Big MPG hit after MBRP exhaust install, looking at new tune

[Porpoise Hork]

Something else caused such a drastic drop in efficiency.

Yeah..

Something else...

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[Dr. Zaius]

Yeah..

Something else...

 

[E Monty]

Livernois and MBRP cat back here increased my stock set up. About 25 summer and low 20’s/high teens in winter. Lower MPGs make no sense.

 

[Langwilliams]

wouldn't an exhaust change be within the learning capability of the tune? I installed a Borla muffler but not a complete system then ordered my tune from Livernois. I noted it in the order. Since I installed the tune I added a high flow air filter an the smooth flow air tube from the airbox to the intake. I didn't notice a change with that.

 

[Frenchy]

I just installed a MBRP exhaust and my MPG dropped from 16.6 to 14.6 - which I have a problem with. I have the FPP tune and have had it for 12+ months or so and I like it a lot. I assume the exhaust is throwing things off and mucking with my MPG. I'm thinking about changing up the tune.

I'm angling towards

• Unleashed Tuning
• 5 Star tuning
• Livernois tuning

QUESTIONS
1. Do any of these tunes provided by the above vendors require keeping the tuner plugged in?
2. What is the most supported tuning appliance/programmer? I'm angling towards

• SCT/Bully Dog BDX
• SCT/ X4

I don't want to keep having to buy programmers between vendors and it looks like I don't have to if I pick the right programmer appliance.

--

Other data

I'm not drag racing but I drive the piss out of my truck, on highway and offroad both. I put 29,000 miles on my truck in the first year of owning it and I expect to do the same next year.

I'm on 33in tires and have a small lightweight camper (think Go Fast Camper) which has added some weight and air drag. The 16.6mpg I was getting is WITH the camper on it (I dropped from 17.6 mpg putting it on).

I always run highest grade fuel available from the pump - usually between 91~93 octane.

I'm soliciting input on tunes, and programmers. Your input widely welcomed.

--------------
Frenchy, your feelings about 5 Star have been noted. The rest of you shut up about his feelings. If you have some data to debate 5 Star, great. I don't care if "he always does this with X".

Thanks in advance.

So.in all honesty a cat back exhaust wouldn't cause less MPG unless you really like the sound and you happen to be laying into it a but more than normal(yes that's common nomatter what the vehicle). As for your set up is it safe to assume you have a Leveling kit? Just curious on that one.

As for the tune its hard to say if going to a different company will actually benefit. Dont get me wrong I like the Tow tune from Livernois and it would do you better over the Performance tune due to load but there isnt much of a power difference between that and the Ford Performance Tune. Also if not mistaken since you already have the ProCal4 wich is basically the same as the my touch calibrator you may be able to get the tunes from Livernois a little cheaper since you already have a compatible module(contact Livernois to verify that one).

 

[tehschkott]

Yep must be the exhaust. couldn't possibly have anything to do with the tune, the 33s, the off-road driving, the camper, or the lead foot..

I'd say you are probably doing as good as you can do. Your asking alot of the truck to return you 17+ mpg.

What do you want, the bloody fuel logs? The FPP tune, the lift, the 33in tires have already on there for upwards of a year. Was getting 17.6 mpg pretty steadily.

I put the camper on. Drove 1000 miles with ACC cruise on the the lions share. Mpg dropped to 16.6. Okay. No surprises

I put the exhaust on and I immediately drop into 14.5 mpg.

 

[tehschkott]

So.in all honesty a cat back exhaust wouldn't cause less MPG unless you really like the sound and you happen to be laying into it a but more than normal(yes that's common nomatter what the vehicle). As for your set up is it safe to assume you have a Leveling kit? Just curious on that one.

As for the tune its hard to say if going to a different company will actually benefit. Dont get me wrong I like the Tow tune from Livernois and it would do you better over the Performance tune due to load but there isnt much of a power difference between that and the Ford Performance Tune. Also if not mistaken since you already have the ProCal4 wich is basically the same as the my touch calibrator you may be able to get the tunes from Livernois a little cheaper since you already have a compatible module(contact Livernois to verify that one).

Noted. Yeah, I'm as surprised as anyone. I'm not really stomping on it. The factory muffler started leaking so I replaced it with one that was better performing. I mean, maybe it does spool up a bit faster, if so I can't tell. I punch in the ACC as soon as I'm able and ride it out.

I think I will hit up Livernois, thanks for the 2c.

 

[tehschkott]

And for record, I don't like the louder exhaust. I'm definitely not stomping on it to hear it. I come from poor people. When you're poor, all your mufflers are loud because you can't afford to to anything with them but let them rust out. I don't like the louder tone, and I'm not going for it. Maybe the rest of you are 24 and happy to burn it down, I'm a 45 year old Army Infantry vet. I'm not aiming to burn anything down with this rig.

I do not know why the MPG tanked because of the exhaust, you're right, all logic to the contrary suggested to me MPG should have improved. That's why I'm here. Thanks for your genuine input, those who offer it.

 

[LB357]

Spitballing here, could a change in the winter fuel mix at the pump have caused it and it just been coincidental? Not sure where you're located if this even applies. I installed the MBRP turndown catback this weekend and am running 265/70r18 on stock suspension with the Livernois tunes so time will tell if I run into a similar scenario. That being said, I also only ran the 87-89 tune for about a half tank before switching yesterday to the 91-93 tune and filling up with premium so I don't exactly have a baseline I can judge from but will say the truck seems to "breathe" easier with the new exhaust.

 

[puckdodger]

Unleashed 91 performance and daily tow here, very happy with it. BDX hardware

 

[OCL]

Maybe the rest of you are 24 and happy to burn it down, I'm a 45 year old Army Infantry vet. I'm not

I'm older than you.

I think the gist of the message here is your mileage should not have come down. It should have improved. Because it went down suggests there's something else that's causing it. So I would simply suggest you go through the process of elimination. Eliminate all possibilities and you are left with the truth. The one truth we know of is a cat back exhaust system should increase fuel efficiency.

Winds and constant load on the engine, such as a slight uphill for long periods, can easily bring your MPG down. Tire pressure can also affect it. Dragging brakes maybe? Added weight in the bed? The MBRP is a cat back, so your engine's ECM is reading exhaust gas Oxygen levels from upstream of that aftermarket exhaust. So theoretically, it won't affect the ECM fuel/spark programming all that much. The exhaust gas is simply moving out faster, which means your engine should actually become more efficient at taking in and burning a fresh inhale of air and fuel because there's less residual burned exhaust. Having said that, an exhaust leak somewhere could easily decrease your fuel efficiency.

Check all exhaust bolts on the new MBRP and they're tight? Was there an exhaust gasket back there that should have been replaced?

Don't get mad. Solve the problem. A new tune probably isn't the right answer.

 

[tehschkott]

an exhaust leak somewhere could easily decrease your fuel efficiency.

I think if you read through my post and responses you'll see I literally laid out the controls and the conditions. I can draw a direct line between changing the exhaust, and the drastic reduction in milage. There is no other factor. You are the first, in that sentence, to provide some thought behind why/how changing the exhaust might result in reduced mpg.

I'll go back through and check the install. I would love for that to be the answer. Thanks.

 

[SICKQK]

And for record, I don't like the louder exhaust. I'm definitely not stomping on it to hear it. I come from poor people. When you're poor, all your mufflers are loud because you can't afford to to anything with them but let them rust out. I don't like the louder tone, and I'm not going for it. Maybe the rest of you are 24 and happy to burn it down, I'm a 45 year old Army Infantry vet. I'm not aiming to burn anything down with this rig.

I do not know why the MPG tanked because of the exhaust, you're right, all logic to the contrary suggested to me MPG should have improved. That's why I'm here. Thanks for your genuine input, those who offer it.

Is there "winter blend " fuel where you live?

It will cause a 5-10% reduction in fuel economy in my experience. Happens every year.

 

[tehschkott]

Is there "winter blend " fuel where you live?

It will cause a 5-10% reduction in fuel economy in my experience. Happens every year.

I think so. Last year I got caught by that. But that 1. flips over in Sept and it's Dec now. And 2. This change - the muffler upgrade - happened mid tank.

 

[tehschkott]

I solved it.

I unloaded my FPP tune, went back to stock. Drove it around for better part of an hour, came home, reloaded FPP tune. Drove it for another hour - mostly using ACC cruise. MPG is now back to 17.4mpg at avg 70mph.

To recap

Drove to California - 800 miles - empty truck 17.6 mpg.
(expected baseline)

Put camper on, drove home 800 miles - 16.6 mpg
(expected, added weight and drag, etc)

Got home, replaced muffler with 3in MBRP cat back single port exhaust - 14.5 mpg
(Uh, WTF is going on)

Took tune to stock, drove around, reloaded FPP tune, drove around - 17.4 mpg

So this is great. Mpg is back to expected levels, in fact it's actually better than expected since my new baseline with the camper was 16.6 mpg. 17.4 mpg is better than I expected. There's been no change in fueling or anything else (there was a tank refill after the exhaust to see if that would change the milage - it didn't). The only thing changed was reloading the tune.

Muffler also sounds different, it's less blatty.

Now, I don't have insight into the inner workings of the truck, I don't know what the truck computer can adjust to or how the tune is applied, so I could be full of crap. But my theory is by returning it to stock and driving it for a bit the computer recalibrated with the new muffler. Later when reapplying the FPP tune to the freshly recalibrated truck, everything clicked together properly like it should.

In any case I'm fixed now. Thanks for the input.

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