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Discussion Starter #1
91 V6 Manual Trans 31 10.50 15 tires


New Engine
New Spark Plugs
New Fuel Filter
Pulled and had injectors professionally cleaned
The cold start valve is working properly
New Plug Wires
New O2 sensors/Cat converter/muffler

Significant improvement in power, but still 11 mpg.

What's next?

Any help appreciated!
 

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When you say new engine, do you mean remanufactured? If so, have the rings seated yet? If a truly new engine, do you know where it was made? The "new" castings are usually from China and are fairly crappy quality.

Are the brakes dragging on any wheel?

After a few thousand miles, the plugs should tell you if it's running right.

I'm assuming valves were adjusted on that new engine.

Try adjusting timing to 12 deg btdc with jumper set. Use ALL stock Denso for plugs, wires and O2 sensor. (NTK/NGK O2 sensor may be okay.)

Make sure no vacuum leaks or cracks in the air hose between air meter and throttle body.
 

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Discussion Starter #3
Thanks for the info. The motor is a rebuilt (short block)...I should not have said new.

I had wonderd about drag on the brakes, or if something was causing friction to slow the vehicle.... but never checked. I will do that.

I went by Toyota and got a diagram as to where all the vaccum hoses connect. I need to double check and make sure I don't have leaks. I did have a few but are repaired.

I took the pickup and had the timing adjusted and the mechanic said it was "OK". I used NGK plugs and OEM Toyota O2 sensor.

If it is running too rich...what will the plug specfically look like when I remove it?

Again..thanks for the info.
 

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I am having the same problem with milage. I am about to replace to the o2 sensor and the fuel filter.
My egr isnt hooked up, just bought the truck and it wasnt hooked up as in no vacume line to it, does this matter? Ive heard the EGR can be faulty on these trucks.
sorry my truck in the a 91 3L, standard. 160,000 on truck, under 10,000 on rebuilt engine. just did the spark plug and air filter. Thanks
 

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A working EGR valve will reduce combustion temperatures. It has been suggested that's a good thing because of the head gasket issues these engines are known for.
 

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mpg

I was getting 18.75 hwy, 93 dlx ext v6 w/ 32/11.50/15s, had new timing belt installed with all new pullies and water pump sence it was open, myg is now 13 at best ! Was worse too, but I found the vacuum line broken off at what I believe is called theegr vacuum modulator. the piece is pricy so i siliconed it and mpg and power went up, but my mpg still isnt as good as it should be for some reason. Point beibg check those lines in that area maybe youll find something..hope that helps. :)
 

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TOYsRus
11Tundra Limited TRD
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13 to 15 is all I get on my 91 V6 since I put the larger tires and new wheels...
kinda figure it is what it is.
 

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question :killer01ws6 : I have BFG KO 32/11.50/.15s on my truck and on a 600 mile round trip I got 18.75 no joke. in town 16, and I will get it back as soon as I figure what the problem is, what size are your tires ? I have 4:46 gears, not 4:11s too.
 

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3.0 head problems

My truck has never overheated since I had it and the guy that I got it from said the same and at 150,000 it was taken in on factory recall and the heads were redone. Now I dont know if the heads are different or just the gaskets but its gone andother 90,ooo or better without any problem. Its a fun truck that for sure ! Thinking of putting a straight axle under it, I have one on a parts 85, anyone think its worth it, Ive never been stuck or broken so far with factory frontend but hear storys on line all the time. straight axles look far better but ride like crap
 

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TOYsRus
11Tundra Limited TRD
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question :killer01ws6 : I have BFG KO 32/11.50/.15s on my truck and on a 600 mile round trip I got 18.75 no joke. in town 16, and I will get it back as soon as I figure what the problem is, what size are your tires ? I have 4:46 gears, not 4:11s too.
I put 275-70RT-16 Hankook tires on American Racing Atlas Polished Wheels
love the look and tires have great traction... mileage... yea.... ha

I don't know my gear-set ratio yet.
 

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YOTA Master
'93 2wd P/U
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Those 3VZE 4x4 trucks don't generally get good mileage, but in Texas (I'm assuming on generally open raods) I'd sure expect it to be better than 11mpg.

Is there somewhere you can take it to have the emmisions checked? this would tell a lot about the mixture. You say you replaced the O2 sensor, but did youcheck to see if it is working/getting it's signal to the ecm?

Go to the underhood diagnostic connector and measure voltage at the Oxy terminal. While the engine is hot and running at 2000rpm it should fluctuate quickly back and forth between 0.2V and 0.8V If it is sluggish or stays below 0.4V then it will drive the mixture rich.

Also check to see if the harness to the O2 sensor is damaged where it goes over the exhasut pipe. It is not uncommon to find the harness hsa been melted from hanging on the exhaust. The sensor "wire" is actually a sheilded wire and if it gets hot enough the sensor wire will short through the inslulation to the shielding and pull the signal low driving the mixture rich.

Also check the voltage from the coolant temp sensor. High resistance in this circuit will cause it to runn richer than normal. You should find between 0.5V and 0.8V with the engine fully warmed up.

Other than that double check the cold start injector that it does not drip, check the timing (ignition and cam timing)

Hope this helps
 

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Mpg

Those Hankook tires work out to be about 31 1/2 in hight and 10.83 wide, I run 32x11.50 and get at least 18 mpg hwy with 250,ooo miles on the motor, mpg has dropped with new water pump, timing belt and pullies but you should get far better than 11 mpg...something else is wrong for sure ! Cjould the timing belt is not correct, or egr, I think egr personally. when I lost vacuum I got about 10, fix vacuum leak and getting 17 right now hwy, will know next long trip if its getting any better. Oh yea and thats with arizona gas which is a blend of gas and ethey-alcohol and cuts mpg by at least 10 to 15 percent. New Mexico has real gas and it makes a huge difference !
 

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TOYsRus
11Tundra Limited TRD
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we have blend gas here in Ga and Al also.
I get better than 11, but 13 to 15 is my adv which is always some town and some highway. I have not had a full highway tank run since I put them on. I need to go on a trip ha.
 

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TOYsRus
11Tundra Limited TRD
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144 Posts
Hmm, sounds like i need to change plugs and wires.. maybe have my valves lash checked and timing.
 

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Does anyone know how to check if the egr is even working?
When i got the truck they had plugged the vacum line to the egr, im thinking its not working then, but when i attach it and drive for a bit i dont notice anything diff, except when im at an idle it idles down to about 500 rpm. I asked a mech and he said they can be what you wanna call broke to a degree and they open to soon and cause this poor idle. What kind of oil are people running? Im running just 10w30 castrol gtx. im wondering if it would make a diff if i put in 5w30?
Also has anyone done a compression test on there trucks and if so what are they getting?

Thanks
 

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TOYsRus
11Tundra Limited TRD
Joined
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144 Posts
Does anyone know how to check if the egr is even working?
When i got the truck they had plugged the vacum line to the egr, im thinking its not working then, but when i attach it and drive for a bit i dont notice anything diff, except when im at an idle it idles down to about 500 rpm. I asked a mech and he said they can be what you wanna call broke to a degree and they open to soon and cause this poor idle. What kind of oil are people running? Im running just 10w30 castrol gtx. im wondering if it would make a diff if i put in 5w30?
Also has anyone done a compression test on there trucks and if so what are they getting?

Thanks
Hey D,
You will get better answers starting your own thread vs asking in someone elses on a different subject. Also many of the things you asked you can find in the Feq asked questions or a search.
Happy reading.:welcome:
 
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