2002 Tacoma 4x4 Fuel Mileage Problem

Below is the specs on my daily driver. I get a consistent 16.5 miles per gallon and can never seem to get any better gas mileage. I feel like my mileage should be higher. What can I check or what do you think my problem could be. What can I do to see closer to 20 mpg.

2002
Extra Cab SR5 4x4
3.4L v6
5 speed manual
265/75/16 Goodyear duratracs on XD enduro wheels (75% tread life)
138,500 miles on the truck
Old Man Emu lift with Dakar leaf pack and 881's up front
Canopy and line-x bedliner

Just recently installed a deckplate on my airbox, havent gotten through the first tank with that mod yet.

I bought the truck stock and only put one tank through it before the mods started happening and got 19 mpg I believe.

My commute is around 85% highway, 15% town.

 

From what I've been reading about the mileage on 4x4 first gen Tacomas (with the V6), 16.5 isn't very far off from what a stock one averages, which is usually around 18 - 20. Gotta take into account your larger tires, and the weight of the camper shell. Larger than stock tires (especially off-road ones) can have a considerable impact on your MPG.

The best thing anyone can do for the MPG is a cost-free solution; drive it like you've got nowhere to be in a hurry. Speeds in excess of 65mph is where your MPG generally starts to take a dive. If you have a manual trans, try keeping your RPMs as low as possible and coast to a stop (no downshifting). Basically, try driving like a little old lady for a tank or two and see what kind of effect it has. You may very well be surprised.

But I don't think you're going to see the MPG you had while the truck was stock, there are no "mods" that do very much to impact your MPG...the ones that do, hardly do anything at all and aren't worth the cost.

 

I used to get 17 mix city/highway but now with all the weight ive added only getting 14.5 mpg

 

Modifications, mileage seems to be in line with with what it should be before and after mods.

 

Im running 265 75 16 bfg load range E all terrains and get a consistent 19 mpgs on 75% freeway with the auto 5vz. Sometimes cars will start to run crappy when they are in need of some maintainence. Generally the fluids tend to knock off some mpgs. So i would look into doing some general maintainence items on the truck if it hasnt had them recently. Other than that its really who drives it and how they drive it that has the largest effect.

 

thanks for the input. I'll try driving even more like a grandma even though my grandma drives like a racecar driver haha. I had a 2001 TRD with nearly the same specs was getting closer to 18-20 in it a couple years ago.

 

I was at 18.2mpg when I had OME 881s, dakars +aal, 265-75-16 Duratracs, tall shell and loaded with camping gear under sleeping platform.

Now I'm running 883s with cbi plate bumper & ~900-1k lb camper loaded full-time, I'm around 16.7mpg.

How do you drive? I usually run up to/around 3k rpms while accelerating, than shift. Although, it sounds great if I floor it (dumped catback exhaust). That said, I rarely run it higher than 3k rpms. Live at ocean elevation getting the cheapest gas possible.

Possible things to check are wheel bearings/brakes? If there's unnecessary pressure or anything giving you friction, that could sure add to the mpgs? Haven't seen that anywhere, but just thought starters for you.

I'd hope you'd be getting 18ish, as my truck was very similar spec'd: '03 SR5 exCab 3.4L v6 Manual 4x4- same size tires & suspension setup. Also, very similar mileage, now at 145k... 85-90%hwy miles.

All that said though, might just be white paint cuts wind resistance better

 

Those rims are awesome, btw. The truck looks great!

 

I'll have to check the plugs and injectors. This is my 3rd Tacoma, my other two were 2001's! I love these trucks and hope this one stays around.

Thanks for the info. I do occasionally "get on it" but honestly I shift early and have been driving easy. It seems when I drive hard it drops to 15-15.5 and the rest of the time I'm at 16.5! I would have thought when it was stock (at 130k miles...) that it would have gotten better than 19 mpg!

Thanks man, I love it!

 

I'm doing a 100% highway tank this weekend and will report back with my fuel mileage.

 

If you havent messed with plugs that very well could be it. Once them things begin to wear down and have rounded edges your mileage definitely begins to drop. A slightly dragging caliper can implement those mpgs. Easy way to check that is to slip a finger through the rim and toutch the rotor, it will burn if the caliper is dragging at all. The deck plate didnt help mpgs, so dont expect that to have done anything.

I used to get drops in mpgs just like that when my pluvs started to go. I. Ow replace those puppies basically once a year, maybe a lil more....hopefully thats the problem!

Also id highly recommend getting a scan guage or the like! Them things are beyond useful! But set it on mpgs and average mpgs and watch those two read outs like a hawk. I guarantee that will drastically change the way you drive. You end up almost making it a game with yourself to achieve your best mileage when you're driving. Doing that will also suprise you where in the rpm and speed range you get the best mpg! High rpms dont always mean poor mpg. You guys that have watched your readers know what i mean. Being able to monitor those things can really help you find and stay in the sweet spots as long as possible. I wont ever not have an on board OBD scanner anymore. They are highly useful and can quickly pay for themselves!

 

Thanks guys I appreciate all the suggestions. I'll start with the plugs. Are they hard to change out? I'm so used to working on 67-72 Chevy trucks and those old things are cake compared to new vehicles. I hardly know where the plugs are at on my truck, I only noticed 3! Haha. I'll search the website to see if there is a write up about it.

Is tire pressure another factor? What tire pressure do you folks recommend? 35?

Thanks!

 

Tire pressure definitely makes a difference. Higher pressure equals less resistance and better mileage. It'll be a compromise between ride comfort, tire wear and fuel economy to find the right pressure.

I just recently went and tried to improve my mileage: did both O2 sensors, new stock air filter, ran a few fuel injector cleaners. Got back a few mpg but then threw on bigger tires and now getting 13mpg which is still an improvement! That's 100% city driving up a big hill every morning mind you. 100% highway I'm able to get closer to 19mpg.

I'm planning on doing the spark plugs soon too and will report back to see if that improves the situation.

 

13mpg is an improvement?

I'm picking my '04 back up from the dealer this weekend after driving a rental Camry around for the last couple of weeks, getting 33mpg average...kinda scared of what the s/c Tacoma is going to do to my wallet in comparison, lol.

Time to buy less beer I suppose.

 

How are you calculating mileage? If the stock tires were smaller than your 265s and you are not correcting for that if you use the odometer for calculating mileage, you will appear to be getting worse mileage than you are.

Try calculating the mileage using GPS instead and see if you get a different result.

Here's what I do:

Set your trip tick and your GPS mileage counter both to zero.

Drive 10 miles on the odometer.

See how many miles that was on the GPS.

Divide that number by 10 to get your correction factor.

Then once you have driven a whole tank, take the number on the odometer and multiply it by the correction factor before you divide it by the number of gallons you used.

In my case, adding larger tires meant that when I drive 10 miles on the odometer, I actually traveled 11.45 miles.

So if one 15 gallon fill-up looks like only 262 miles on the odometer, it looks like I'm getting 17.5 mpg when I'm actually getting 20. That's a big difference.

 

As MrRiverMan states you need to recalculate your distance with a larger tire. The stock system is designed for 31" tires I believe and a 265/75/16 is 31.6". Not a huge difference there but it's also worth noting street centric a/t tires generally run smaller than spec while offroad centric a/t's generally run larger so the difference could be as large as 2" which would change 16.5 mpg to 17.6 mpg.

Also you shouldn't really expect to get great mileage on such an aggressive tread. They might claim to be an a/t but they are definitely focused on off road performance. Look up specs on your old tires vs your new ones and I think what you find will answer all of your questions.

I just made a very similar switch and my mpg went from 19 to 16. I looked up the specs and found I went from a 41 lb tire to a 61 lb tire and since the diameter was also larger that weight is distributed farther from the axle making it harder to turn.

 

I noticed mine started to slip and it was making me angry a little. Went from about 17-18 constantly to about 15 Of course I added a RTT, front bumper etc. I got a roof rack and my MPG went up to 16 constantly. I replaced my rear O2 sensor due to a wheeling incident and I have yet to check my MPG. But I was at about 80ish miles around 3/4 tank. I'm assuming I have a 18 gallon tank and doing the math it's around 20 MPG with about 60-40 city to highway. My scan gauge is also reading about 19.9 but it's been doing that for a while. But until now I have never really seen 80 ish miles at 3/4 tank. So I'd just replace the O2 sensors and the plugs/wires and see where it goes. Basically a small tune up so it wouldn't hurt to do it anyways

 

So just finished a 200 mile trip and calculated 18.9 miles per gallon using the gauge trip meter (unadjusted for my slight tire size difference..265/75/16 vs 265/75/16).....

I was getting 16.5-16.75 consistently. What changed?

-driving style (drove easier, didn't exceed 70 mph and accelerated slower)

- deck plate mod, though I'd like to think it helped it probably didn't help much.

- mostly highway driving though I did have to use the AC and was in traffic in Portland on i5 so my mileage could have been even better.

I'm happy with the improvement, easily the best tank since I've owned the truck with the lift and tires on it. I still want to change the o2 sensor and plugs and see if I see a difference. And also want to get a scangauge someday too! Thanks for the help folks!

 

Hey OP,

I have the same truck as you. Including 265/75/16 duratracs and shell. Stock suspension. When I first bought the truck (stock) I saw 22-23 mpg on the scan gauge (20-21 actual). Now with the shell and larger tires, I've gone to about 21-20 scanguage (haven't done manual calculations yet)

This is 80% hwy driving pretty quick. And like someone said, I shift at 3kas well. brand new plugs, air filter, diff fluids and engine oil. If you haven't changed these things, it might be a good idea.

 

If your plugs are really old i guarantee you'll gain a lil mileage!

And your deck plate will only aid in a dirtier filter quicker, thats about it...