Consider me impressed.. 24 MPG!

19963.4lsr5 said:
The checks and balances is the O2 sensor before the CAT. (The closed loop operation)

All the sensors (including TPS) input their data to the PCM/ECU. Based on those inputs the ECU picks a fuel map for those operating conditions. And in a perfect world you would have a 0 in the STFT and a 0 in the LTFT.

But the world isn't perfect so the O2 sensor reads the oxygen content of the exhaust and tweaks the fuel trims. That tweaking of the fuel trim shows up on your STFT (short term fuel trim) and LTFT (long term fuel trim). And it actually looks like this trim wise. LTFT.STFT so if your LTFT is near zero than its picked the proper map based on current inputs. The LTFT number tells you the overall health of the engine and fuel management system.

So if any sensor is off the O2 sensor will detect the richer or leaner mixture and act accordingly by adding or removing fuel. One check I do often is look at the ECT and IAT temp and make sure they are very close to each other as well as reading current ambient temp before a cold start where the vehicle has sat at least 8 hours.
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I also thought of the O2 sensor as performing the checks and balances on all the other sensors, to close the loop. So that should compensate for any of the other upstream sensors and actuators being out of whack.

I guess the underlying assumption in this is that the O2 sensor itself is working properly, and if it's not, then the ECU will throw a code (?).

I'm also curious about the comparison between ECT, IAT, and ambient temps that you do - do you ever see a significant discrepancy, and if so, what then?
 
While I'm not willing to trust MPG claims after just 1 fill-up, I will attest that it IS possible to get close to that amount (at least on a stock 2wd Auto with the V6).

I went through 5 or 6 tanks a few months back, and averaged 23.5 MPGs, hand calculated, with gas stations all over the city. I babied it the entire time. I slowly got up to the speed limit, then set the cruise control. I never went over 65mph / 2000rpm. I did not tail anyone or ride the brakes at all. Just your basic, safe, boring driving tips.

I found that to be boring, so I stopped for the most part. I still don't tail people, or speed all that often, but getting up to speed slowly like that is just excruciating. I still hover around 19-21 on average, though.
 
I use the same pump and use the slowest automatic fill setting to keep things the same.

The engine and throttle body temp test is just a simple test on occasion to make sure the sensors are performing correctly. If one is beyond 10 degrees of ambient after sitting overnight it gets replaced.


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If you guys want good mileage, put on some p-metric highway tires and keep the speeds down. Sorry, there goes your off road capabilities.

I have over 200k miles of records when my dad owned my 4Runner (2WD V6 auto with 225/75-15 tires) and it generally got 24-26mpg over that whole time. That's lots of commutes (~20 miles each way) and long trips at 65-67 mph.

Now with 4WD and 265/70-17 AT tires but traveling the same speed, it gets ~21 on the highway. Most fill ups are 16-18 now since I have such a short commute.

-Charlie
 
I get 23 in the warmer months commuting to work on 2 lane rural roads. It's a 32 mile drive too and from work. Winter I'm getting 18mpg tank average with a combined local and work driving.

Be carefull what you reveal mpg wise. There are plenty of members that will do everything possible to try and debunk your mpg claims.


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I did a fair amount of data-logging in cold weather, not with the 4Runner, and consistently saw somewhat noteworthy power gains compared to much warmer temperatures. I would not be surprised to see the inverse for fuel efficiency.

Cold, dry air, lower elevations = mo power. Fond memories of waking-up early, just to drive some canyon roads...
 
TonyB66 said:
I did a fair amount of data-logging in cold weather, not with the 4Runner, and consistently saw somewhat noteworthy power gains compared to much warmer temperatures. I would not be surprised to see the inverse for fuel efficiency.



Cold, dry air, lower elevations = mo power. Fond memories of waking-up early, just to drive some canyon roads...
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I call those days "good air days". When the barometer is 30+ and I hear the turbo on my Cummins zinging away it's all good. Those same days at the drag strip are welcome. A barometer of 30.20 or higher and you don't feel the extra power at the pedal or in my case the throttle grip of my 98 ZX9 means your not in tune with your vehicle.


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Well for what it's worth, I concluded that the Torque Pro avg mpg data is useless. Perhaps it can be recalibrated (I found some indications that it's possible), but certainly out of the box it is of no use to me.

I just drove 500 miles at mostly freeway speed, and calculated that I am averaging about 16 mpg with the new C rated BFG's (which apparently more than offset whatever benefit I got from cleaning the MAF :rolleyes:). Yet my Torque Pro was happy to tell me that my average mpg was 21. So ignore everything I posted above regarding Torque Pro values.
 
IBallEngineer said:
Yeah I'm way past skeptical, I'm an unbeliever. I have two 4runners, one is a 3RZ, and a 96 Tacoma 2wd with a 3.4 and there is no way any of them gets 24MPG. The 3RZ once saw almost 23MPG, but that was with little itty bitty tires and me really trying to get good fuel economy. Just not normal. As soon as I put a decent size tire I could never get over 19. V6? just no way possible. And one 450 mile trip is not a quality sample. I'd get 18 in my 3.4 on the highway, then 15 the next tank with mostly street driving. I average out at 16.3, and I check it every week.
:blah:
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I got 21.8 MPG on a road trip to Oregon once and only once. My supercharger LOVED 93 octane, it ran so good even at elevation. It was 100% highway driving at 50ish MPH so stayed in OD but minimized air drag. Basically it was the perfect scenario possible, will never happen again. Stock sized tires, no lift.

I haven't logged for a little while, but here's what I had going for a bit (doesn't have the Oregon trip on it though...): http://www.fuelly.com/car/toyota/4runner/1998/gamefreakgc/330715
 
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TonyB66 said:
I did a fair amount of data-logging in cold weather, not with the 4Runner, and consistently saw somewhat noteworthy power gains compared to much warmer temperatures. I would not be surprised to see the inverse for fuel efficiency.

Cold, dry air, lower elevations = mo power. Fond memories of waking-up early, just to drive some canyon roads...
Click to expand...

Here in CA we have two different fuel blends: summer and winter. You'll notice a steep drop off in MPG's in November when the pumps switch to the winter blend. Also, last summer they added more ethanol to our fuel and MPG's took a hit for older vehicles like 4Runners that are not made to use ethanol.

Cold weather = denser intake charge = more power. That's why it's good to dyno your vehicle in the mornings in the summer, once the temp starts to warm you lose power.
 
Hey everyone!

It has been awhile since I updated this post so here is an update:

Still running the Trail finder all terrain 265/75r16s (32 inch) p rated tires from Discount Tire.

My daily driving habit is to and from work and around town which averages me around 15 mpg, but I am consistently driving 2 miles to work, turning car off and going back home 2 miles. This starting and stopping attributes to the dismal city MPG which is expected.

However! Every time I go out of town, I fill up before, reset my trip odometer and then when I get to my destination I immediately stop and get gas and hand calculate my mileage. I always take into consideration the up sizing of tire circumference VS what my speedometer is calibrated for. Remember my truck is calibrated for the stock 15 inch wheels and tires. Every single trip, I average 22-24 MPGs purely on the highway at 65-72 MPH.

This I believe is due to a well maintained rig with passenger rated all terrain 32s. If I had LT or E rated tires, I imagine I would be getting a lot less. I also do not have a lead foot when I drive, as I try to stay consistent with the throttle.

I hope this update helps someone else realize that my first claim was not a fluke.

Stay safe out there!

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TejasRunner01 said:
This I believe is due to a well maintained rig with passenger rated all terrain 32s. If I had LT or E rated tires, I imagine I would be getting a lot less. I also do not have a lead foot when I drive, as I try to stay consistent with the throttle.
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I went from a 15" wheel, 2WD V6 auto that got ~24mpg highway, converted it to 4WD, regeared (4.10's), 32" K02's, plate bumper and heavy skids... and only dropped to ~22mpg highway.

A good running rig driven conservatively can still get "good" mileage.

-Charlie
 
Hey friend. You are not getting 22/24 mpg for a tank average.

And no 31.5" (they are not 32") tires do not equal getting 6 mpg greater than factory spec. The larger factory tires were 31" so extra 0.5" is really not a significant factor.

Yes some people in some situations on one leg of a trip have gotten above 20. But no one is actually getting 24 mpg on average.

The factory spec is around 15 city / 18 hwy. 24 mpg is 6 above spec. That is 33% above spec. Japanese engineers at Toyota are not total idiots. There are actually really good and didn't get it wrong.

Personally I still believe folks are as always failing to actually calculate mpg correctly.

How to do it correctly:
* Fill your tank. Don't top off.
* Mark mileage.
* Drive till talk empty
* Fill tank
* Mark mileage. Subtract.
* Divide for mpg.
* If tire correction is needed then factor that in.

Don't use an app. Do not use a scanguage.

.
 
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BrianSD_42 said:
Hey friend. You are not getting 22/24 mpg for a tank average.

And no 31.5" (they are not 32") tires do not equal getting 6 mpg greater than factory spec. The larger factory tires were 31" so extra 0.5" is really not a significant factor.

Yes some people in some situations on one leg of a trip have gotten above 20. But no one is actually getting 24 mpg on average.

The factory spec is around 15 city / 18 hwy. 24 mpg is 6 above spec. That is 33% above spec. Japanese engineers at Toyota are not total idiots. There are actually really good and didn't get it wrong.

Personally I still believe folks are as always failing to actually calculate mpg correctly.

How to do it correctly:
* Fill your tank. Don't top off.
* Mark mileage.
* Drive till talk empty
* Fill tank
* Mark mileage. Subtract.
* Divide for mpg.
* If tire correction is needed then factor that in.

Don't use an app. Do not use a scanguage.

.
Click to expand...

Well I'm not trying to start any arguments, and for what it is worth on long trips where the entire tank of gas is on the highway, I am still getting 22-24 mpg. Many have reported getting greater than stock MPG numbers.

I actually use that exact calculation sequence with a correction of 11.7% because my rig came with 225/75r15s and I run 265/75r16s. I don't ever use an app and I don't have a scanguage. Thanks for the reply.:peace:
 
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I have found that 60 mph seems to be the magic number on the interstate. On a 6 hour trip, I once got 23.5 mpg by setting cruise control on 60.

Fuel economy starts going downhill real fast after 65 mph with these things. 70 or more, and I'm very lucky to see 19 mpg.

I typically get 18-19 mpg around town.
 
aerobat66 said:
I have found that 60 mph seems to be the magic number on the interstate. On a 6 hour trip, I once got 23.5 mpg by setting cruise control on 60.

Fuel economy starts going downhill real fast after 65 mph with these things. 70 or more, and I'm very lucky to see 19 mpg.

I typically get 18-19 mpg around town.
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Oh wow. That's with every car, or this truck specifically? Meaning, over 70, 4 mpg less? This makes sense. I think I got 23 mpg highway, when I was going slower.
 
Jason B said:
Oh wow. That's with every car, or this truck specifically? Meaning, over 70, 4 mpg less? This makes sense. I think I got 23 mpg highway, when I was going slower.
Click to expand...

It would all vary, according to the vehicle. The aerodynamic drag increases, probably not linearly, with speed. Some lightweight vehicles with good aerodynamics (the T4R is neither) get just great fuel economy at 70-80 mpg. Hell, I got 32.5 mpg in my old Miata, running 80 mph for 3 hours, with the top down.
 
Cool. Oh, and how does going to say 40 PSI on the tires help, vs say 34 psi. Bet that would give a nice bump.
 
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