85gijunk4x4

I know 3vz's suck in general, but ever since I started driving mine it absolutely sucks, and aggravates me to no end. I hear all the time 3vz's don't get that great of mileage, but mines been running about 8mpgs, I can probably burn a whole tank in about 40 miles if I really stay on it.

I've tuned the truck up with all new plugs, wires, cap, rotor, and air filter. I know I used whatever I got from AutoZone, but I aimed for the good stuff, still not dealer quality. That didn't do a darned thing. Still about 8mpg's. The truck runs totally fine, its quick, peppy, no misses, shifts fine, no hesitation or jerking etc. I must say though, it idles just alittle rough...not so much rough, but it sounds like I have a mild cam. Exhaust smells just a tad rich, but not much.

The plugs are gapped to spec, all the wires are on, nothing backwards, no vacuum leaks, timing is right on (was at 12deg but I went back to 10 hoping it'd bring my mileage up)

So what do you veezee guys do to keep your mileage up? This is my nice truck so it never sees dirt, and I usually keep it below 3k. Lately I've been a grandpa and not even breaking 40mph, mostly open country roads, and still not managing to get more then 130 miles on a full tank. Should I check sensors? electronics? Tweak something here and there?

Oh, and forgot to mention, my buddy just bought a 90 4runner, 3vz, auto, only 180k (mine has 130k) and he's getting about the same mileage under the same circumstances (fresh tune up, timing etc.) and on both our rigs, we randomly smell raw fuel in the cabin every now and then, maybe once every day or two.

Before you ask, I know my 02 is probably no good Would that bring me up to 20mpg if I replace that? HAHA

My rig: 1988 3vz a340h 4x4 (hubs always unlocked) 129k 31x10.50

Inferno451

I don't know about 20mpg, but an o2 sensor sure isn't going to make it any worse!

ksti

With 8 MPG you would almost think there's a leak somewhere. I'm sure you checked.
My 3vze was getting around 14 MPG in town. My timing is also set at 15o BTDC so I'm sure this also affected it.
I put in a Denso o2 sensor about 2 weeks ago (had never been changed).
Its not my daily driver, but I drove it everyday until I got real low on fuel and just filled up last Sunday and now I'm getting approximately 16 MPG.

An improvement that I can live with and I think if I back down on the timing it might squeak out maybe 1 more MPG, but I'm going to leave it as it is, just runs better this way.
Put one in and see what happens. Good Luck

Gamefreakgc

You're getting like 7-8 MPG. Go buy a Hummer, it'll get better gas mileage!

O2 sensor will help if you think it's bad. They only last ~90k miles. There's many things it could be, any CEL codes? You might need to service your fuel injectors, they could be leaking or spraying instead of shooting a stream causing bad compression. Mine gets 17-18, 90% stock.

85gijunk4x4

I've been thinking theres maybe a leak, sometimes when I start it cold it'll fire then shut right off before it even begins running, almost like the fuel system isn't holding pressure. As far as the fuel lines and such, I havnt seen any leaks.

irnenginer

When my mileage went to crap and I smelled gas in the cab it was a leak of the pulsation dampener. It started out hit and miss but before I replaced it was pretty strong and constant. Is it stronger on the passenger side? The leak also made it hard to start after it sat overnight.

It is located on the back of the passenger side fuel rail.

You can jumper +B and FP on the DLC and look for leaks.

Redeth005

I had a huge gas consumption problem with my 3VZE. and i ended up having tons of problems. Just letting you know this motor will probably never get you 20MPG. I had my engine completely rebuilt and i remplaced all my hoses and sensors with brand new ones right off the dealership parts department. And even with everything ive done i have never gotten better then 16MPG all HWY. My truck doesnt get 40mpg to a tank like yours but it surely doesnt get 20 per gallon either. I range from 13.70ish to 16.03mpg with a mix of HWY and Street. I never drive the truck with a lead foot, i always keep it at 60-70mph, hardly ever need to use 5th because of the speed i go and i usually always keep it at 3k-3.5k RPMS.

Just FYI before you get your hopes up high like i did gaining tons of wishful thinking and hoping for 18-21mpg haha. that was a total downer for me.

Gamefreakgc

Wait... wouldn't driving in 5th improve fuel economy? Lower RPM's = less pulses by injectors = better MPG?

Aftermarket muffler jobs increase MPGs , mine went up by about 20%

motocrossaddict223

With my timing at 15 degrees i got a solid 18....but i drive like an old person, shifting at 2k-2.5k and using 5th as slow as i can. My motor isnt even fully rebuilt, only the top end. It has cams, efan, exhaust and an air intake. Other than that im completely stock. With factory timing i got 19-20.

Redeth005

I meant that I rarely use it because I dont drive fast. But thanks for the tip. I'm gonna try that out and see if theres a difference.

I envy your mileage bro. What size tire are you using? I'm also gonna try this method of yours. I usually shift at about 3k rpm.

motocrossaddict223

What have you forgotten about my truck already, i wasnt gone for that long!? I'm running 31x10.5

bone collector

Any stored codes?? I get about 18ish mpg... so 8 is absolutely horrible. O2 will probably help a lot. Does the oil smell like gasoline?? Im almost wondering if the cold start injector is stuck on... Any problems with heat temps?? As in the engine still thinks its cold and is still running the cold start?? Just trying to think outside the box a bit to give you ideas. I will definitely do the o2 sensor and check for codes and start from there

p.s. the automatics absolutely suck for getting mpg......

motocrossaddict223

Oh yea i forgot to mention that, when i had my auto i was getting about 15. So i saw a 3-5 mpg increase swapping to a manual.

85gijunk4x4

i'm not asking for 20, but if I can get atleast 15 i'd be happy. No codes saved, never thought to smell the oil lol

Exhaust smells like slight gasoline, yes.

I have an aftermarket muffler, its a little dinky glasspack type straighthrough thingy, but its not all that loud, its pretty quiet but sounds good.

I'd give you specs but I don't have any...I trashpicked it

motocrossaddict223

Do you have a cat? I forgot that i only have half of my cat, so that probably affects my mileage. A clogged cat would definitely affect mpg.

bone collector

your first post said you had an auto but your signature says its a 5 speed. So pardon my confusion. Here is what I would do so take it with a grain of salt. I would change the o2 sensor since you said its bad anyway. Get a denso!! Ive heard nothing but complaints about the bosch ones on the 3vze. Then reset the computer and drive it. Still not happy?? set the timing to 15 degrees and open the afm up and adjust the fuel wheel 2 clicks lean. should drive like a champ and get 15-18 mpg.

https://www.yotatech.com/forums/f116...stment-203287/

85gijunk4x4

yup, have a cat. A big one too. I've seen smaller cats on a school bus for petes sake!

how would I come about checking the cloggedness of it?

85gijunk4x4

2 different trucks hehe.

Might I add, my 5 speed 3vz was getting about 15mpg 90% off road

motocrossaddict223

I'm not really sure how to check, i guess you could take it off, if you can without breaking the bolts. I had to torch my bolts off.

85gijunk4x4

HAHA! good one I had to torch of all the other toys I own too!

I know you can find aftermarket one for about 40, the kind you have to weld a flange onto. Maybe i'll just swap to one of them, they're a heckuvalot smaller