I just purchased a 94 4runner with 4" lift, 3.0 auto. I started out with 14 mpg and have improved to 16.5 by tune up. changing differential oil front and rear 90w75 synthetic,and new air and fuel filters. I have two problems that I would like answeres to. I'm not sure if the one of the previous owners changed gears in rear differential because I checked mile markers and came up 1/10th of a mile short. How would I check that. Also I'm getting a valve clicking only at high rpms. It doesn't make noise at idle. Could it be a clogged oil jacket and lifters are starved at high rpms and what could I do for that.

 

With a body lift, it sounds like the previous owner installed taller tires. That is why your speedo / odo is off. If you are 1/10 mile short, then your tires are 10% taller than stock. Just add 10% to your trip mileage and THEN figure your miles per gallon. Also,, you are traveling 10% FASTER than your speedo shows, too, e.g: 50 mph speedo -- 55 mph, actual grounsd speed -- 70 mph speedo- 77 mph actual.

The clicking you hear is likely the fuel injectors snapping loudly. Mine are quiet at lower rpm's, but get louder when the engine gets up around 3,000 rpm and above. The 3.0 is notorious for having loud injectors.

Mike in AR

 

I reduced the tire size from 265/75/15 to 235/75/15, just a size up from stock

 

You can check what gears you have manually. Jack up the rear. Put a mark on a tire. Put a mark on the drive shaft. Have one person spin the tire exactly twice, while you watch how many times the drive shaft goes around. Take that number and divide it by 2. That is your gear ratio.
8 1/4 rotations = 4.10 gears
a little over 9 = 4.56
a little over 10 1/2 = 5.29
etc.

 

Is there any place on the certification label by driver door that tells the ratio that is stock? Thanks for the info on finding ratio Bobakazi and injector noise regularguy412.

 

Yes. You can decode the gear specification on the sticker by using this link:

http://www.off-road.com/toyota/tech/other/4_axles.html

Be aware that some have noted that the info on the door jamb sticker was not 'always' correct. That comes from owners who have owned the vehicles since new. I would say that 'most' 3.0 auto tranny 4Runners came with 4.88 gears ( if they had the 31x10.50 tire package stock). My 92 3.0 auto came with 4.56 gears and the P225 tire package. I recently did the 'spin the tire test' and confirmed that 4.56 gears were what is in the diff and it corresponded with the door jamb sticker. If you have an OPEN diff, ( not a locker or limited slip), you have to spin the jacked up tire TWO full rotations WHILE counting the number of rotations of the drive shaft. That will give you the axle ratio.

Mike in AR

 

I'm getting about 16 mpg and am thinking about installing a lower temp thermostat. Mine works really well and heats up quickly but guage shows over halfway mark. I'm also thinking about gearing. Mine is 4.56 so was probably set for factory tires. Once again it's a 3.0 auto with 235/75/15 tires.

 

hate to tell you but being a longtime 3.0/auto 4runner owner myself i would kill to get 16mpg consistently. I usually only got 12 in town and maybe 14 freeway. that is with a 2" lift with stock 31s and stock 4.88s.

 

Same here! I have 4.10's with stock 225/75 tires and I get the same as you with a new O2 and full tune-up! This blows! You would actually get better gas mileage with a 4 or a V8!!

James

 

I have a 92 3.0 A340H auto tranny-- 183,000 miles. Routinely get 14.3 MPG in strict around-town driving and between 20 and 21 MPG on the highway. I've done a LOT to make sure all the little things are working properly including : clean throttle body, lube AFM door, TPS in proper spec, NGK plugs, new plug wires, new distributor cap and rotor, cleaned EGR valve ( this helps MORE than you know), make sure no vacuum leaks ( especially in intake ducting), new Denso O2 Sensor, tires aired up to proper spec for on-road, mileage per fill-up adjusted for larger than stock tires (large tires travel farther per revolution , therefore, better mileage per the odometer reading) and finally, don't carry any unnecessary extra weight.

Mike in AR

 

I guess I'm spoiled as I have two other 4Runners and get so much better milage. The 91, 3.0, 4.10 gears, stock tires, 5 speed standard gets 21 mpg 30/70 city/highway. My 92, 4cylinder, 4.10 gears, 235/75/15 tires, 5 speed standard, tornado, with 255,000 miles gets 23 mpg 30/70 city/highway.

 

Yeah my old 3.0 got 15.5-16.5 most of the time, although it would get 20+ on highway trips at like 70mph.

Just an echo - that's definitely injector tick, especially if it gets louder and high RPMs and under throttle.

 

Keep the TPS and AFM operating correctly and all the tune-up parts replaced regularly. Also, keep those big tires aired up, when on-road and don't carry any extra , unnecessary weight.

Mike in AR

 

Toyota pickups and such dont really get good mileage from the factory. I know my 89 22re pickup got 16 in town from the factory!

 

I changed my thermostat from 193 to 180 degree and got another mile per gallon. I went from 16 to 17 mpg - 80/20 highway/city.

 

Something I'm missing here, but why does changing the thermostat help mpg?

 

Supposedly keeps the intake cooler so you get a denser O2 charge, so you need less throttle position to make the same RPM's.

 

It doesn't. It could make it worse. By putting a cooler thermo in, the coolant in the engine will actually begin circulating through the radiator before the engine reaches the correct temp. This could cause the ECU to continue pumping gas into the cold start injector and make the engine run rich longer. Running rich ruins gas mileage and accelerates engine wear. Maybe not as bad in our FI engines as the old carb engines. But still, a cooler thermo will NOT help your mileage.

To help your gas mileage:
Tire Pressure ? 32-35 lbs
Make sure cap, rotor and wires are in good shape.
Good plugs (Denso's or NGK's seem to get most raves, but I use Bosche)
Replace fuel filter
Replace O2 sensor
Replace air filter (use stock type...filter better than K&N)
Advance timing to 12° BTDC as long as you're not pinging.
Replace 3.0 gas engine with 2.4 or 3.0 diesel.

That's about it.

 

I second this...Hypertech wants a cooler thermostat installed when you do there tuning for that reason, the engine is always trying to get it up to temp.

 

The book calls for a 180 degree thermatsat so it had the wrong one in it when I bought it. I was wrong on the milage because I'm still only getting maybe 16mpg driving like a granny. I'm very dissatisfied with the auto because with the standard transmission I'm getting 300 miles per tank as opposed to 200 with the auto so I'm selling the auto.