MPG Questions

I've got a really cool little 2002 standard cab Prerunner (2.7) I-4 that I love to death, but it really doesn't get the gas mileage I would expect. 17+ all around. Just over 20 on the freeway at 60-65 mph.

I replaced the spark plugs earlier this morning and the old plugs had a wide gap and indicate the mixture is too rich. The air filter is clean. I have no other ideas to offer than that.

What's next? What if the new spark plugs aren't a miracle fix? Where do I go from here? Thanks guys.

 

Basic overall tuneup.air filter,fuel filter, pcv.make sure brakes aren't sticking.I get 22ish in my 97 2.7 with 33" tires and stock gears.

 

Thats about what I get too.
If I'm hard on it 100% city I only get 14-15mpg
Generally though I'm about 17-19mpg mixed.

 

My 3.4 gets 17 in town. 22 highway. Your pickup gets about standard for a pickup. Not very aerodynamic!

 

I should be getting worse mpg than you (with an extra-cab, 4x4 and automatic), but I get 19-24 mpg, driving like a little old man. Since yours appears to be running rich, that could indicate the problem. If the plugs are dark, it might also mean worn rings. I'd would start with a compression check, and hope that its something else like a bad sensor.

 

I have 2 reg cabs, 2.7's and they both get about what you are seeing. Been that way for several years on both rigs...

 

My ext cab 2.4 gets 300 miles per tank so thats 20 in town. Freeway I usually see a few more miles per gallon

 

NO, NO, NO!!!!

Don't even mention worn rings. That would be, like, you know, expensive.

I can replace the fuel filter and/or C02 sensor. I can live with 18mpg, But I really don't want to get involved with major money like worn piston rings.

FWIW: My truck has 218+K miles but the first 206K were all freeway commuter miles. At this point in the trucks life it could be just about anything, but maybe that's just the mpg that high lift trucks with big fat tires (265-70-16) get. It's just that somehow I expected better.

I'll update this thread as I make changes and document the mpg differences. Thanks for the advice.

 

Yep. You could be on a hunt for something when there's nothing. I finally gave up on mine as I was convinced I have a problem. Which I may in fact do. But I'm not gonna go crazy over it anymore. Just gonna live with it until I can throw money at it. I plan to do a major top end rebuild in the future. Saving my pennies. Gonna tear it down and replace any and all sensors and gaskets I can get my hands on. Figured I'd just wait and do it all at once. Unfortunately if I do have an major increase in mpg afterwards, there's no telling what the cause was as I'll be replacing so many things. I thought about leaving the sensors for last and doing one at a time. But Idk. Figured it'd be a good thing to do that way I know what all has been done and when. And keep all the leftovers as spares. Needto learn about how to check valve clearances and all that shiz, but yeah. Not worth it to go nuts. Your mpg isn't horrible. And yes the tires and lift and (in my case) major wind resistance with all my light bars plays a part. I also am wondering if the Speedo being off affects the numbers you get when determining your mpg. From what I understand the difference in speed (in my case about 5mph faster than it says) adds incorrect mileage and changes your numbers. Idk. It's all confusing to me. I use an app that records my mileage as well. So I don't even know what I'm getting is accurate. Which is about 14 mpg. Seems really low to me for a v6. I've never seen anything above 16. But it may just all be from the 33x12.5's with 29psi in front and 26 in rear. As well as the wind resistance. Or maybe my wheel bearings too. Probably a combination of everything. So yeah I'm gonna wait until shes in tip top shape and then start to tackle into the mpg issue deeper. Right now it's just one of those "you don't drive a prius" mindsets and I live with it. From what I gather that's the consensus around here. Not saying you should ignore trying to increase your mpg, just to be aware that it could be anything, or nothing and just the facts of life with an older vehicle.

 

my 2.4 got about the same, then I put in a less restrictive permanent air filter, I also removed and cut off the 90 inside the fender, then hooked it back to the air box to keep only "clean" air going into it so it could breathe better and it went up to 19/21mpg. removing and cutting off the 90 on the fender duct serves the same as doing the deck plate mod but without the hack job look, it stays looking stock.

next I replaced the injectors with the upgraded 4 hole injectors (mainly trying to solve the rough idle, which it didn't) but after the injector swap it went up to 21/25mpg. not sure if that was all because of better atomization from the 4 hole injectors or if my old injectors may have had "slight" issues but there it is. well worth the $120 investment in them.

that's what had success increasing mpg for me

 

You could throw a lot of money at it and not see much increase. You're getting about what most others are getting, it's the nature of owning a pickup.

 

I get 22-24mpg daily driving my '97 2.7 extra cab 4x4 with 31"s and 300k on the clock. the economy of this truck has been the only good thing about it