Added just K&N Filter

speeddemonxp97 · Dec 7, 2016

I added a K&N filter (not a full CAI) 2 weeks ago and since then my MPGs seem to have dropped when the truck goes into "ECO" it doesn't seem to climb into the mid 20s like it used to.

Why would a better flowing filter cause this?

Hemi450hp · Dec 7, 2016

K&N filters are not necessarily better flowing filters. The drop in mileage could also simply be because of the cooler weather and winter blend fuel. Cooler air is denser air which will use more fuel.

Kotta390 · Dec 8, 2016

speeddemonxp97 said:
I added a K&N filter (not a full CAI) 2 weeks ago and since then my MPGs seem to have dropped when the truck goes into "ECO" it doesn't seem to climb into the mid 20s like it used to.

Why would a better flowing filter cause this?

Short answer is no. The factory air filter setup is free flowing enough driving around unless it was clogged with dirt.

Hootbro · Dec 8, 2016

This is a prime example why CAI or just air filter alone mods without a tune are 99.9% of the time a waste.

Stock programing is going to adjust the fuel trim to a predetermined fuel/air ratio by programing. Modify the air intake and the fuel trim just adjusts to compensate.

Most claims of gains by a air intake only mod with no tune, are usually short lived until the vehicle's adaptive mapping for the fuel trim readjusts trying to bring bake the fuel/air ratio to factory parameters settle in.

NJ'12HemiExpress · Dec 8, 2016

I just purchased a K&N myself and should be receiving early next week. My goal was maybe a little more pep and a better filter in general.

If I'm following correctly the "readjusting" to factory parameters is done by the vehicle's computer and the gains will take time b/c the truck is figuring out the change i.e. K&N filter? My impression on purchasing the new filter was no tune would be needed nor was one recommended...did I miss something?

Added just K&N Filter

speeddemonxp97

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Hemi450hp

Moe's Performance

Kotta390

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Hootbro

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NJ'12HemiExpress

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