I'm just over 7 days after rebuilding my 3VZE, and just went through my first tank of gas. All of the driving was short in-town trips for the breakin (just in case something broke, I didn't want to get stranded anywhere.)

It calculated out to about 13 mpg.

Is this normal for a 3VZE? Or, does the breakin period go though more fuel, too?

I'm just wondering if this (13 mpg) is going to be standard for this truck.

DAN

 

im looking into getting a early to mid 90s 4runner or toyota truck and from what people have told me that seems pretty low. not to mention you said your breaking it in so i would imagine your not driving it hard

 

thats way to low if its a stock pickup. myne has 145000 on it and is lifted with 33x12.50x15s and 4.88 gears and i get around 15 town 18-20 highway has the 3.0 when myne was stock i was getting 18-22

 

Well.... First of all you just rebuilt it soooo.... the engine was out of the truck, and the computer disconnected for and extended period of time. And a "new" fresh engine that has better flow is now cleaner is now in the truck. Assuming there is no leaks and its tuned properly you need to give the trucks computer a while to re-learn things. It may run funny or diff MPG's for a while. The drive cycle could take a month to complete. Who Rebulit the engine? vacuum leaks? Intake hose good? Tune-up? airfilter?

 

I did the rebuild myself. The only other hands on any part was the machine shop who did all the machine work on the heads and block, crank, valves, cams, etc.

No vacuum leaks, intak hose fine, and with the rebuild, I replaced everything that might be a problem... I wanted to start with, effectively, a 0-mile motor.

So, if the ECU needs to "get back up on its feet," how long should that take, a month? After that period of time, I don't see much improvement, should I start troubleshooting?

Thanks for the replies... I was worried a little at 13mpg, but haven't done a full rebuild before, so I don't exactly know what all to expect. :-)

 

I've never done better than around 12-13 mpg, 15 highway on my 3zve. They just suck gas. Have you replaced the o2 sensor? fuel filter, plugs and plug wires etc? Brake calipers could be sticking... Any exhaust leaks before the o2 sensor.

Actually I see yours is a 5 speed, you should be doing a little better than 13 mpg. Like I said thats what I'm getting but mines an auto.

 

Wow... I totally forgot to change the O2 sensor (or even test it.) That should have been on the list. I guess that's now on the list for the next set of parts. :-)

Yes, I did swap the rest, fuel filter, plugs, wires, cap and rotor. Front calipers, rotors, and pads been swapped, too.

Do you think it would be best to wait and see if it improves? Or start looking for issues now?

 

If you want to replace the O2 sensor just as part of your "0-mile fresh engine" deal thats prob not an issue at all. Unless you know of the O2 being replaced recently then i might be a good idea to throw a new one in. But Other than that just drive it and give it time like i said it may take a while. If its all "OEM" on the rebuild then i would not expect the computer to take no longer than a month-month/half to pick back up.

 

Sounds good.. I'll update in a month or so, and post what happens.

 

Give it 1000m for the rings to properly seat- you're probably using a little oil too.

 

Yeah, I understand... I just wasn't sure if this would affect the fuel-mileage as well as the oil consumption.

 

Oil consumption in modern engines is at its highest during "break-in" period. After that break in period the oil cosumption should drop almost to where you will never know unless you skip 3-4 oil changes.

 

I found that Amazon.com had the best price on the Denso OEM replacement 02 sensor for my 88 3.0, it was around $80 shipped last month and fit perfectly, I just had to take the 4 screws out of the plastic carpet trim and reach under my drivers side seat to get to the connector, your truck may have a front and rear where my early 3.0 only has a front.

 

I just rebuilt my 3.0 in my 4 runner, lifted it and put bigger tires(33x12.5) 5 speed . I just got the shocks on and just riding around the county side seems to be sucking down the gas . after inspection I will get a better read on it

 

I've never heard of this. Are you saying the ECU has some NVRAM or flash memory in it that stores some kind of learned state of the engine? Can you point me to some documentation that explains this more?

 

its not obd 2. Obd 2 has the abilitly to learn. Not pre obd 2. Your poor mpg may be a sensor that is working out of spec or just your gearing/tire setup or your driving. Were your injectors cleaned/flow tested?

 

My gearing and tire setup are stock. My driving is pretty chill as I'm still in the break-in period.

My injectors were not flow tested or cleaned, but I did replace all the O-rings, etc. I didn't replace any sensors... Which ones would affect gas mileage besides O2? Knock?

 

give it some time . as for the ecu you will want to drive car under its normal conditionss for a while and it should be set

 

this may sound strange to all you guys, first few runs during break in, you should drive it hard

http://www.mototuneusa.com/break_in_secrets.htm


also i think after reset an odb2 ecu , it only takes 50 miles or 25mins+ of driving for it to learn everything


last time i changed some parts like o2 , cat , thats was how long it takes for all the parts

once i put in the new parts and reset the ecu, everything at the smog test station computer was showing not ready, thats includs every singel sensor and everything could throw a code, after driving it for 30 mins 45 miles i went back to the smog check station everything was ready


so i figure it should take only 30 mins driving for the ecu to learn things

 

So, I just took the truck on a 640 mile (round) trip, and the last fill up was right at 19 mpg. It's been getting progressively better. That 19mpg is all highway speeds of 60-70mph WITH A/C on the whole time. YAY!