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Discussion Starter · #1 ·
I bought my truck (04 Single Cab 5spd 2wd 2rz with 114K) around a month ago, and I'm getting poor fuel mileage. So far I'm at about 18-19 mpg. I've checked the speedometer with my gps and its almost dead on.

What would you guys do to get better fuel mileage? I figured I'd be at about 21 mpg at the least. I have the tires at the correct pressure, but I am in Alaska and its winter with winter fuel, so that could be part of the problem. I was going to start with checking the air filter or replacing it with a K&N intake that I have sitting around, changing the fuel filter, plugs wires, synthetic oil, ect. Anybody have any other ideas for better fuel mileage? I had been planning on an electric fan in the future which should help a bit as well.

Before I start putting things like the electric fan, intake, changing exhaust, or even turboing, I'd like to be up to snuff as far as stock goes. I've searched a couple threads, but most are ones with guys having specific problems. I don't have any check engine lights on or anything like that, so I'm leaning towards just a general tune up. What do you guys think?:shrug:
 

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Certainly the 1st thing to check is the air filter! Then proceed with your planned tune up! but keep in mind that the main contributing factor to bad milage usually is the o2 sensors start to clog up and die! they are directly related to fuel milage and they directly communicate with the ECM and it tells it what the exhaust gas content is and then the computer sends in the correct amount of air to fuel ratio to run properly. I would take the o2 sensors out 1 at a time and soak the tips in gasoline. Not the wired part and try and use a metal brush to clean it up and re-install and see if it helps.........If it does then you need to replace all the o2 sensors because the cleaning will only last a short while. But at least you will know what's causing it. Also remove the pcv valve and clean it up. No need to replace it they clean up easily and can be re-used.

Read this link to gain some insight into how they function!
http://www.boschautoparts.com/OxygenSensors/Pages/OxygenSensorOverview.aspx
 

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Cold starts and dense oxygen give you more hp but less mpg.
Well said, there is higher alcohol content in the fuel due to the winter climate you live in, this helps with cold starting. You will see a noticeable difference in MPGs when Summer blends become available. If you have prolonged warm up times and have a block heater I would suggest using it as a stone cold engine takes longer to warm up, thus consuming more fuel to get it to operating temperature.

If it ain't broke don't replace it:
Is the resistance in your plug wires lower than ie 10k-15k ohms of resistance? If not they are fine.

To check your air filter if its clogged is simple, take it out look through and see if there is visible light coming through ie the sky or light in garage and not shredded or distinctly worn.

You have a ~70amp alternator, your 2RZ will not like that current draw with electric fans fyi.

If you are experiencing stuttering or rough idle or engine dies then I would aim towards fuel filters but you did not mention these symptoms so it must be fine.

I am an automotive student and current mechanic, take my input with a grain of salt and good luck :waytogo:
 

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I just tested my fuel mileage and im at 7500 ft above sea level. I am averaging 19-20 in the city and 23mpg on the highway all with the supercharger 7th injector fuel upgrade kit at 10psi. I blend my own gas though and i use a 93 octane non ethanol blended with a 91 octane E10 mixture. I find the ethanol really helps with the pinging in higher temperatures. But i am weening off the E10 now that i have the 7th injector installed. but i need to do a tiny bit more tuning and test the fuel at a warmer temp.:shrug:
 

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Discussion Starter · #6 ·
The idle is slightly shaky, but seems pretty consistent with other 4cyl Tacoma's I've had over the years, but I believe they're a non balanced motor after all.

For the electric fan, I'll be putting a higher output alternator in to accommodate it along with a stereo.

I understand the reasoning behind if its not broke, don't fix it. On the other hand I like to change things out when I get into a new (to me) vehicle so I know when the last time everything was done. Who knows what plugs, oil, filters ect were run the previous owner. I know a lot of guys like to run some pretty specific stuff, so I'll try to do the same.

I'm planning on a URD o2 simulator, so doing that along with checking the front sensor like preybird said will probably be a good idea.
 

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Don't use a K&N filter. I got one for my truck (5VZ), not for the "improved performance" but just so I didnt have to get a paper filter ever so often.

No issue at first but after a few months noticed engine wasnt producing a lot of power. It would downshift all the time on the highway and just dogged when I hit the gas (never checked fuel millage but I sure it sucked).

I started checking/replacing spark plugs/O2, etc (it was about that time anyways)... but not much diff. Someone mentioned to check my MAF so I pulled that and it was covered in gunk. I sprayed if off with MAF cleaner and the truck literally woke up after that. I had to clean it every oil change to keep it from getting gunked up until I gave up and sold the K&N. Went back to paper filter and the MAF has stayed clean.
 

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Discussion Starter · #8 ·
That's strange, I did a K&N in my 4Runner's 5vz and it was a solid 2 mpg gain over stock. I agree with you, and have always told myself that I'd get an equivalent size AFE dry filter to replace it, but haven't yet. That was my plan for the Tacoma's 2rz as well. The K&N gets nasty dirty up here, so its usually better to replace them rather than try and clean them.... or maybe I just do it wrong.;)
 

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ADMlNAHATER
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Don't use a K&N filter. I got one for my truck (5VZ), not for the "improved performance" but just so I didnt have to get a paper filter ever so often.

No issue at first but after a few months noticed engine wasnt producing a lot of power. It would downshift all the time on the highway and just dogged when I hit the gas (never checked fuel millage but I sure it sucked).

I started checking/replacing spark plugs/O2, etc (it was about that time anyways)... but not much diff. Someone mentioned to check my MAF so I pulled that and it was covered in gunk. I sprayed if off with MAF cleaner and the truck literally woke up after that. I had to clean it every oil change to keep it from getting gunked up until I gave up and sold the K&N. Went back to paper filter and the MAF has stayed clean.
K&N over oil's these filters from the factory or you may have possibly after washing/re-oiling.
Letting it dry or hitting it with an air hose (light pressure) to get the excess off of it, and your good to go.

I myself would like to mock up my stock airbox to bolt in with my turbo setup.

There is nothing wrong with your truck.

Once it gets above 60, 65 degrees your mileage will improve 10-20%. Its like this with any vehicle. Cold starts and dense oxygen give you more hp but less mpg.
Yup, with the trucks mechanical clutch fan, it takes forever for these to warm up in cold climates.
I actually stuffed cardboard between my radiator and a/c condenser and that helped a lot, but I also have a scanguage II to monitor water temps..

I haven't had any issues running a 16" Hayden fan for years, and a 16" high flow SPAL fan when I was turboed, with stock alternator. Idle doesn't bog at all when it kicks on. I use a 20A fuse and no issues. These fans draw 15A at startup at most.
An electric fan would help by quite a bit.

I modded my truck to suck in hot air directly off the exhaust manifold, that grained back some of my fuel economy, in -30 weather, my MAP sensor was reading 70 degree's. :waytogo: donno what that equates to in metric status.. lol

http://www.customtacos.com/forum/showthread.php?t=122894

block off the radiator, once the weather starts getting into the mid 20's, keep an eye on your temp gauge.. Mid 30's and I'd pull the cardboard out alltogether or block it off partially..
 

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Discussion Starter · #12 ·
Today I had some extra time, so I installed my K&N intake. It's almost time to fill up, so we'll see how this next tank does. I think I'll lean towards the electric fan and some better sounding exhaust next...
 

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Discussion Starter · #13 ·
The truck sure is noticeably more peppy with the K&N than without. I didn't expect any power gain, but it surprised me. I still haven't had enough time to drive it through a couple tanks to check mileage yet, so we'll see.
 

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i have 2.4 in mine i added a chip with tune and it clearly runs good but i have high idle and poor fuel milage about 14.75 mpg and have change 02s very many times maf and now chasing leaks in purge system and all solenoids check good and seal off great smoke test comes up no smoke and problem still persist the canister must be the problem does anyone think so or better ideas hopefully thinking .
 

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i have 2.4 in mine i added a chip with tune and it clearly runs good but i have high idle and poor fuel milage about 14.75 mpg and have change 02s very many times maf and now ...
First things first. Are there diagnostic codes being thrown? If so, what are they?
 
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