Wrong MPG and Range after Cold Air Intake and Muffler Install

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giganova

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Hi all --

After installing a K&N 77 cold air intake and a Flowmaster Outlaw muffler, my 2021 RAM 1500 5.6l/V8 gives me wrong mpg and range readings:

- Before install: 19 mpg over the past 7,000 miles, 450 miles range (mostly highway and with the 33 gallon tank). I confirmed that these numbers are correct by counting miles when I gas up.
- After install: 13 mpg, 300 miles range

I had the battery disconnected before the install, assuming the computer would automatically reset and calibrate.

Any suggested solution?
Thanks!
 
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Dean2

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Hand calculate your mileage. I have seen K&N cold air kits mess up the gas mileage on more than a few vehicles. If you flow more air, you burn more gas to keep the right mixture. No way to avoid that. Also, flowing more air means you aren't filtering near as well. K&N claims better filtration but it has been proven false many times. Don't know how they have never been wacked by regulators. If you use the truck in dusty environment I strongly suggest you go back to a stock paper filter.
 

IDSandman

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Solutions? Yeah. Dump that useless K&N and go back to the stock intake. The K&N is useless and offers zero benefit over the stock one. Not just my opinion. It has been proven over and over on dyno’s as well as this forum.
 

crazykid1994

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Stock air box is definitely better and colder air than k&n which colder air makes more power more efficiently than more air that’s warmer. Warmer air reduces power and reduces fuel economy because the engine works harder to do the same job. I added a snorkel to my truck and actually noticed my mpg went up almost 1mpg. My intake temps stay a bit lower for the most part. Unless in stop and go traffic because of heat soak in the engine bay. I’m trying to figure out how to lower engine bay temps in my truck to reduce heat soak.
 

PoMansRam

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Has it been several fill-ups and the fuel economy drop is still evident?

If it's your first tank or two, the reduced fuel economy is probably from you making your new toys make noise, which is all that CAI and loud muffler are going to do for you. I've been there. LOL
 

Scottly

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You don't have reduced fuel economy. You have reduced information for the system to calculate those numbers, based on the fact that you erased it all by disconnecting the battery. While I agree the K&N was a waste of time and money for a stock engine, it won't cause what you describe. Drive it for a week or two and report back.
 
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giganova

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The K&N install instructions said you need to disconnect the battery, that's why I did it.

I'll keep an eye on mileage for the next few tank fills. maybe it'll go back to normal (which I doubt because now even my Trip B -- which is total mileage since I bought the truck -- is also down to 13 mpg). But in any case, lets see if it changes over the coming weeks.
 

Tray Burge

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I'd dump the K&N hot air sucker too, actually I did the day I got mine home.
The "Vararam" is the only one with dyno proven results and is the only way to go.
IMG_1547.JPG
 

IDSandman

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Hopefully the op listens to every post on here and sells that worthless K$N amd goes back to stock. Doesn’t look like it though. Oh well, lead a horse and all that…
 
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Hopefully the op listens to every post on here and sells that worthless K$N amd goes back to stock. Doesn’t look like it though. Oh well, lead a horse and all that…
Cold air intakes are useless like everyone else has posted before me, these cold air intakes can actually cause more harm and never any good .... stay with stock OP !!
 

GTyankee

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spraying even a light coat of oil on a paper filter, may catch more dirt, but it also restricts the flow of air

2 chamber mufflers are better than 3 chamber mufflers & they are louder too

Under Hood HEAT SOAK ??
What happens when you block the radiator with cardboard or say, Rams favorite piece of crap, the AGS.
No air flowing through the radiator, means no hot air being disbursed from under the hood.
That is great when it is around 50°F outside, BUT when the Temp is 90°F outdoors, you have to begin noticing less MPG & other fuel eaters.

You might try venting the pressure under the hood

( allow hot air in the engine bay to escape outside )
 
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giganova

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No, I am not gonna dump the K&N. I know you all mean well, but the question I have posted was not about the benefits of a CAI, it was about wrong mileage readings. ;-)
 

crazykid1994

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No, I am not gonna dump the K&N. I know you all mean well, but the question I have posted was not about the benefits of a CAI, it was about wrong mileage readings. ;-)
Have you hand calculated a tank of gas yet to see if it’s actually off? Computer for me is roughly 1-1.5 mpg off from actual
 

huntergreen

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No, I am not gonna dump the K&N. I know you all mean well, but the question I have posted was not about the benefits of a CAI, it was about wrong mileage readings. ;-)
No, I have not heard of a cai messing with the computer readout.
I think Pomanram post 5 nailed your issue. One way to check is remove the cai for a couple tanks of gas and see if mileage goes back to normal.
 
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Ram1958

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The K&N install instructions said you need to disconnect the battery, that's why I did it.

I'll keep an eye on mileage for the next few tank fills. maybe it'll go back to normal (which I doubt because now even my Trip B -- which is total mileage since I bought the truck -- is also down to 13 mpg). But in any case, lets see if it changes over the coming weeks.
I have seen instructions for changing a Rad Cap say Disconnect battery. Many instruction sheets read " Disconnect battery before working around engine".
 

Ram1958

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Hi all --

After installing a K&N 77 cold air intake and a Flowmaster Outlaw muffler, my 2021 RAM 1500 5.6l/V8 gives me wrong mpg and range readings:

- Before install: 19 mpg over the past 7,000 miles, 450 miles range (mostly highway and with the 33 gallon tank). I confirmed that these numbers are correct by counting miles when I gas up.
- After install: 13 mpg, 300 miles range

I had the battery disconnected before the install, assuming the computer would automatically reset and calibrate.

Any suggested solution?
Thanks!
First problem is with K&N your pulling from engine bay which is hotter than what stock brings from outside. Second is If you do not pre filter that K&N you are feeding your engine more contaminates(dirt). Ditch the K&N.
 

zogg

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If you read all of the k&n advertising, it says:”During dynamometer testing, the 63-1578 provided an estimated power increase of 10.7-horsepower and 15.5 lb./ft. of torque”

The 5.7 Hemi is rated at 395 hp and 400+ pounds of torque. I can’t imagine that I could tell the difference with a k&n or any cai. Not with a ~2% increase.

K&n used to show a power graph and it showed the power increase starting around 4,000 rpm, so absolutely NO INCREASE in normal driving. Who the he!! Drives around daily at 4,000 rpm’s? Also, since so many folks noticed this, they removed it from their advertising.

They also indicate that the K&n filter flows far better then the oem on a flow bench….and it does because it allows air, bugs, dirt and dust thru the filter element. Less restrictions.

I was ASE certified until I retired and I’ll note that any computerized engine today will only take in the amount of air needed for efficient mix with the fuel provided by the injectors, which are also computer controlled. So, if you remove the filter element completely the computer will NOT TAKE IN ANY MORE AIR.

I know that some folks swear that there is a big “seat of the pants” power increase and also a corresponding mpg increase. I attribute this to the fact that they have disconnected the battery for cai installation and the computer is in process of resetting itself. After 2 or 3 heat cycles the computer goes right back to where it was.

Finally, I put a USAF veteran sticker on my back window and I now get 4 more mpg and 12 more hp. I’ll sell you my sticker for the price of the K&n. Haha
 

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