2006 v8 4x4 with bad mpg

[KingPrat]

Honestly? You're not gonna get that much more out of the V8, especially with what sounds like more city driving than highway. I put 55k miles on mine and averaged just over 17mpg with a LOT of highway.

Worst tank was 12-13. Best was 21 (only once).


My computer was always off. If you want to feel better about it, calculate it by hand. I was always +1.5 on the low end and -1.5 on the high end compared to the display.

:banana:

 

[AuSeeker]

This is something interesting I figured out by accident.

Driving *slightly* more aggressively will give a bit better MPG than granny-pedaling it. For a few days at work I had to do a lot of running around town. I topped off the tank and did what I had to do, then topped off again when I was done. (Made it easier for expenses this way) I use the Fuelly app to track MPG, and I've observed that the dash computer is optimistic by 2mpg.

I noticed that by putting a little more mustard on it, my MPG was actually up about 2 mpg than the usual. I'm guessing this was because I was spending less time in the lower gears.

Makes sense to me... Consider this example with data harvested from what I remember while driving and thinking about other things and a highly scientific image to illustrate:

You're on a 45mph road, 50 miles long, with stop signs at evenly spaced intervals.

When driving granny-like, the engine is running slower, but it's spending more time covering distance in the lower gears. So the 2000 engine RPMs are being spent less efficiently until it works its way up to 5th gear.

When you accelerate a little harder, you get up to 45 mph quicker and the engine spends less time at higher RPM's with lesser output, and spends more time in 5th gear at a constant speed.

Just my theory with absolutely no math or science to go with it. One thing that always baffles me is the whole "You get better MPG on the highway going 45mph than 90mph" because I keep thinking "but the engine is running twice as long, so...."

Dutifully Submitted,
KC Murphy: Overthinking everything since 1972

Well I'm one of the ones that uses the "granny" driving to get what seems to be better MPGs, I always hand calculate my MPGs at every fill up, so I will be trying your theory to see if I get the same results, if I do it will blow the theory that has been touted for years and years of "Jack Rabbit" starts gets you bad MPG!!

I will report back in about a month or two, I will do 2 to 3 tankfuls to see the results.

 

[Montego Murph]

if I do it will blow the theory that has been touted for years and years of "Jack Rabbit" starts gets you bad MPG!!

I will report back in about a month or two, I will do 2 to 3 tankfuls to see the results.

Well, before you do that... I'm not talking about a full throttle launch... How can I describe what I've been doing... Smooth Steady and Powerful? Basically, not hard enough to annoy my passengers. There's nothing worse than being in a car with someone who treats the pedals like on/off switches.

 

[AuSeeker]

Well, before you do that... I'm not talking about a full throttle launch... How can I describe what I've been doing... Smooth Steady and Powerful? Basically, not hard enough to annoy my passengers. There's nothing worse than being in a car with someone who treats the pedals like on/off switches.

I'm not going to turn my 4Runner into a drag racer, just accelerate more quickly, I normally try and make my shift points at between 1500 and 2500 rpms, so I'm going to up that to around 2500 to 3500 rpms.

 

[94toy22re]

I have a 10 mile city work commute and i average 17, i keep it under 2000rpm!

 

[AuSeeker]

I have a 10 mile city work commute and i average 17, i keep it under 2000rpm!

When you say 17, is that the readout or manually calculated?

 

[94toy22re]

When you say 17, is that the readout or manually calculated?

Hand calculated

 

[Jasonredwood]

Still trying to figure out this engine shudder I have and hoping that helps with the MPG. No response on the the thread I started.
http://www.toyota-4runner.org/4th-gen-t4rs/239221-slight-engine-vibration-occasion-v8.html
"To get the rig caught up on maintenance I have done timing belt and water pump, new iridium plugs, new air filter, cleaned MAF, oil and filter, new PCV valve, sea foamed through pcv valve and put some Lucas fuel cleaner in the the last tank.
What else do you all suggest looking at?"

My onboard comp seems pretty accurate to my hand calculations, maybe off by half a MPG give or take.

I'm still averaging around 11-12 city and 14-15 freeway. Took it on a 700 mile trip this last weekend to go camping. 2 adults, 1 three year old and, 85lbs of dogs and all our gear. interior loaded up and the roof packed up well. A steady 14mpg after mixing all the freeway miles with the offroad miles.

 

[r_alexander]

ditto for my '08 v8 ltd 4wd

full k&n intake, new plugs, injector cleaner, oil/filter change, new front caliper, grease all fittings underneath, 265/65/18s & still consistent at 17.5mpg. Winter blend knocks that down ~1mpg.

 

[Phils4th]

Your mpg isn't all that bad. It's not going to get better unless you change to street tires and slam it, shave off hundreds of pounds, drive smart, or invest hundreds in parts.

The engine vibration can be damn near anything. We're going to need some more info. Any rpm drop or rise? A/c on? This is the usual cause. You can also inspect your engine mounts, loose or rotted mounts cause normal vibrations to feel like a problem. If it could affect the engine strong enough, it should be setting off a CEL. Check the balancer on the crankshaft, it can rot. Also check the balancer-pulley bolts and how it is operating when running , if it's been worked on and someone leaves a bolt off, that can also affect balance. If there is anything else that could be crazy that is ignition related like a bad coil, bad leads, bad crank signal, you need to take it to a shop that can use an oscilloscope and leakdown test.

 

[AuSeeker]

This is something interesting I figured out by accident.

Driving *slightly* more aggressively will give a bit better MPG than granny-pedaling it. For a few days at work I had to do a lot of running around town. I topped off the tank and did what I had to do, then topped off again when I was done. (Made it easier for expenses this way) I use the Fuelly app to track MPG, and I've observed that the dash computer is optimistic by 2mpg.

I noticed that by putting a little more mustard on it, my MPG was actually up about 2 mpg than the usual. I'm guessing this was because I was spending less time in the lower gears.

Makes sense to me... Consider this example with data harvested from what I remember while driving and thinking about other things and a highly scientific image to illustrate:

You're on a 45mph road, 50 miles long, with stop signs at evenly spaced intervals.

When driving granny-like, the engine is running slower, but it's spending more time covering distance in the lower gears. So the 2000 engine RPMs are being spent less efficiently until it works its way up to 5th gear.

When you accelerate a little harder, you get up to 45 mph quicker and the engine spends less time at higher RPM's with lesser output, and spends more time in 5th gear at a constant speed.

Just my theory with absolutely no math or science to go with it. One thing that always baffles me is the whole "You get better MPG on the highway going 45mph than 90mph" because I keep thinking "but the engine is running twice as long, so...."

Dutifully Submitted,
KC Murphy: Overthinking everything since 1972

Well I'm one of the ones that uses the "granny" driving to get what seems to be better MPGs, I always hand calculate my MPGs at every fill up, so I will be trying your theory to see if I get the same results, if I do it will blow the theory that has been touted for years and years of "Jack Rabbit" starts gets you bad MPG!!

I will report back in about a month or two, I will do 2 to 3 tankfuls to see the results.

Well for myself I disproved this theory with the first tank of gas, I usually try and keep my shift points between 1500 RPMs and 2000 RPMs with the occasional 2200 RPMs and get about 18+ MPG manually calculated, mostly urban to city driving averaging around 30 MPH on the display, I have been increasing my shift points to somewhere between basically 2000 RPMs and 2500 RPMs with a few times up to 3000 RPMs, and a couple of times up to 3500 RPMs to get out into traffic and the average MPH are still around 30 MPH on the display, and I just filled up and hand calculated the MPG, I lost 1.75 MPG by increasing the RPM shift points driving the same routes as the last 3 tankfuls, so I will be going back to my "granny driving" habits.

 

[Jasonredwood]

Your mpg isn't all that bad. It's not going to get better unless you change to street tires and slam it, shave off hundreds of pounds, drive smart, or invest hundreds in parts.

The engine vibration can be damn near anything. We're going to need some more info. Any rpm drop or rise? A/c on? This is the usual cause. You can also inspect your engine mounts, loose or rotted mounts cause normal vibrations to feel like a problem. If it could affect the engine strong enough, it should be setting off a CEL. Check the balancer on the crankshaft, it can rot. Also check the balancer-pulley bolts and how it is operating when running , if it's been worked on and someone leaves a bolt off, that can also affect balance. If there is anything else that could be crazy that is ignition related like a bad coil, bad leads, bad crank signal, you need to take it to a shop that can use an oscilloscope and leakdown test.

No RPM drop or rise. DOesnt seem to matter if the A/C is on or off. GOing to check out the engine mounts as suggested on expo.

I also found this thread which makes me feel like its not an uncommon issue on these engines.
4.7L Engine Vibration at Idle Only - Toyota Tundra Forums : Tundra Solutions Forum
Found a few other posts online that sound similar.

 

[ssmd]

I have a post about CEL codes that led me to replace my fuel pump assembly. I just came back from a 1,400 mile road trip and noticed a significant increase in mileage even with a half full trunk and a 1000 lbs trailer in tow. Got around 18mpg on fill ups going 70-85mph. I hit 21-22 mpgs doing a stretch going 60-65mph. (mpg is from the cars computer)

As my fuel pump was getting weaker the mpgs dropped eventually the pump got so bad it threw P0171 & P0174 lean codes.

I suggest checking the fuel pressure and fuel trims to make sure everything is to spec.

To chase down the cause of the CEL I basically changed all the 02/AF sensors, MAF, cleaned the TB and seafoamed the engine a few times. Lastly I replaced the pump which fixed the whole issue and gave me back some mpgs. I was getting around 13mpg city and 15mpg highway with the CEL on.

I just did the fix before this trip where i towed the trailer the entire time so I'll have to wait to this weekend when I head to Delaware to get some highway mpg numbers without a trailer.

Peace.