Another Gas Mileage Question (1 Viewer)

[sigchuck]

The gas mileage in my 2006 100 series has been getting progressively worse over the past couple of years. My commute is relatively short and all in town, but over the past few months I've averaged 10.4 mpg. I can get around 10.6 if I am very mindful of my right foot.

The truck has 130,000 miles on it, and I do perform regular maintenance. I plan to clean the throttle body and MAF (last done approximately 15,000 miles ago, which was also 2 years ago).

Any other thoughts as to what could be causing the terrible mileage? Around 2.5 years ago when my I started my intown commutes, I was around 12 mpg.

Thanks in advance!

 

[M3gilly]

I'd check: tire pressures, fuel filter, spark plugs/wires, brakes (make sure you don't have a pad dragging on the rotor), intake filter?

 

[oakback]

I'll piggy back off this question since I'm having a similar problem. One of my O2 sensors is bad, could that cause a change in mileage?

 

[PDPerry]

... One of my O2 sensors is bad, could that cause a change in mileage?

Very much so...

 

[tlcruiserman]

Hello, So I have seen this with the 100 series as well, and although I don't know for sure, I have some stuff I have done to back this up. This is assuming it is nothing else that was mentioned about, i have seen that as this 4.7 V8 get miles on them (100+) depending on how well they were maintained they will start to drop off on mileage, and I think that is because as they get older, they are still very sound, however they produce less power, and hence a little more throttle is needed for the same driving style. I have rebuild a few of these motors and mileage certainly improves after the rebuild. It would be great if we could get some of these 100's on a 4 wheel dyno and see what power they are producing to prove this out.

Thanks,

Michael

 

[jhanley]

Honestly, for a "short and all in town commute" 10.6 mpg doesn't sound obtuse. That's what mine gets around town, 15 highway.

If anyone on MUD gets more than 11 from stop-light-to-stop-light, please chime in. I even did the race-car weight savings mods, removed running boards and third-row.

 

[sigchuck]

I do plan to change the air intake filter when I clean the MAF and throttle body. I am considering the fuel filter, O2 sensors, and plugs as they're all original to the vehicle. Think there will be any pickup in mileage?

The truck seems to be performing fine (no rough idle, CEL, etc.), it's just poor mileage. Thanks!

 

[jhanley]

I do plan to change the air intake filter when I clean the MAF and throttle body. I am considering the fuel filter, O2 sensors, and plugs as they're all original to the vehicle. Think there will be any pickup in mileage?

The truck seems to be performing fine (no rough idle, CEL, etc.), it's just poor mileage. Thanks!

I don't think it's performing badly - what was your MPG before? Again, almost 11 mpg around town is normal. My rig is totally baselined, new 02 sensors this year, cleaned MAF and throttle body, K&N intake, I even slightly over-inflate my tires.

 

[stough77]

Honestly, for a "short and all in town commute" 10.6 mpg doesn't sound obtuse. That's what mine gets around town, 15 highway.

If anyone on MUD gets more than 11 from stop-light-to-stop-light, please chime in. I even did the race-car weight savings mods, removed running boards and third-row.

I completely agree with this statement. My averages vary by 1mpg roughly but essentially they're same.

 

[jblatl]

I am getting 12-13 mpg in my 1999 LX470 this is all in town stop and go traffic.

I get 13-14 mpg in my 2011 Land Cruiser as well, not surprised.

Trucks are both stock...

Seems normal

 

[re_guderian]

The gas mileage in my 2006 100 series has been getting progressively worse over the past couple of years. My commute is relatively short and all in town, but over the past few months I've averaged 10.4 mpg. I can get around 10.6 if I am very mindful of my right foot.

The truck has 130,000 miles on it, and I do perform regular maintenance. I plan to clean the throttle body and MAF (last done approximately 15,000 miles ago, which was also 2 years ago).

Any other thoughts as to what could be causing the terrible mileage? Around 2.5 years ago when my I started my intown commutes, I was around 12 mpg.

Thanks in advance!

By your averages, you sound like you track it every tank. Publish up all your tanks. Not saying you are, but most people tend to exaggerate their MPG's at both extremes, and memory is easily biased towards the present. I'm between 11-13 all year long, unless I'm towing, or off-road, then it's straight-up abysmal. I don't take this one on as many long road trips, usually take my wife's '04 LC. This is unadjusted, straight odometer miles travelled / gallons per fill up (ACAR app). I run 295/75/16's, and a mild lift. 255K miles. AC runs pretty much all year. Daily commute is ~15 miles each way of surface streets with typical 45 mph speed limits, and an average of 1-3 stop lights per mile.

and dang, I am NOT getting out and burning full tanks of fuel on the trail enough. I need to burn my fair share of the earth's petroleum, before it runs out... On that note, have you ever calculated how much (gal and $) you've spent on cruiser gas? 250K miles at 12 MPG = 20,833 gallons of gas.

 

[re_guderian]

I thought that all the 100 series were on the old EPA sticker rules, which allowed hand-built/tuned engines, and highway with AC off, etc. and STILL, the window sticker on these was 11 MPG city, 15 hwy, 13 overall, no?

 

[Spike555]

I average 14.5 daily combined, surface streets on my way into work, highway home. I also use a app to track my MPG.
One thing I have noticed though, thanks to the app, my MPG varies depending on where I get fuel.

Yes new spark plugs will help, better combustion of the fuel will increase MPG.
The obvious like everyone else already said, air filter, tire PSI, stuck brake caliper.
It is summer, a/c on will have a effect too.

 

[ton504]

10.6mpg is pretty bad if this is a stock 5spd truck. Theres a lot of variables but I would check tire pressure first. Maybe do a visual to see if theres a large amount of toe out/in on the front alignment(inner tie rods get old and sloppy).

My supercharged 4spd LX470 with 295/75/16s gets 11-13 mpg on 93. My daily commute is usually 12 miles, stop and go, all below 50 mph. I like to hear the supercharger wine so I'm usually giving it a decent amount of throttle to get her up to speed. I'm not very mindful of my right foot.

 

[FxFormat]

I get 12mpg around town, 14 hwy, but i'm also lifted 1.25" and rolling on 33" tires on 18" rims. The rim/tire combo weighs 100lbs per corner, it's backbreaking when i rotate tires.

 

[sigchuck]

Thanks, guys. Sounds like I may be within normal range. There are very few sections on my commute where I'm ever above 30mph. The "average speed" per the Trip Info in the navigation is usually low 20s for every trip I take. Lots of stop and go and a good amount of idling.

The navigation trip info tab is also my source for the mpg data, and I've double checked it with manual calculations. I very rarely ever use the truck for anything besides my commute, so I generally fill up every 12-14 days, and have been consistently getting in the 10s for the past several months - probably close to a year.

I'll double check tires, but I do have the tire pressure sensors that seem to work quite well (spare has a very slow leak).

I'll go ahead and replace o2 sensors, fuel filter, and plugs (good piece of mind even if no mileage pickup) and check for hanging calipers. I don't think it's the brakes as I just had the dealer replace the front rotors two months ago and mileage is same before and after.

Thanks again for everyone's input.

 

[geanes]

98 LX 4speed here with 160k running on 285/65/18 Nitto TerraGrapplers aired up to 42psi. Speedo was never recalibrated so my mpg would actually be a little better (not much) than what I'm calculating now (speedo off by 4.7 mph at 70 mph). 42 fuel ups since purchased in March (9k put on in that time). I've tracked everything thru Fuelly. Based in Austin, TX where traffic is, well, thick as mud and temperatures are hot. 54% City/46% Highway (large part of that hwy mileage was the 1800 mile round trip to Colorado, 700 mile round trip to South Padre). Average mpg is tracking at 13.2 mpg with a worst mpg of 11.2 and a best of 16.7. The 16.7 was done in Colorado with trail driving on 85 octane and road driving from Leadville to Rocky Mountain National to Nederland and finish in Boulder. Still can't fathom that mileage. But, my mpg in Colorado is easily 1-2mpg better even with the lower octane and hours of trail driving.

I typically refuel at 250 miles to make sure I don't damage the fuel pump. I don't drive in downtown traffic, but stop and go suburban traffic. My trips are also 15 miles minimum in one direction. I would imagine that if my trips were shorter and in greater congestion, my mileage would drop by 1-2 mpg. 10.6mpg doesn't seem terribly off if you're driving short distances.

@sigchuck ... One thing to check: you mentioned cleaning the MAF.....have you cleaned the Throttle Body? I ask because when I opened mine, it was caked up pretty good despite "routine" maintenance by the previous owner. I cleaned it thoroughly and my engine ran smoother and my mpg went from 12.6 to the now 13.2 I'm seeing today with no change in my driving.