3.0 problems

[yodaboy4life]

so me and toyzuki have been going back and fourth trying to figure out what is up with my truck. it is a 90 toyota 3.0 stock gears 31s modified air box no cat crapy aftermarket muffler and i seem to be gettin like 12 mpg is this normal or what i am baffled on why this truck is getting suck shity gas milage i need some help cuz im tired of going though soo much gas does any one have any ideas on what i should check or do to figer out and get better milage it would help a bunch i am lookin into getting a new muffler cuz the one i got is getting old.

 

[84Toyota4x4]

You know, my cousin was driving a mid (or early) 90s 4Runner for a while, and he was telling me that he got really horrible gas mileage with it, and it had a rebuilt engine in it that was built by his Dad who is what I would consider to be a supreme engine mechanic, among other things (he helped me build mine too).

His had a modded air box, but everything else stock, with stock sized tires, and he wasnt even getting 15 MPG with it, I wanna say he was getting about 12 or so as well. I was really surprised that mine got better mileage than it, and my girlfriends 4Runner got better mileage than both his 4Runner and my truck.

Not helpful, I know, but just tossing out the fact that it could be fairly common for a heavy ass rig with a motor you have to floor to get to go anywhere?

~T.J.

 

[Mark m.]

15 mpg is about as good as it gets in those rigs with the V6. Crappy engine.

 

[yodaboy4life]

well thats :rb: but is there any thing i could check that would be keeping it from at least gettin 15 or anything i could try putting on or changing im onpen for any thing here thanx

 

[ToyZuki]

Forgot earlier. I had a k&n filter chargrer and borjla catback system

 

[chevyxj]

How many miles are on it? If its getting tired 12 is about as good as your going to get. On mine I rebiult the engine last spring, it has a k&n, no cat and a flowmaster. When I was on 35's with stock gears I was getting about 12. With 5.29 gears and 38's I can get about 15. Give the thing a good tune up plug, wires, cap, rotor if that hasnt be done anytime recently but besides that its just pretty much a 3.0L, not the greatest motor toyota ever had.

 

[mthompson223]

Give it a valve adjustment. If you find any exhaust valves with zero clearance then you burnt an exhaust valve and you're running on 5 cylinders. It might not be a completely dead hole which is why you're not feeling it stumble.

From my own experience working on these engines, the average driver doesn't notice the engine is running rough until 2 valves have been burnt. A single burnt exhaust valve is difficult to set apart from a good running 3.0, despite the dead hole. A burnt exhaust valve is far more difficult to notice than pulling a spark plug wire. It has to do with the lack of compression a cylinder is making.

I'm assuming you've done all the basic tune-up items like spark plugs, plug wires, cap, rotor, fuel injection cleaner, and the air filter.

Remember too that cold weather brings out the shitty mileage in any motor. My 89 pickup 4wd with a 3.0 only got 15mpg in 30*F weather on a one-way 6 mile commute. Barely enough distance to get the heater operating good.

 

[yodaboy4life]

all the plugs the cap and rotor,wires were replaced like a month before i started driving it and i have maby been driving it for 4 months my dad did all the work on it and the timing belt was replaced along with the valve covers i dont know ill tinker around with it to see if there is anything visable wrong with it it also might have mud in teh air box from the last wheelin trip could that be a factor>? kinda a dumb question

 

[Jay1]

Mt brothers 94 4runner gets about 15 miles to a gallon. but that will change when he puts the headers on he bought.

 

[84Toyota4x4]

Have you checked the tire pressure lately? Dragging brakes? Wheel bearings? Stuff like that?

~T.J.

 

[jim_p]

I would adjust the valves...but I wouldn't expect a huge gain.

 

[GaryTJ]

Oh what a feeling... Nuf said!

 

[Mark m.]

Do a compression check to make sure all cyl. are even.

 

[yodaboy4life]

Have you checked the tire pressure lately? Dragging brakes? Wheel bearings? Stuff like that?

~T.J.

nope ill have to check that in the next couple days never though of that

 

[Boxxerace]

15 mpg is about as good as it gets in those rigs with the V6. Crappy engine.

I have seen 17 mpg, but that could be much better.