Budget K&N Air Intake Mod +'s, -'s, ?'s

[bonhommechristopher]

Hey all, I was recently given a K&N high flow pod filter in great condition. My boss at work was going to throw it in the trash, so I took it and fabricated a semi-cold/cooler air intake for my '03 2.4L Liberty. I have more power, definitely, but my gas mileage has gone down to 25 hwy, 21 city. I was getting about 25 mpg city before. I believe the filter was originally for a truck. Is there anything I can do to increase the efficiency of my vehicle? Do I need to mod the computer as well? I know what to do with carburetors, but I don't really know how fuel injected vehicles adjust. I'm thinking about a muffler delete too, would this help the flow if air and gasses through the engine or just make a lot of noise?

 

[tommudd]

Ditch that filter and intake system
The stock airbox does the best job of getting air into the engine
with a good paper filter

 

[Ocelot]

I've read that the only flow advantage you see with a k&n filter is at WOT..
I don't WOT too often.

 

[bonhommechristopher]

Like I said, the filter does seem to give me more power, but my gas mileage and who knows what else is suffering. I have only gone full throttle twice, that I can remember. I drive pretty easy most of the time. Thanks for the tips! I'll go back to the stock airbox and buy a new filter. Any tips to increase power with the stock airbox? The 4 cylinder is strong but sluggish. The K&N helped with that, but my mpg went way down.

 

[CalcityRenegade]

I second the OE airbox, I kept mine but replaced the filter with a K&N, I noticed a slight increase in performance, A bit better sound but I like it because it lasts much longer that a paper filter, I've used it for a year and its just starting to get a little dirty around the edges, A buddy gave me a new cleaning kit he bought but never used and I paid cost on the filter so it only cost me as much as 2 paper filters.

 

[tommudd]

Like I said, the filter does seem to give me more power, but my gas mileage and who knows what else is suffering. I have only gone full throttle twice, that I can remember. I drive pretty easy most of the time. Thanks for the tips! I'll go back to the stock airbox and buy a new filter. Any tips to increase power with the stock airbox? The 4 cylinder is strong but sluggish. The K&N helped with that, but my mpg went way down.

Not too much you can do with the 4, its just not quite enough for the weight of the KJ. Good tuneup etc and have fun with it

 

[dude1116]

Who knows...on the 2.4L replacing the stock airbox might have more benefits than replacing on the 3.7L. I feel like it hasn't been tested enough.

 

[tjkj2002]

Who knows...on the 2.4L replacing the stock airbox might have more benefits than replacing on the 3.7L. I feel like it hasn't been tested enough.

What you guy's don't realize is your engine in stock form(mechanically) can only suck in so much air and the OE airbox exceeds that by a fair amount and is the most CAI you can get.Also more airflow on any engine built after 1996 does not mean better mpg's,may have a slight power effect till the PCM relearns in a few trips.




If you really want a slight boost in mpg's for free,and don't live in a hilly area,plug your air filter.At about 80%-85% plugged you will notice a power drop but if driven normally you will see a boost in mpg's since OBDII will adjust,less air means less fuel which +'s better mpg's(but reduced power).

 

[dude1116]

Yeah I remember you saying that a smudged up filter will actually get you better mileage. Anyway I know nothing about the 2.4s or CRDs. Was just a thought. For all I know it's a different airbox.

 

[CactusJacked]

What you guy's don't realize is your engine in stock form(mechanically) can only suck in so much air and the OE airbox exceeds that by a fair amount and is the most CAI you can get.

Did the air box design change sometime after the 02 model? My stock air box isn't a "CAI", as it takes in it's air from within the engine compartment.

 

[profdlp]

What you guy's don't realize is your engine in stock form (mechanically) can only suck in so much...

Which is one thing that makes it different from your average politician. :mexsmoke:

 

[tommudd]

Did the air box design change sometime after the 02 model? My stock air box isn't a "CAI", as it takes in it's air from within the engine compartment.

All take air in from the intake mounted right under the lip of the hood on the core support, so is pulling in cooler air unlike the CAI sold which suck right close to the engine

 

[CactusJacked]

On other cars, I've dealt more with the true CAI that has the filter element outside the engine compartment. The other open filament shown is an HAI. Our setup is more like between the two.

 

[tjkj2002]

On other cars, I've dealt more with the true CAI that has the filter element outside the engine compartment. The other open filament shown is an HAI. Our setup is more like between the two.

There is always other factors to figure in.


Those "outside" the engine bay types are exposed to direct water ingestion,damage prone,and get dirtier faster.Those that suck hot air from under the hood,well no need to explain that one so yes the gas KJ's version is the better setup between the other 2 options.The CRD's got hosed on the bottom half of the airbox leading to major water ingestion and why the "02" air box mod is very popular with those guys.

 

[bonhommechristopher]

If you really want a slight boost in mpg's for free,and don't live in a hilly area,plug your air filter.At about 80%-85% plugged you will notice a power drop but if driven normally you will see a boost in mpg's since OBDII will adjust,less air means less fuel which +'s better mpg's(but reduced power).

What do you mean? There is an oxygen sensor on the throttle body, no? I didn't notice anything plugged up to my airbox. How do I unplug my filter? I've had some fun with the k&n experiment :whip:, it would be nice to get some higher mpg's now!

 

[tjkj2002]

What do you mean? There is an oxygen sensor on the throttle body, no? I didn't notice anything plugged up to my airbox. How do I unplug my filter? I've had some fun with the k&n experiment :whip:, it would be nice to get some higher mpg's now!

It's called a MAP sensor,Manifold Absolute Pressure sensor,and combined with what the PCM reads from the upstream O2's(given preset fuel maps) it knows how much air is entering the engine at any given time to adjust the injector pulse with.

 

[bonhommechristopher]

Ahhh okay. But wouldn't that make the engine run lean? I don't want to burn up my plugs or anything else for that matter just for the sake of 1-2 mpg. I'm back to stock now! going to pick up a new filter tomorrow. I'm running some Marvel Mystery oil in my gas and a splash in my oil too. I shone a light past my throttle and the inside looked nasty. hopefully the MMO will clean out my engine and injectors. The motor runs a little quieter, but it sounds happier now.

 

[tjkj2002]

Ahhh okay. But wouldn't that make the engine run lean? I don't want to burn up my plugs or anything else for that matter just for the sake of 1-2 mpg. I'm back to stock now! going to pick up a new filter tomorrow. I'm running some Marvel Mystery oil in my gas and a splash in my oil too. I shone a light past my throttle and the inside looked nasty. hopefully the MMO will clean out my engine and injectors. The motor runs a little quieter, but it sounds happier now.

No since the PCM adjusts the fuel to the air that the engine is able to suck in(it's just a big air compressor) to try and maintain 1.0 Lambda.

 

[bonhommechristopher]

plug your air filter.At about 80%-85% plugged...

Haha oops. I was reading this on my phone and saw "unplug". Needless to say, I was confused. Thanks for the explanation of the MAP sensor anyway! :Stupid Me:

 

[rcjohnson]

Tjkj would you recommend replacing the O2 sensors at any particular mileage? Would that help with mpg's?