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I added a supercharger to my 2017 Toyota Tundra. She’s named The Fundra for all the adventures we were going to go on. Before supercharger I was getting around 15 mpg. After it dropped to about 12.5.

Now, I’m down to 10.4. I towed my boat 70 miles round trip and it dropped to 7.8 mpg.

it was installed my a master technician atToyota store. I’m getting good gas, not gunning it but it just doesn’t seem like I should be getting that low off of everything I’m reading.
I put a new battery in it last year and then it went back up to 12.5 and then it’s dropped again to 10.3-10.5 again.
Help! I want to take my Fundra but don’t want to go bankrupt on 7.5 mpg!

thanks all.
 

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My mileage went up no less than five miles per gallon average. I just completed a round trip from Chico Ca to Reno Nv. Via two lane back roads And back with an elevation gain of over 5000 ft. There are many ups and downs along the way .This included passing with one blast over 125 mph. And I still averaged 20 mpg. Without the supercharger my average was 14 mpg .
 

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If it is feeling sluggish while getting the poor mileage, make sure the vacuum line from the diaphragm down to the housing on the front of the supercharger is not leaking. I wound up placing hose clamps on mine and made sure the actuator is moving freely. I sprayed a little grease on the rod where it enters the housing. For me this was not allowing proper boost and mileage suffered but so did performance.
 

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Discussion Starter #4
If it is feeling sluggish while getting the poor mileage, make sure the vacuum line from the diaphragm down to the housing on the front of the supercharger is not leaking. I wound up placing hose clamps on mine and made sure the actuator is moving freely. I sprayed a little grease on the rod where it enters the housing. For me this was not allowing proper boost and mileage suffered but so did performance.
Awesome. I will check that out in the morning. I just don’t understand. I am thinking maybe the bullydog isn’t giving the right info?
 

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I have HP. My neighbor has the older TRD tune at 505 hp. Which was not a download. It was drive it like you stole it and the computer would learn. He also said he gets 22 on open flat highway at about 70 mph, I see the same or better. He also said you need to change spark plugs at about 50,000. He changed his at 85,000 said the electrodes on 3 plugs were missing.
 

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What octane are you running?
 

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A supercharger by definition is always pumping air into the engine, and you have to maintain the air to fuel ratio, and it does use some power to spin, so you are always pushing more air and fuel through the engine, so you should gain HP and lose some MPG's. 12.5 mpg is about what I would guess.

On the other hand, I bet the pedal is a lot more fun to push!!!
 

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A supercharger by definition is always pumping air into the engine, and you have to maintain the air to fuel ratio, and it does use some power to spin, so you are always pushing more air and fuel through the engine, so you should gain HP and lose some MPG's. 12.5 mpg is about what I would guess.

On the other hand, I bet the pedal is a lot more fun to push!!!
I wish I had a supercharger and until I get one I would never assume MPG would go up whatsoever by getting one. I totally agree with your post, superchargers unlike turbos add power from idle all the way up the RPMs thus requiring more fuel at all levels of RPM also AFR is required to be richer so I don't see how anyone is assuming they are getting better MPG after adding a supercharger. Unless they are trusting the computer and dash readout and not utilizing actual miles driven versus gallons used. I have a twin turbo Trans Am which gets great mileage at idle and cruise, but when I slam the gas pedal I can get as low as 4-7MPG. You can actually watch the fuel level needle move towards E...
 

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Also, check what is required for octane for the gas you use. A super charger might require high octane, but don't use any higher octane than they recommend. A lower octane fuel will get better mileage than a high octane fuel because it is more explosive. But you might need the higher octane to prevent pre-ignition due to the higher cylinder pressure from the supercharger. Run the lowest octane you can. Also, use the lowest % ethanol you can get. The ethanol reduces mileage.

You also might try changing to Mobil 1 0-20 advanced fuel economy. I use that in my 2015 5.7L CM and average about 17.5 MPG. If I don't use the Mobil 1, I am in the 15.5-16 MPG range so it is good for 1-1.5 MPG increase.
 

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Are you also taking into account the reset of the mpg every time you remove the negative to battery? I have done many upgrades to my 2017 and each time it starts out saying 20 - 25 mpg on dash but after 2 or 3 tanks it go’s back to the real thing of 9 to 11 mpg and I have not put in a supercharger yet!
882803
 

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I wish I had a supercharger and until I get one I would never assume MPG would go up whatsoever by getting one. I totally agree with your post, superchargers unlike turbos add power from idle all the way up the RPMs thus requiring more fuel at all levels of RPM also AFR is required to be richer so I don't see how anyone is assuming they are getting better MPG after adding a supercharger. Unless they are trusting the computer and dash readout and not utilizing actual miles driven versus gallons used. I have a twin turbo Trans Am which gets great mileage at idle and cruise, but when I slam the gas pedal I can get as low as 4-7MPG. You can actually watch the fuel level needle move towards E...
Just to be clear, I am not assuming I am getting better mileage I actually am getting what I quoted above without the trailer attached. With the trailer attached it gets right at 3.5 MPG better than prior to the supercharger. It does require 91 octane. Even the small family owned gas station I use has noticed I do not stop by as frequently any more and asked why. I told them I am averaging 100 miles more per tank full so I don't need to stop as often.
 
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