MD1

Question for you all:

I drive a 2011 Mustang V6 (manual) and recently had a tune and CAI put on it. The issue is, my MPG have decreased to 16MPG from 18MPG. Is this something i should be concerned about? Shouldn't i be in the 20's?

I don't granny the car, but nor do i drive it like a bat out of hell.

Any suggestions or should i keep my foot planted in second just a few more times?

SONICBOOST

Its the gas pedal being floored thats giving you less MPG!! HA Typically a CAI/Tune should give you more MPG if you are driving your car the same as before..

freyke

I don't see how a tune would necessarily provide better mileage; typically it will tend to richen the fuel/air mixure and if anything decrease mileage slightly. Even if the mileage did increase it usally comes at the expense of one being required to increase octane (which costs more $$). Most production tunes are designed to run the vehicle as lean a practicly posssible without causing damage. (lean = hot; rich = cool).

I'm just say'n sometimes a tune ain't all it's cracked up to be - everything has its up side and its down side; there are no free lunches.

eliyarbrough

If I was getting that in my 5.0, I'd be worried! Saying you should be. I'd take it in.

orgchem

I don't know about that. I consistently get lower than 16 mpg in my 5.0 . For the 3.7, 16 mpg seems a little odd unless you are driving it pretty hard.

eliyarbrough

I do too. I was just thinking this was on hwy. Don't have much knowledge of anything, so trying to use my common sense.

freyke

I'm averaging 16.7MPG in my 5.0 MT w/3.73s. For comparison my '07 LS2 Corvette (traded in on the 11 Mustang) averaged 17.8MPG.

jlmounce

Actually, if you've ever seen the AFR's on a factory engine they are usually quite rich. In some cases close to 10:1 in the upper rpms. It's a safety net so Ford doesn't have to replace engines due to burned pistons.

Most if not all proper tunes will lean the engine out. Most tuners command AFR's in the 12-12.5:1 range on a normally aspirated engine under 100% load.

During normal driving, the vehicle is using it's onboard sensors to monitor AFR real-time and provide as close to stoiche as possible. Generally that.s 14.7:1

If the brunt of your driving is done in partial throttle where you never enter the table based operation realistically, you shouldn't notice any difference in fuel mileage before and after. However if you've got a heavy foot, with an intake and tune you may actually see an increase in fuel mileage.

To the OP, if you just put that system on, give it a little bit of time. You're foot is probably a bit heavier than it was with the new found power and throttle response. Give it a couple tanks so that you get used to the car again, then check the mileage. Also, you should be checking mileage by calculating actual fuel usage at the pump. You shouldn't rely on the factory rear-out as it's a lifetime average until you reset it.

jacostang

My last recording in my 11GT W/373 was 20.4 mpg, normal driving with less than 2000 miles on the clock...

Ltngdrvr

OP, your fuel economy is all in your driving style.

You say you don't granny it and there in lies the poor fuel economy.

You have to drive it as lightly as possible, accelerate very slowly, short shift to get to as high a gear as it will pull at as low a speed as possible. Anticipate your stops and coast down in gear to slow down instead of rushing to the stop and tromping the brake pedal.

It's not the fun way but it's the way to get the best economy.

freyke

You must be feather-light on the throttle!

MD1

Thanks for all the replies, guys. I just got the car tuned, which meant the avg. mpg was reset; however, the good old divide the total miles driven/number of gallons in the tank don't lie...16MPG in a V6...ouch.

I should go to confession.

eliyarbrough

In my auto 5.0/3.15's, when I fill up I get about 19.5 MPG. I don't granny mine, but pretty close. I never speed, but get up to the speed limit pretty quickly. I just set cruise & go, don't coast I mean.

CO_VaporGT_09

If you truly don't drive it any differently before/after the CAI and tune, you should see increased mileage, as it would require less throttle to generate the same acceleration as before (minor differences, but should still be evident), leading to less fuel usage.

In reality, most people use the throttle much MORE after the CAI and tune for reasons mentioned above, so could see a more distinct drop in mileage.

Truly baby it for the next tank and see how it does -- it's hard to resist, though, so some valium might help.

Modshack

The tune has changed timing and fuel injector frequency. More power takes more fuel. There is no free lunch..

CO_VaporGT_09

Sure there is -- it's called welfare

The free lunch here is, if you accelerate at the EXACT same rate, you should have to use LESS throttle, as more throttle, more gas, more acceleration, right? Same argument as for steady-state cruising -- less throttle to maintain against the drag, rolling resistance, etc, as you're making a bit more power from the tune and CAI. So theoretically, you can gain MPG from using these pieces, but only if you don't drive any differently.

freyke

KonaBlue5.0

That certainly isn't true for me. I typically see 20-22mpg or more in the '11 GT, and the claw marks on the sides of the passenger seat agree, I'm definitely not gentle on the loud pedal..

danimal15

I've been seeing 15-16 in my 2011 GT with MT, and I don't drive like a granny or like a maniac, either. It's all city driving, however.

I recently took it on the highway for the first time in months and managed to get 27 MPG over a 20-mile stretch, which I was very happy about, but I was driving mostly in sixth gear.

danimal15

I'll add that with gas at $4.25 a gallon around here (Chicago) I've only been driving the GT about once a week and mostly am driving the Prius to enjoy the 44 MPG I typically get.