Gas Mileage Crappy

I'm running a 2002 4x4 Taco with a 2.7 four banger and only getting 10.933333 mpg. Plan to do the deck plate mod as soon as it warms up but still thinking 11 mpg is just to bad. What is the mod gonna give me 3 - 5 mpg more????? Just did the plugs, new air filter and the #3 coil pack. Any help would be greatly appreciated, THANKS....

 

maybe check your plug wires and fuel filter? maybe your other coil packs? do you have an exhaust leak? i had a 98 and it had every last one of those problems

 

front end issues or brake issues comes to mind, having gas mileage cut in half like that is more then a minor problem.

also might be injectors leaking, continued dumping fuel after shutoff

 

I thought my 99 3.4 was horrible 13.7 but all i do is city driving.

 

Thanks for all of the possible causes, I'll check into them all. I'm not going to let this thing whip me, because I really like this truck. Gas mileage like what I have is definitely not going to cut it.
THANKS AGAIN

 

Clean your maf sensor. And get a new o2 sensor. I get 20 mpg in town. And 28 on the road in my 96 4x4 with the 2.7

 

Best my 2.7 auto ever got was about 17mpg. 100% steady 50mph highway.
Normal mixed city/hwy I get about 13.

 

Add a pre cat exhaust leak check to that list. My '99 with a cast manifold had a crack causing a decrease in mileage. Wet air filters like a K&N will foul the MAF causing poor mileage.

I get about 15-17 mixed driving with 33s and fiberglass topper.

 

Check spark plug wires, plugs, coils, clean MAF, replace fuel/air 02 sensor, dump a can of B12 chemtool into truck on empty, fill with 1/4 tank, run, redo, then dump Techron concentrate on empty, fill halfway run (do this every oil change), check air filter (replace yearly), check alignment (check at least yearly), clean throttle body, seafoam as a last resort (run half a can slowly through brake booster line).

That's about all I can tell you. I did most of this at some point (except coils) and get 16/17 mpg with 33s and about 400lbs of other random heavy shit bolted to it (bumper, full toolbox, budbuilt skids/bellypan, sliders, sub, etc)

BTW the deck plate mod has not been properly documented concerning MPG increase. I have heard both decreases and increases. It's all hearsay so I never bothered to do it because it doesn't seem worth it and there isn't enough evidence.

 

Winter fuel will also adversely affect your mpg.

 

Not that much

 

There's no reason these trucks can't do well on mileage if everything is working right. My '96 with 250k running 31s, a cap, a set of welded steel racks, and a fair load of stuff in the bed got 19mpg on my last tank (winter gas) doing a mix of city and mountain driving. I'm doing some work this week that I expect to get me comfortably over 20.

Look for exhaust leaks, replace front o2 sensor (use only Denso), clean/replace MAF, plugs (use Denso), check for vacuum leaks, EGR stuck open.

Remember that if your tires are bigger than stock, you need to correct for that when calculating mileage. I created a conversion using GPS to be certain of the mileages.

 

Right now I am in the process of replacing my O2 Sensors on the exhaust. I have gone thru everything else, Cleaned the TB and IAC, replaced the TPS, new plugs and wires, used

$25 BG44K BG 44K Fuel System Cleaner Power Enhancer 11oz.

BG44K, new hoses, belts, radiator, shocks, struts, leafs, front end alignment, new brakes front and back. I will get this thing above a average of 16!

 

Just changed out the 02 sensor with the wiring entering the cab by the passenger seat. Is this 02 sensor considered the front?

 

On my truck the wiring runs along the side of the transmission to the o2 sensor, which is mounted in the exhaust pipe upstream of the catalytic converter. There is a connector very close to the sensor on the wire, and you just unplug and replace the sensor.

 

Although your post was very well thought out and deeply informative, yes it can very much affect mpg. Especially coupled with longer idle times upon start up, longer time for the trans and engine to reach operating temp when driving, a/c compressor running while using defrost, etc..
Winter fuel has less energy than sumer fuel therefore increasing consumption.
It is proven that 10-20%+ decrease in mpg is common in the winter months.

 

One is before the cat and one is after the cat. Both can affect mileage when they start to go bad.

 

Correct, deck-plate mod does not really increase mpg. it will barely help with hp (warmer air and easier to pull in) either. The system will adjust for the different amount of flow without a proper tune for the changes.

winter fuel on it's own will not adversely cause this much loss in mpg. letting the truck idle to warm up, revving unnecessarily, and short drives will affect. The worst my v6 auto got was 11 and that was letting it idle to warm up and short commutes. Seafoam (or other fuel injector cleaners) in the tank every now and then is good maintenance but don't use it every fill up. cleaning the MAF is a must if you have never done it.


Are there any CELs? Rough running? What was the reason for replacing coil #3?

 

The 2.7 combined with auto trans yields the worst mpg of any 1st gen. From all the searching and reading I've done the average seems to be 13-16mpg (mixed). The higher range being bone stock with low mileage, the lower range being older with lift, bigger tires, etc.

10 is pretty low but dont get your hopes up looking for 20, it wont happen.

I also never noticed any difference with or without the deck-plate mod. If I could go back I wouldn't waste my time doing it.

 

Yes I get this, the point was is that it will contribute to the poor fuel mileage. It was noted so the OP may take it into consideration along with every other guess.