So I got a T1R B-Max Intake, sounds great, definite performance gain, love it!
I did the Idle relearn after installing it, but after being on for half an hour the fan didn't come on at all so I hope that's not part of my problem, it does seem to be running fine.

What I don't love is the drop to an AWFUL 25MPG from my average 35.5MPG so far (I have a Sport AT with 1500 Miles).

I have been driving the same, minus 3-4 times flooring it to test out the new intake.
The only difference that could have caused this MPG change that I can think of, other than the intake, is that right before I installed it I filled up on 87.

I know everyone is going to argue about this, but I usually use 94+Octane booster which costs me around $1.00/gal. because my dad works for sunoco and our whole family gets a flat discount, so I don't care about the extra cost involved with the higher octane.

A few of my friends with stick shift Fits use high octane too, and compared to any other gas, they consistently get 3-6MPG more with it, findings made on very consistent calculated and scangauged testing.
So, I am wondering if it's the low octane that I started using all of the sudden, or the new intake, or both.

My understanding with the intake is that more air, more gas = better performance and less fuel economy, right?

I didn't think it would be this drastic, is there any other factors I should take into account that could have caused this change in fuel economy?

My Fit is pretty standard other than the intake and dead pedal, but I'll take some pictures today anyway.

Thanks for your input guys.

 

If the intake is sucking in a lot more air, the ECU is going to send a lot more fuel, I would think...

 

Not sure why your fuel mileage changed so drastically, mine didnt' change at all when I installed the T1R intake on my car.

 

Your car may be adjusting to the lower octane levels as well since you were running 94 plus an octane booster. The fit was built to run 87, anything more will cause it to run rich, so you may have an issue with fouled plugs that you hadn't noticed till you switched back to 87.

 

I'm at 270 miles on this tank, about 5 miles from actually being empty, so I'm going to fill up with 94+Booster again and see if it goes back.

yeamans17, Do you really think my plugs, after 4 or 5 fillups since I bought the car, are fouled up from high octane? Why do my friends' Fit's consistently get better MPG with high octane? Do you really think a second fill up of 87 will yield closer to my old MPG rather than going back to premium?

 

I didn't realize you've only used it a few times, personally I wouldn't run it, not unless I was boosted. Also did you change up distances you were driving? With my Fit I manage 32-35 as my dd driving 6 miles to work, and 6 back home, but when I step it up and drive further distances or hop on the highway my mileage increases drastically.

 

I have a 26 mile round trip daily commute to work 3 days a week and 10 mile round trip commute to school 2 days a week, that's my consistent weekly commute driving, other driving is fairly consistent.

I fill up with less than 0.5 gallons remaining usually, calculating my mileage by dividing my trip odomeder when the gas light comes on by 9.1 which is the amount of fuel consumed before it comes on, then multiplying my resulting MPG (1.7gal remaining at that point) by 10.8.

I calculate again when I fill up the usual way and it matches my odometer method very very closely.

For example:
232.7 miles on Odometer when light came on.
Divide by 9.1 = 25.58mpg
Multiply by 10.8 = 276.2 miles = Empty

It's not the most accurate as mileage varies all the time, but scangauges are too expensive for me.

I bought this car outright with all-season mats and urethane polycarbonate front end invisible bra and for only $17,142 out the door including all fees, taxes, etc., a figure I am very proud of, the result from negotiating with 20 or so dealers. No I'm not kidding, and yes it's a 2008 Fit Sport w/ Automatic, and came with 0 miles and plastic wrap included. It should have cost me 19,061 with the mats and bra.

 

i actually got more mpg. im driving a AT.

 

Ditto... I got an increase in mpg as well. Mine is a 5MT tho, but if you drive normal and dont floor it, you will/should see an increase.

 

i too increased in my mileage. And i am in automatic as well. My work is 26 mile roundtrip 5 days a week and even with a/c on all the time (vegas can be hot) I have not got below 30mpg since i installed my intake.

 

My mileage came out to 26.2 at the pump. Back to 94+Octane booster, I'll update my MPG when I fill up again, I have a feeling it was the gas.

 

Not a chance in he** that increased octane will cause the FIT to run rich. And no fouling plugs either. Any changes at the ECU happen instantly and only would involve adjustment to the timing ONLY IF THE KNOCK SENSOR DETECTS PINGS. No other "adjusting" involved especially running rich.

 

sounds like you just driving it hadrer

 

I am with most people on what they are saying. Use 87, don't drive like it is a race car and you too can get well above 40mpg.

 

stop whining
get your 300 bucks back

end of thread

 

your going to ruin your engine running on 97 with octane booster... car was designed to run on 87... anything else is just money out of your wallet... higher octane does not produce more HP period!

 

I don't notice or fill up with high octane for HP, I just use whatever gets me the best MPG.

These results below are my fuel economy figures:

Dual-calculated based on:

1. The gallons filled divided by trip
2. By the low gas light (which equals 1.7gal. remaining)
   divide trip by 9.1 (gallons remaining)

The figures from both methods always come out to be about the same as each other for me.

1. 27MPG / 87 octane - First Fill from dealer I bought the Fit at
2. 35MPG / 95 octane - Sunoco & Boost
3. 27MPG / 87 octane - Sunoco
4. 37MPG / 95 octane - Sunoco & Boost
5. 26MPG / 87 octane - Sunoco + Installed Intake
6. NA/NA / 95 octane - Sunoco & Boost - Just filled up.

 

... why do you keep switching back and forth. I would just run 87. Chances are if they built the car to run on 87 it should probably run on 87.

I don't think the type of gas or the intake would make a matter of 10mpg difference. I think it is probably the way you are driving.

 

BS a 10 mpg increase just by using different octane ????? If that were the case Honda would just tell everybody to use 95 and they could advertise the latest and greatest increase in MPG ever just by running 95 octane GIANT BS

 

this just in!!!!!! the AT sucks .... air :P