Poor Gas Mileage...

I know a lot of questions have been asked about this topic but I'm not finding too many relating to a V6. So here goes...
I have had the truck since mid July, I purchased it in VA and drove it down to MS...I was getting about 22 mpg then (interstate). I noticed a drop in my gas mileage a few months ago so I changed my spark plugs to NKG about 5 - 6,000 miles ago. Since then I have driven to VA and back as well as to TN and I'm still getting around 16 mpg....and that's interstate! I'm not sure what to do. I'm running stock everything on the truck. I'm going to change my oil and rear brakes this week...there is nothing out of the ordinary that I have noticed. The truck has 134,000 miles on it. I checked all the fluids the same time I changed the spark plugs and everything looked good. I'm just not sure why my gas mileage changed so much. Any recomendations to get better gas mileage is GREATLY appreciated

 

Mileage will typically suffer in the winter due to additives in the fuel, letting the truck warm up, etc. Have your driving habits changed, maybe driving faster now than you were when the truck was new to you. Once the RPM's go over 2,000 on the interstate, you start losing MPG's. Also, check your air filter and make sure that's nice and clean.

FWIW, I have a 2007 double cab with the V6 and if I hold 75+ on the highway, I won't do much better than 16 mpg but can hit 18 - 19 if I'm at 60 - 65 mph.

 

I am doing about 75+ usually when I drive on the interstate and I was when I first drove it down from VA (that's the posted speed limit in a few places). The air filter looks good I'm still going to change it with this oil change & I'm converting over to synthetic this time. My truck doesn't usually get over 2,000 RPM when I'm going a steady speed (maybe a hair over). I guess these trucks just don't like winter?

 

I would blame it on the cold season. The air is denser so it takes more fuel for the truck to run in an optimum setting. Plus the additives in the fuel hurt. I typically lose about 3-5 mpg in the winter months.

 

Pogiboy, what lift did you use? I would like to lift mine after I get the mpg a little better

 

Only Toyota can fix the gas mileage problems in the Tacomas either 1st or 2nd gen. The problem is a combination of the engine specs and the gearing in the differential, they need to change the cams so that the torque curve moves down the rpm scale a bit and they need to run no taller than 3:43 gears. This will also require adjustments in computer programming of course. Some of this can of course be done thru the aftermarket but Toyota needs to take responsibility for what is a serious problem in an otherwise great little truck.

 

I have yet to see worse than 18 from mine. This past Sunday I drove about 140 miles one way to meet a bunch of friends for lunch. It was all interstate and I don't think I dropped below 75 the entire trip both ways. Most of the time I was 85-90MPH and I got 18.2 MPG. My truck is all stock right down to Rugged trails with about 15k on the air filter and plugs. It's a 4.0/auto 4x4 double cab. But the truck has about 120k on it. In my normal driving not going over 75 back and forth to work I've been getting about 19.5. I'm kind of missing the 21-23 I used to get with my 4 cylinder but I sure like the double cab and extra power.

 

I have a 2009 v6, new plugs k&n air filter cold air intake (ca legal one) and combined I'm getting about 14 mpg... and I drive easy! Half highway half street, it does have 184k miles but no engine codes or anything wrong with it. IDk why I'm getting such bad mpg?

 

huge difference with gas type and season.

in the winter = 16-17mpg
in the summer = 20-21 mpg
in the fall/spring = 18-19 mpg

 

In California it's summer.. I average like 15 wtf I don't get what's wrong

 

check tire pressure

 

That wouldn't account for a loss of 4 mpg tho.. even if it was off by a decent amount

 

It can vary due to speed limits (EPA estimates are for 55 MPH, not 65 like in CA), heat soak (this 100+ weather can pull timing from an engine), and the biggie...driving habits. If I baby it and only go 70 MPH on the freeway, I'll probably get 20 MPG...but thats no fun!

 

I have little lift, but e load 285 ko2.... I get about 10 city and 14 highway. I don't drive aggressive by any means, but I don't like holding up traffic behind me, making them pass in another lane.
Little over 200 miles per 19 gal tank isn't very satisfying :/

 

Question to those who are knowledgeable!

Is higher rpm less/engine load (2-3.5k) or lower rpm but more engine load (1.5-2k) "better" for gas mileage?

I.e.: does the engine accelerating at 1.7k rpm under more of a load cause the ECU to spray more fuel than it might at a lesser load, but higher rpm?

 

I would think lower rpm would still be better, the torque is there. And at high rpm it might be a little less gas per combustion but you have like 3x more so that's my thinking

 

wats the expected lifespan of our catalytic converters? in my old truck they clogged or somethin and my mileage payed dearly for 6 months, then the truck went to no run mode lol. i ask because im starting to see the same decline in my mpgs, im usually 14-15, and my last trip was 12mpg, and ive changed plugs, filter, cleaned intake and maf. so now researching converters

 

I don't know the lifespan, but that's a pretty good idea about what might be going bad! I just gave it a "tune up" where they run cleaning fluids to clean carbon out, nice power increase but no mpg gains

 

I get about 18 mpgs that's a 50/50 mix of highway and city. I'm running a 3" lift and 285 10 ply bfgs so they're heavy. Stock gears and all, so 15-16 is really low for stock

 

OP, what is your tire pressure currently? You can always do the chalk like test, as well.

You'd be very surprised how much drag/rolling resistance the tires will makes with a drop in just 5 psi. Especially as the tires get wider. So imagine if they are even lower than their recommended psi.

Also, at 135k miles, your fuel filter will be thoroughly clogged. Which will affect your mileage. I promise.