Hello,

after purchasing my 91 3vz 5 speed 4runner a month ago, I noticed I had been getting horrible mileage (around 9.5 mpg) I know that stock 4.10 gears and 31 inch tires don't make for the most efficient combo, but as I knew the vehicle was older I went through the following maintenance steps to see if it got better:

basic LOF
air filter
fuel filter
spark plugs and wires
distributor cap and rotor
02 sensor

Today i picked up a timing light and manually set timing, so I have not yet been able to confirm if that was the problem, however i only had to move the distributor ever so slightly to set it at 10 degrees advance. I removed the catalytic converter tonight to see if that had anything to do with it, but alas, it is too loud to drive around tonight. Going to order a new cat asap. I also know that the EGR system is not working properly, and that it seems to be frozen shut (sluggish at low rpm when cold but runs fine when warm) My question is, in addition to the above items being changed, what else should I try/look into to get back to "normal" mpg numbers with the 3vz?

Thanks

 

Without knowing you driving habits it is hard to say.

Go as easy on the skinny pedal as you can

How much stuff do you cart around that you really don`t need the more weight the more fuel used.

tire pressure should be the proper pressure for your use.

Does the 91 have the ADD or do you have the manual Hubs I know switching to manual Hubs gave me a difference.

 

I generally do take it fairly easy on the skinny pedal. Tire pressure on the Goodyear Duratracs (31x10.5x15) is right at 15psi (as recommended on sidewall, seems to roll decent and not too firm) The 91 does have the ADD. I plan on doing a manual hub in the relatively near future and hope to improve the mileage there. Is 10mpg not completely unheard of for one of these rigs stock with the 5 speed? If that is in fact normal then I am okay with that, but from what I have read some people seem to be getting 16-18mpg easily out of the 3vz.

 

15psi tire pressure seems low. Usually 30-35 psi is the norm for most.

And 16-18 seems like that's on the higher end of the 3.0 mileage. 12-14 seems the norm. I had a lifted and such 94 and I got 8mpg.

 

Are you calculating about 10% more for the larger tires?

 

Not having those tires I can`t say But I run 35 psi in my 92 4Runner

 

okay, so yesterday I went ahead and swapped out the PCV Valve and purchased a vacuum gauge. Vacuum seems to be pulling fine from the intake. I went ahead and aired up to 37 psi, which greatly improved rolling on the street. Went ahead and gassed it up and drove to and from work . since my speedo/odo/trip arent working I used my GPS to calculate mileage and was still at 9mpg. However I did notice a few things yesterday.

1- The EGR seems to be stuck in the "closed" position (poor response/power at low rpm but runs normal once at normal operating temperature)

2- Seems to run around town just fine, but once on the freeway it is very difficult to pull up any relatively steep inclines. Could this be a sign of a fuel leak/ going fuel pump? I have already changed the filter so I know that is good, but maybe the regulator or injectors?

3- The speedo/odo/trip meter. Is my speedo cable the only speed indicator that gets sent to the computer? Is having the speedo cable down going to greatly affect the way the motor runs? (from what Ive heard, automatic- speedo cable is a big deal, manual- speedo cable is not)

when I bought the vehicle the previous owers had just advanced the timing like crazy to get power out of it (17 or so degrees) but I would much rather try and find some happy medium of having at least "driveable" power while getting the mpg as high as possible