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Discussion Starter #1 (Edited)
I'm going to post this here even though I'm writing about my Tundra since its a 3.4l motor issue. Specifically I've got a 4x4, 02 Tundra with 4000 original miles, 3.4l engine and a TRD supercharger. In short my gas mileage stinks. I drove to a dealer out of town about 2000 miles ago to have the unit put on. On the way up, the truck got 20 miles to the gallon. On the way back with the supercharger it got 22 miles to the gallon. I drove it around town for several hundred miles and didn't pay attention to the fuel economy. I then took a 500 mile road trip. I was shocked to only get 15 miles to the gallon on the way down and about the same on the way back. This was using the cruise control and travelling at the posted speed limit. I then added a lift and 285's. The mileage has since dropped to 13 miles per gallon. Last weekend I was driving into a 45-50 mile an hour head wind for 60 miles. I went and fueled up tonight and just about passed out. The truck was at 9 miles to the gallon. I recently ordered one of Gadget's URD kits to hopefully help the situaiton. I'm looking forward to installing it if Brian can figure out where he sent it. The question is, does anyone have an idea why my gas mileage took such a sharp drop after installing the supercharger? I can understand a drop with the bigger tires, but at the rate I'm going, I'm going to need a fuel tanker to follow me when I take long trips. I also have a non supercharged 96 Toyota Taco 3.4l with a 4" lift and 32's and I've never got below 16 miles to the gallon in that truck. If this Tundra can't be healed, the supercharger is getting pulled, the mileage re-evaluated, and the truck sold if the mileage doesn't improve. Any ideas or similar stories?

p.s, I've been an observer here for a long time and am a member of TundraSolutions, just not many Taco guys over there. I also just noticed this should be under engine/performance. If a moderator could move it, that would be great.
 

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I have 59,500 miles on my 02 tacoma and it's been supercharged since day 1. I get 20-22mpg on average during the spring-fall time and 18-20mpg during the winter months (I'm in NH).

I get 320 - 350 miles per tank during the sprint - fall time and 300 miles tank during the winter.

(02 5 spd sidestep)
 

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tacoboost02 said:
I have 59,500 miles on my 02 tacoma and it's been supercharged since day 1. I get 20-22mpg on average during the spring-fall time and 18-20mpg during the winter months (I'm in NH).

I get 320 - 350 miles per tank during the sprint - fall time and 300 miles tank during the winter.
Thats' probably with a 5 sp right? Regular cab, Extra cab, or double??? 4x4?? That also makes a difference. Especially with ADD.


I get about 14-19 depending on driving style(automatic). Best I ever got was 22 on a 150 mile trip when I was following a caravan of vehicles that were towing trailers at about 45-55 mph. I didn't have the wind drag and was going at moderate speed. For the most part an automatic will get less gas mileage than a stick in the order of 2-4 mpg less.


Triple BB said:
The question is, does anyone have an idea why my gas mileage took such a sharp drop after installing the supercharger? I can understand a drop with the bigger tires, but at the rate I'm going, I'm going to need a fuel tanker to follow me when I take long trips. I also have a non supercharged 96 Toyota Taco 3.4l with a 4" lift and 32's and I've never got below 16 miles to the gallon in that truck. If this Tundra can't be healed, the supercharger is getting pulled, the mileage re-evaluated, and the truck sold if the mileage doesn't improve. Any ideas or similar stories?

p.s, I've been an observer here for a long time and am a member of TundraSolutions, just not many Taco guys over there. I also just noticed this should be under engine/performance. If a moderator could move it, that would be great.


As for your question, no I use to get about 16-19 before I SC'ed. Now I get around 14-19 (14 when city driving and heavy on the skinny) I always owned cars, lowered, and sporty(aerodynamic) before. I never saw much of a variation due to high winds, but with truck the aerodynamics really kills our mileage. If you drive against high winds expect a major drop in mpg. As long mpg in "normal" driving condition is around 14-20 (auto) and 16-22(stick) you are in the ball park. That of course is with stock 31s and stock gears.
 

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Forgot about that.. It's an Xtended cab.. and I edited my post earlier to be a 5 spd. 4x4 as well.
 

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Are you running just the blower? URD? 7th inj?

Fuel tuning seems to be a must with the 5vz system. Im currently looking into 7inj tuning with URD's contoller or fuel Full URD kit with MI.

Couple of different options with most of the test subjects reporting 30-40hp with 17-20+mpg from what Ive read.
 

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TRDKEAU said:
Are you running just the blower? URD? 7th inj?

Fuel tuning seems to be a must with the 5vz system. Im currently looking into 7inj tuning with URD's contoller or fuel Full URD kit with MI.

Couple of different options with most of the test subjects reporting 30-40hp with 17-20+mpg from what Ive read.
I'm not running any fuel mods.. just the s/c and exhaust.
 

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well from reading your post.

the reason your loosing MPG is simple "BOOST" when u hit the SC it sprays almost double the amount of fuel u were using before. Also since u have a SC there is no lag like a turbo so when u need to pass somebody or get up to speed your using it more than u think cause SC is all about throtle positon. IM not real familar with the TRD SC but form my race car days and building fast forced inductinos and all motor cars I know that most aftermarket companys run the fuel mixture super rich when in boost so not only are u using the fuel u need for the extra air but your wasting some as well companys do this to save there ass and keep the cars in the safe zone ans also pass emissions etc.

The reason your MPG gallon when down even further with the lift is well now u are hight up and have more wind resitance and with bigger tires your now have more ratational mass to move and the motor has to work even harder and the more u have ot put your foot into it to get it moving the more the motor has to work and more the SC will being boosting and making that extra power for u.

THINGS TO CHECK
1) check your spark plugs if the truck is running real rich the plugs might be saturated in unburnt fuel and that can cause serious spark problems and poor combustion

2) Check your fuel injectors they could be faulty or stuck wide open

3) Your cats might be cooked from runnig rich and causing a major exhaust flow problem

4) Check to see if u have a faulty O2 sensor if the sensor sees something it does not like it can thow the ECU into safe mode causing it to run pig rich.

I guess in the end the saying still applys "If u want to play u have to pay" mabe if u regear

I hope mabe somehtign I posted will help u and u can get ot the bottom of the problem

-CHris
 

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Discussion Starter #9
Chris, thanks for the input and the same to all the others. I just received my URD kit today. I'm going to have it installed in the next week or so. Hopefully after some proper tuning, I'll gain back some of my losses. Brian at URD thought it was the fuel trims which are non adjustable. In speaking with my Toyota dealer, they said they could put it on the scope, but if there isn't a check engine light coming on, they most likely won't find anything.
 

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stock with the supercharger i got 18-24mpg on the highway, usually around 20mpg. after my lift and tires i get a little less, usually 17-19mpg hwy
 

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Triple BB said:
I'm going to post this here even though I'm writing about my Tundra since its a 3.4l motor issue. Specifically I've got a 4x4, 02 Tundra with 4000 original miles, 3.4l engine and a TRD supercharger. In short my gas mileage stinks. I drove to a dealer out of town about 2000 miles ago to have the unit put on. On the way up, the truck got 20 miles to the gallon. On the way back with the supercharger it got 22 miles to the gallon. I drove it around town for several hundred miles and didn't pay attention to the fuel economy. I then took a 500 mile road trip. I was shocked to only get 15 miles to the gallon on the way down and about the same on the way back. This was using the cruise control and travelling at the posted speed limit. I then added a lift and 285's. The mileage has since dropped to 13 miles per gallon. Last weekend I was driving into a 45-50 mile an hour head wind for 60 miles. I went and fueled up tonight and just about passed out. The truck was at 9 miles to the gallon. I recently ordered one of Gadget's URD kits to hopefully help the situaiton. I'm looking forward to installing it if Brian can figure out where he sent it. The question is, does anyone have an idea why my gas mileage took such a sharp drop after installing the supercharger? I can understand a drop with the bigger tires, but at the rate I'm going, I'm going to need a fuel tanker to follow me when I take long trips. I also have a non supercharged 96 Toyota Taco 3.4l with a 4" lift and 32's and I've never got below 16 miles to the gallon in that truck. If this Tundra can't be healed, the supercharger is getting pulled, the mileage re-evaluated, and the truck sold if the mileage doesn't improve. Any ideas or similar stories?

p.s, I've been an observer here for a long time and am a member of TundraSolutions, just not many Taco guys over there. I also just noticed this should be under engine/performance. If a moderator could move it, that would be great.

Your tires is the main reason for your decrease in mileage. You might want to regear. What kinda of tires do you have? I have an 03 tacoma 4x4. When i was stock with just supercharge i was getting 20 mpg on. Mileage stay the same after URD kit. I got a lift and metric 32' my mileage drop to 16 to 17. Mainly cause of really heavy MTR tires. Air pressure can be a key. Makesure to measure them first thing in the morning when its cold. Go by this psi. After you have been driving for a way even if its down the block, the tire pressure could increase by 8 to 10 psi. That was my mistake. I up the air pressure 32 in the front and 30 in the rear (cold), cleanrf my throttle body, poped in a new air filter now I'm getting 18-19 on freeways. 1 mpg isnt that bad with my tires. Good luck.
 
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