CAI + Axle Back Exhaust = Drop in MPG?
09-21-2013, 12:02 PM
#1
1st Gear Member
Thread Starter
Join Date: May 2013
Location: Nevada
Posts: 88
CAI + Axle Back Exhaust = Drop in MPG?
I installed a AIRAID CAI about 2 months ago on my new 2014 Mustang V6 and I noticed a little better throttle response and much better sound from it under the hood. Also noticed a slight bump (higher) MPG not much, but maybe 0.5MPG to 1MPG.
2 days ago, I installed an axle back exhaust (MBRP) and so far I really like the sound of it......but my MPG's have dropped about 1-2MPG. This is according to the digital readout on my dash that shows my fuel economy. Also noticed just a slight LOSS in throttle response......I assume its due to the reduced backpressure of the new axle backs.
I don't know if the computer needs to be reflashed or is this a common issue when freeing up more air......losing backpressure thru the exhaust system.
Anyone out there can share their own experiences with a CAI + Exhaust on a 3.7L V6 ???
2 days ago, I installed an axle back exhaust (MBRP) and so far I really like the sound of it......but my MPG's have dropped about 1-2MPG. This is according to the digital readout on my dash that shows my fuel economy. Also noticed just a slight LOSS in throttle response......I assume its due to the reduced backpressure of the new axle backs.
I don't know if the computer needs to be reflashed or is this a common issue when freeing up more air......losing backpressure thru the exhaust system.
Anyone out there can share their own experiences with a CAI + Exhaust on a 3.7L V6 ???
09-21-2013, 01:05 PM
#2
I'm averaging about 18mpg (mostly town driving) with my cai tune and roush axlebacks. I'm not sure if i saw a significant drop in mpg's with the axleback. Possibly .5-1 like you were saying. Not sure why as this doesn't consume more fuel. I didn't recieve a loss in throttle response, felt about the same. You may need a tune to compensate for any airflow gained/lost.
09-21-2013, 02:56 PM
#4
2nd Gear Member
Join Date: Mar 2012
Location: Texas
Posts: 417
Probably more to do with you liking the sound of your exhaust than it being less efficient. I averaged about 18 my first few tanks after I put on my Borlas. Now, I average 20-21 a tank.
However, any "canned" "custom" tune (Bama Brenspeed or otherwise) will not be the best tune. They take the manufacturer specs and extrapolate from that to build the tune. I recently went over that with Brenspeed Texas, trying to figure out what exactly I needed to do to get rid of this detonation issue. Turned out, hot weather and $hit fuel doesn't help. But eventually I will be getting a dyno tune to get the best setup for my area. Anything different from stock needs to be tuned professionally. Ford does alot of research to get a reliable* stock base. When we tweak it, we have to compensate for it.
However, any "canned" "custom" tune (Bama Brenspeed or otherwise) will not be the best tune. They take the manufacturer specs and extrapolate from that to build the tune. I recently went over that with Brenspeed Texas, trying to figure out what exactly I needed to do to get rid of this detonation issue. Turned out, hot weather and $hit fuel doesn't help. But eventually I will be getting a dyno tune to get the best setup for my area. Anything different from stock needs to be tuned professionally. Ford does alot of research to get a reliable* stock base. When we tweak it, we have to compensate for it.
09-21-2013, 04:09 PM
#5
6th Gear Member
How many dozen tanks of fuel have you gone thru? Yes, dozens. It usually takes at least a dozen data points (logging the avg. MPG then resetting the on-board at each fill-up IF you're not hand-calculating) to get a good idea of what your average is. You can't count on 3 or 4 or 6 fill-ups to tell you if something is affecting your gas mileage unless you're dragging a battleship anchor.
09-21-2013, 05:53 PM
#6
1st Gear Member
Thread Starter
Join Date: May 2013
Location: Nevada
Posts: 88
Nuke-
My dash screen readout has the AVE MPG and what I have noticed is that my normal driving was getting 18-19MPG (previous readings) with a high of 20MPG.......this is a CITY driving.
Now that my MBRP axle backs have been installed, the readout is showing 16-17MPG. Which is about 1-2MPG LOWER than before the axle backs.
I also have noticed I have to push the accelerator a little more to get the Mustang to GO. Again, I assume its due to the less restrictive exhaust and loss of backpressure. It's not bad, just "feels" different on the gas pedal. I think I am using more gas, due to the air/fuel mixture being off/different now.
Will a tune fix this? I wasn't planning to do a tune, but I will to fix this issue.
Or.......will disconnecting the battery and resetting the computer work?
My dash screen readout has the AVE MPG and what I have noticed is that my normal driving was getting 18-19MPG (previous readings) with a high of 20MPG.......this is a CITY driving.
Now that my MBRP axle backs have been installed, the readout is showing 16-17MPG. Which is about 1-2MPG LOWER than before the axle backs.
I also have noticed I have to push the accelerator a little more to get the Mustang to GO. Again, I assume its due to the less restrictive exhaust and loss of backpressure. It's not bad, just "feels" different on the gas pedal. I think I am using more gas, due to the air/fuel mixture being off/different now.
Will a tune fix this? I wasn't planning to do a tune, but I will to fix this issue.
Or.......will disconnecting the battery and resetting the computer work?
09-21-2013, 06:07 PM
#7
2nd Gear Member
Join Date: Feb 2013
Location: Texas
Posts: 308
I would go with the sound affect as well. My mileage dropped with a CAI and I had to fight to get it back up. Never did get it where it had been. With cool sounds come the desire to hear said cool sounds and that takes more gas. Also, I always calculate mileage. On-board computers are always a bit low.
09-22-2013, 02:29 PM
#9
6th Gear Member
A CAI without a tune? Why bother? You're likely running a bit lean but not enough to throw a code, nor enough for the PCM to make good use of the additional air. A tune will certainly provide a noticeable power gain. I don't know how the 3.7L responds to a PCM reset since I don't know if he has the adaptive learning and how to reset it like on the 4.6L.
The axlebacks should have ZERO affect on performance, despite the O.D. difference. You still have the OE pipe O.D. from the midpipes so that will be your limiting factor. The increase in O.D. at the axleback should have minimal impact such that no seat-off-the-pants impact is felt.
The axlebacks should have ZERO affect on performance, despite the O.D. difference. You still have the OE pipe O.D. from the midpipes so that will be your limiting factor. The increase in O.D. at the axleback should have minimal impact such that no seat-off-the-pants impact is felt.
09-23-2013, 07:31 AM
#10
A CAI without a tune? Why bother? You're likely running a bit lean but not enough to throw a code, nor enough for the PCM to make good use of the additional air. A tune will certainly provide a noticeable power gain. I don't know how the 3.7L responds to a PCM reset since I don't know if he has the adaptive learning and how to reset it like on the 4.6L.
The axlebacks should have ZERO affect on performance, despite the O.D. difference. You still have the OE pipe O.D. from the midpipes so that will be your limiting factor. The increase in O.D. at the axleback should have minimal impact such that no seat-off-the-pants impact is felt.
The axlebacks should have ZERO affect on performance, despite the O.D. difference. You still have the OE pipe O.D. from the midpipes so that will be your limiting factor. The increase in O.D. at the axleback should have minimal impact such that no seat-off-the-pants impact is felt.