show_part_page&YEAR=2000&MAKE=IS&MODEL=VEH--001&Category=C&esc_part=Fuel+Pressure+Regulator