4runner 2004 v8 - awful fuel consumption

Hello,
Having my 4runner 2004 v8 for almost 3 months.
Had the chance to refill the tank for several times, and now I can tell that my fuel consumption is 10mpg.
This is what I see on the computer, this is what I'm getting based on my calculations during refill.
All my rides are within the city, but still - this figure is really bad.
Ideas? Removing the catalytic converter will help in achieving some mpg?
Thanks!

 

Do you have a lot of weight added to it? Steel bumpers, winch, roof rack with spare on top, large heavy tires? I guess the cat could be the problem.

 

None of these.
Stock tires (265/65R17), no load, no add ons and I'm the only one inside the car.
Not even use the ac on regular basis.
Maybe the catalytic converter is dirty (although the car is pulling excellent)? Maybe the spark plugs?

 

The first thing I would check and clean is the Mass Airflow Sensor. If these get dirty or have something shorted across the sensor wires they will send incorrect voltage readings to the ECM and throw your fuel trims out of whack. I like to use CRC mass airflow sensor cleaner on these as it does a good job.
There other option is to take it to someone who has a diagnostic scanner and have them check out the modules to see if anything is off.
Good luck with it as it should do better mpg’s than that. I have a 2004 with a V6 that averages about 17 with combo country and city driving.
I also have a V8 Tundra that averages about the same mpg as the V6 4Runner.

 

May also want to take a look at the throttle body, I recently cleaned mine and noticed an improvement in acceleration and mpg. I have an 06 V8 with about 200k and average around 18-19mpg around 16-17 before the cleaning. Past that, an expert may need to chime in

 

Just so you know....
I had a 2011 Tacoma with mileage problems after replacing the spark plugs. When I installed new Denso plugs, my mileage DROPPED by 3 MPG. I then switched to NGK and recovered all lost mileage. Changes were immediate and obvious, as I had a ScanGauge on the vehicle. Don’t know if this is an issue with the 4-Runner or not, but I will not risk using Denso again. Just saying...

 

Thanks roymm!
Meanwhile my mileage increased to 13ish.. For me it's significantly better! Hope to scratch the 15ish one day.

 

Get it on a scan tool that can be read while running. My guess is that a sensor (02, mass air flow, etc) or the ERG system needs to be cleaned or replaced. I bet if you looked at the plugs they would show too much fuel is getting in.

 

As is evident in the preceding posts, virtually any component (when not functioning properly) can contribute to poor gas mileage. From ignition to emission control, even motor oil and tire pressure. Add up a mile here and a mile there and the result can be significant. While 10 MPG is outrageous and is likely the result of a specific area of “failure or malfunction”, it all adds up. Once you identify the specific major contributor (and address it) make sure to adopt a wholistic view of vehicle maintenance. Your Yota will be glad you did.

 

I’m watching this with heavy breathing as I’m in the same unexplained boat. Spark plugs were recently changed by Toyota, and no change in results. Used to get approx 315 miles in range, now showing 240 miles in range on full tank. Going to try throttle body and/or MAF sensor cleaning.

Will do one at a time so I can be sure to isolate the correct fix and report my findings.

 

Please keep us posted after the sensor cleaning.
Mine is still DISASTER!

 

Best advice at this point is get an obd2 reader and look at live data to see what the engine is doing. Could be a vacuum leak. Could be running lean. Could need a valve job. There are a few reasons an engine will run ok while burning more fuel, you need to see live data in order to narrow it down. You can get a dongle that pairs to your phone for about $15 on ebay.

 

Anytime I see a fuel consumption problem thread, I have to chime in with a potential stuck caliper.
I've had two in 6 years, and both times noticeably reduced fuel consumption was the first clue that something was 'up'.

After you drive it a bit, park it and just walk around the car and stick your hand near the brake pad for each tire.
If one is Noticably Warmer than the other three, you may have found your problem.

 

Great point! Also don’t reuse those stainless shims that lay in between the pad and piston. It is not needed and will create a gap issue...Just something I picked up after doing a brake job seems there was a clearance issue.

 

Did you every find the issue? I have the exact same problem and I'm in the middle of trying to figure out what it could be.

 

Didn't figure out any solution.
Currently my average consumption is about 12 miles per gallon.
I used CRC 05078, doing maintenance every 3,000 miles (oil, filters and etc) with the hope it can bring me around 14-15 like it should be, but with no success.

 

Are you using NON-ethanol fuel?

Also winter blends are notorious for bad fuel consumption.
https://www.gasbuddy.com/go/summer-blend-and-winter-blend-gasoline

 

Had the same issue with a 2005 4runner with v8... Hwy mileage dropped from 20 to 17 for the past three years. It stayed constant for so long, thought it was due to engine wear. One day noticed a bit of oil leaking from the passenger side valve cover. Took all the bolts out (they were all loose), and put back with lock-tite. Didn't think anything of it at the time other than it will stop the oil leaking. Next trip, noticed I got 375 miles per tank which hasn't happened in many years. Mileage on that tank was ~21mpg. I've done a lot of the stuff mentioned above as well, so not saying those aren't good advice, but this problem for me appears to be a vacuum leak as best I can tell. FWIW, has over 300k miles as of this weekend.

 

Still no fix for this? I’m having the same issues now. Even with all my mods I was getting 16mpg highway and 14-15 city but suddenly dropped to 9-10mpg. and i’m lucky to get 200 miles a tank. I’ve done all the recommendations new air filter, upper 02 sensor, cleaned TB, cleaned Mass sensor, new plugs, sea foamed in the tank sea foam top end cleaner. And i’ve also tried using a whole tank while keeping the rpm’s under 2500 with absolutely no change. My range says I have 280miles to empty but like i’ve said i haven’t been able to consistently get 200 miles even. I also have snap shots of my OBD readings but nothing looks out of wack to me. My next guess is to drop the tank and check fuel filter and sending unit for a issue. Unless I can find someone who found a fix.

I also just got a mechanics diagnostics tool i’m going to hook up to it and see what i can find.

 

Reviving an old thread. I’ve been in the 10mpg club for many years now with my V8. Was getting good gas mileage, 17-18mpg, then one winter it just suddenly dropped. It got so bad I’ve been avoided driving my V8 4Runner. I did everything, full tune up, new o2 sensors, new maf, removed o2 sensors and had them cleaned and flow tested, checked fuel system pressure, checked exhaust back pressure on both banks. Brakes don’t drag, I can put the truck in neutral and easily push the truck forward and back on level ground.

The only thing I can think of is the notorious cracked manifolds. I am still on the factory manifolds, and I know for a fact they are cracked at the flanges where it meets the heads as they emit a loud exhaust leak tick. The exhaust system is not always under constant positive pressure, it pulsates, and my theory is that fresh air is entering through the cracks via venturi effect and is causing the o2 sensors to read lean and in turn command more fuel to be injected. I would do DT headers, but the job doesn’t look fun for a truck that has seen many salty winters.

I have ODB reader with data logging but I don’t have access to another V8 4th gen in my area to compare fuel trims to.

 

How accurate is the mpg computer? I have 06 SR.V6 4x2

 

I find it shows better than actual. I’m actually getting 11MPG, the computer says 12.5. On my 03 V8

 

I'm using app to keep track of fuel and mpg. My 2nd fill up and it's showing 19.5 mpg. I keep all posted. The app is call fuelio