Struggling with 12 mpg

@Chandler

 

But if he's not throwing codes after removing his catalytic converters then something is up...maybe his CEL bulb is burnt out

 

https://www.thelokengroup.com/site/wp-content/uploads/2016/06/more-info-button.jpg

 

I think only the front ones are monitored, the ones that are built into the manifolds

 

Ah that makes sense. I have a 1st gen so it's different for me I suppose, front or rear will toss a code if bad but we only have 1 or 2 cats depending on the model.

 

There is no 02 sensor after the secondary cats on the first or second gen trucks so they will not throw a code if they're removed

 

The thing about these mpg threads is we really dont know about people's driving habits. one persons "moderate" throttle would make other people's jaws drop.

A few things that I believe to be true...

- if you're fond of driving down the freeway over 70mph forget about good mpg
-you cant do jackrabbit starts off every stoplight either
-check tire pressure often
-try a different brand or octane of fuel for a few tanks and see if anything changes

Also, a little scan tool is great for watching fuel trims. If the long term trims are high you could look at a sensor issue or fuel calculation issue (pcm is struggling to get fuel calc under control). if fuel trims are low/stable then the pcm is doing everything correctly and it's a safe bet to chalk it up to poor driving habits

Best advice I've gotten is to drive like there is an egg under the gas pedal!

Other than that, buy a Prius

 

You mean I cant do 80 down the interstate

All joking aside, can you elaborate on the fuel trims? I have a ScanGauge and would like to look into those if it reads them out. What are 'normal' numbers?

 

A good rule of thumb is anything below 10% is ok. Remember short term can jump around depending on load, going up hills, etc. Its the long term that really tells the tale

 

My mileage got better with winter fuel. I think it is a California thing? Speed under 70 mph Max is also a way to increase mileage. Highway driving (constant speed) vs. city driving (stop & go) will give you higher mileage. 15 mpg city and 19 mpg highway are my common corrected mileage range, driving carefully. I have a 4WD V6 auto. DC, the worst mileage model.

 

It has a v6 4L

had it for 4 months

i fill up, reset trip meter, drive until close to empty, refill tank, divide mileage driven by gallons refiled.

live in GA, small hills, ranging from 30-90 degrees, same on highway vs city driving

tire size 265/75 R16

stock gearing

automatic

mix



i get about 220 miles out of 18 gallons

 

Is it supercharged?

 

i wish

 

Dang im pretty surprised how low and how common it is to be that low for a v6 2nd gen taco. Getting 12-14mpg city is close to what we get on the v8 Tundra. Something must be up lol

 

Yea but these trucks have never gotten good fuel economy

Maybe we just didn't notice because gas used to be cheaper lol

 

What is the engine’ operating temperature after warm up? Should be somewhere between 200-215 deg F. Any temp lower than this will have a drastic negative affect on fuel mileage. A new quality thermostat should be installed.

 

Add 4% to the odometer.

 

Do you have heavy aftermarket bumpers? How much extra weight are you carrying around like tools and crap. That will hurt your mpg? I have about 75 lbs of tools around every day and drive 100 miles a day for work up and down the nj turnpike and I still average around 17-19 depending on how fast I drive and heavy winds . I hope you find your soarce of your poor mileage

 

Most do not realize that fuel delivery is severely affected by engine temperature, I would change the thermostat and install a name brand 195 stat or an OEM stat. Also, can you verify that the PCM is going into closed loop? A simple scan tool should let you see this happening. Does the engine have any vacuum leaks? Has anyone tampered with the emission control system?Has anyone checked fuel pressure? Have the fuel injectors been replaced? MAF sensor reading properly? Approximately 6 grams per sec at idle and should rise smoothly with RPM . Hope this helps

 

I get better millage than that out of my 2012 4.0L with E range tires (same size) and some extra stuff like a steel bumper and winch. I would say 17mpg average on a tank is about what I can expect.

If you dont have a OBDII scan tool, I would recommend getting one. But in the meantime your dash temp gauge should read right dead center (~190 F) after 10-15 minutes. If you do get a scan tool, it would also be good to confirm that there arent any active codes or pending codes. Even if the check engine light isnt on