I have a 1986 4runner lots of miles, doesnt burn oil or smoke.. 31 tires, has header.. Has a strong rich gas smell when u r outside of it, or have back window down...Could stock gearing with 31 tires make such bad mileage, I get about 12? Could the header make it smell rich?

 

Oh I might ad I have a 22re

 

my dads 22re does somewhat decent. but its anywhere from 14-20.

 

mpg i mean

 

You might have a leak in your fuel line or tank, and that might be screwing with your calculations (and wallet).

 

You're probably running rich. How many miles are on the o2 sensor and when was the last time you replaced it? Check the Cold Start injector to make sure it isn't squirting when it shouldn't be. Check the cold start timing switch per FSM or whatever service manual you can get your hands on. Do you have any exhaust leaks before the o2 sensor? Do a tune up and oil change.
The 31x10.5 with 4.10 gearing ratio isn't really helping your mpg, but you should be getting better than 12. I was getting about 14-16 city in 4wd in my '93 single cab 22re 5spd with 31x10.5s this past winter.

 

I'm running rich too. This is making my wallet low.. But after taking off my 33x9.5's it is running faster as well. Belt squeal is getting on my nerves.

 

i got upwards of 20mpg on my '31's and 4.10's and i had a carb'd 22r.

have you done the simple things? like a tune up lol

 

My 89 auto 22re with 4.30's and 31" got 15-17 mpg city driving... But in winter it woud go down to maybe 12-14 depending how cold.

And the gas smell with the rear window down is totally normal, it's the exhaust coming in the window from the vacuum created. They fixed that on newer generations with the air dam at the rear.

 

Tune it up, and is your CEL light on?

If it is, pull the code if it is with a paper clip. No special tools or code readers required.

 

Off the top of my head, not sure if a RE will even run w/o a O2 sensor or not...

But some jack-ass could have put a 22R header on your truck, or it could be an old header where the O2 sensors position interferes with the exhaust flow.


The pulses are not uniform like they are with a stock manifold. They are more like machine gun fire. Your manifold might not be O2 sensor friendly.

And as also said, larger tires DO NOT help with MPG. And, you will NOT get accurate results as your speedo and the odometer its connected to are reading optimistic with the larger tires.