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

[Gsxrdoug]

Did you do a battery unplug and let the truck reset itself? I had a tune went back to stock, truck ran like shit, unplugged battery now truck runs fine. I don't know why!

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[Dr3wDrop]

Strange both aftermarket mufflers had the same drop but miraculously after installing the oem muffler it went back up 5mpg.

 

[BiilyJones]

It's on cruise control for the tests I don't know how many times I gotta say it.

You must be pressing the set button really hard ?

 

[Gsxrdoug]

Maybe you need bigger turbos?

 

[Dr3wDrop]

Since I posted this I have
- Replaced the MBRP with a Borla S-type muffler (2.75in). No change in milage.
- Installed a Mishimoto Cold Air Intake kit. No change in milage.
- Gone through all 3 tunes provided by Unleashed Tuning. No meaningful change in milage (though the 91 Octane tune is great)
- Gone through FPP tune
- Gone back to stock

Is it possible that since you have gone through 2 aftermarket mufflers, CAI, and 4 aftermarket tunes in such a short time the truck has not had enough time to adjust its parameters resulting in poor milage? How many miles have you put on the truck since December.

 

[tehschkott]

Is it possible that since you have gone through 2 aftermarket mufflers, CIA, and 4 aftermarket tunes in such a short time the truck has not had enough time to adjust its parameters resulting in poor milage? How many miles have you put on the truck since December.

Maybe. I'm giving it a few days to a week between big changes for the past 2 months. I dunno.

I haven't done the battery disconnect/reset thing. Maybe I'll give that a whirl. Can't hurt.

 

[AzScorpion]

Maybe. I'm giving it a few days to a week between big changes for the past 2 months. I dunno.

I haven't done the battery disconnect/reset thing. Maybe I'll give that a whirl. Can't hurt.

A few days to a week isn't enough time for everything to adjust to the new mods especially a tune. When I flash a new tune it can sometimes take several fill ups (1K+ miles) for everything to smooth out. I would make a change and run it for a couple months and then see how you like it.

 

[tehschkott]

I concur there is benefit to keeping changes on there longer, let the system settle in. However it doesn't take a thousand miles / month to demonstrate meaningful behavioral changes, even with a tune. If it did our rigs would spend a lot more time in the mechanics. They're automobiles, not plants.

I put the MBRP muffler on and there was an immediately measurable outcome. I put the stock muffler back on and there was an immediately measurable outcome. There are immediately measurable outcomes loading the tunes as well.

There was an immediately measurable outcome putting the tailgate dampener on too.

 

[Dr3wDrop]

They're automobiles, not plants.

This is my favorite thing I have read in a minute.

 

[Ranger54]

I’m running FP tune, 33’s, MBRP exhaust, stock intake and I was at 18-19mpg summer but only able to get 16mpg in the winter. It is what is.

 

[Big Blue]

Maybe. I'm giving it a few days to a week between big changes for the past 2 months. I dunno.

I haven't done the battery disconnect/reset thing. Maybe I'll give that a whirl. Can't hurt.

How can you even figure what mileage your getting in a few days to a week?? That is crazy! Takes several tank fulls to get an accurate read. You've been making rapid fire changes and through the change over to winter gas. Anybodies guess what your mileage really is or what changed it.

 

[tehschkott]

Because I can do math?

Because there has been no observable model that gets worse before it gets better?

Things do change with time. They often start better and after a period settle back to being crappy. I make a change, I start logging, I get encouraging results. I continue to observe, continue to log, encouraging results come back down to being slightly more or less crappy again. So, when I state a given economy rating this isn't the outcome from a single point in time, it's the outcome of hundreds of miles of testing over several days/weeks sometimes. When I state economy has come up from 12mpg to 17mpg that's not a one-time drive of 60 miles. That figure is arrived at by driving 60 or 70 miles 5 or 6 times over a period of several days/weeks, all on the freeway, all using cruise pegged at 65mph.

Sometimes the data does improve. The stock muffler gave me 16.9, 17.4, and is now closer to 17.8mpg. Everything else about it is shit, but the fuel economy is there. But there has been no observable model that has gotten worse before it's gotten better. Which is not to say I pull the ripcord the second things turn, but if the trend is descending (or has descended) that says to me this is a dead end.

Because someone else asked, I've put 4,300 miles on the truck since December. I drive a lot.

 

[Big Blue]

Because I can do math?

Because there has been no observable model that gets worse before it gets better?

Things do change with time. They often start better and after a period settle back to being crappy. I make a change, I start logging, I get encouraging results. I continue to observe, continue to log, encouraging results come back down to being slightly more or less crappy again. So, when I state a given economy rating this isn't the outcome from a single point in time, it's the outcome of hundreds of miles of testing over several days/weeks sometimes. When I state economy has come up from 12mpg to 17mpg that's not a one-time drive of 60 miles. That figure is arrived at by driving 60 or 70 miles 5 or 6 times over a period of several days/weeks, all on the freeway, all using cruise pegged at 65mph.

Sometimes the data does improve. The stock muffler gave me 16.9, 17.4, and is now closer to 17.8mpg. Everything else about it is shit, but the fuel economy is there. But there has been no observable model that has gotten worse before it's gotten better. Which is not to say I pull the ripcord the second things turn, but if the trend is descending (or has descended) that says to me this is a dead end.

Because someone else asked, I've put 4,300 miles on the truck since December. I drive a lot.

Whoa! Sorry ment no offense to you math skills. Or the amount of miles you drive.

The problem with your method I see is calculating mileage in 60 to 70 mile chunks. That is only 3 to 4 gallons. The variability in fillups that small is statistally significant, as are the variabilities in traffic, weather,etc. The variable that go into gas mileage are soany trying to determine an accurate number from such small chunks is impossible much less a change trend.

Believe what you believe but you are dealing with looks like very noisy data.

 

[tehschkott]

Best I can say is the route is flatish, I choose times to drive it during low traffic periods and interruptions are low. And I supplement with alternate less controlled tracks that reflect similar controls - and predictably return similar findings. Some of them are significantly longer. A drive to Spokane is 223 miles each way and about 4ish hours for example. The data is a little noisy but I'm able to generate a lot of it and extract reasonable and comparable values. Short of being on a closed track I don't know what much more can be done.

 

[Trigganometry]

I concur there is benefit to keeping changes on there longer, let the system settle in. However it doesn't take a thousand miles / month to demonstrate meaningful behavioral changes, even with a tune. If it did our rigs would spend a lot more time in the mechanics. They're automobiles, not plants.

I put the MBRP muffler on and there was an immediately measurable outcome. I put the stock muffler back on and there was an immediately measurable outcome. There are immediately measurable outcomes loading the tunes as well.

There was an immediately measurable outcome putting the tailgate dampener on too.

The root of your problems is… doesn’t allow flex ?? just stab on that skinny pedal

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