Help ! My gas mileage ***** !

[hueyflyer]

Hi just installed a K&N 4.5 x 5" air filter hooked up through a Rustys Air Tube hoping to gain some gas milage improvement. Looks to have gone the wrong way. Went from an average of 19mpg to 18 mpg. The 18mpg was after approx 250 miles with about 70% of the driving under highway conditions at around 70mph. The rest around town. I did read under a different subject that the K&N took around 500 miles to show improvement. Does not make sence to me. Comments please!

 

[hueyflyer]

Oh I forgot to mention that my KJ has approx 18,300 miles on it.

 

[Tom D]

No, it doesn't really make any sense. THe K&N should improve both performance and fuel economy.

 

[SkidMarkSteve]

Mine gets between 14mpg and 16mpg. It's an 02 Limited. If it was a V-8 I could understand... :-s

 

[duelly]

should have bought the crd more power better to tow with and exceptional mileage both in the city and on the highway i love it . traded my 03 hemi 4x4 QC for this vehicle after approximately 8 months of research on the liberty both the 3.7 and the crd. the diesel was an easy choice 19mpg city and 24.5 highway at 70 mph only 670 kms on it so mileage will increase slightly after engine breaks in (libdarkk)

 

[kegjeep]

Hi just installed a K&N 4.5 x 5" air filter hooked up through a Rustys Air Tube hoping to gain some gas milage improvement. Looks to have gone the wrong way. Went from an average of 19mpg to 18 mpg. The 18mpg was after approx 250 miles with about 70% of the driving under highway conditions at around 70mph. The rest around town. I did read under a different subject that the K&N took around 500 miles to show improvement. Does not make sence to me. Comments please!

ive heard of a lot of people getting worse gas mileage when putting the K&N filter in. I just don't see how this would make that much of a difference in the first place, seems more like a sales pitch for the K&N than anything else.

Did you disconnect the battery for around 15 min to reset the computer when you put the K&N in? You would probably need to do that so it can adjust to the new fuel/air mixture ratios. Not sure, but its worth a try.

 

[-=JoN=-]

re=500 miles
you need to let the KJ adjust to the increased airflow...
i have the drop in, and i've gained 1-2 mpg after some time.

 

[tomjonesrocks]

Just installed a K&N 4.5 x 5" air filter hooked up through a Rusty's Air tube hoping to gain some gas mileage. Appears to have gone the wrong way! On the first fill up she went from an average of 19mpg to 18mpg. During this time I drove approx 3/4 highway miles at around 70mph for a total of 225 miles. I did read in a thread on a different subject that the K&N took 500 miles to start gaining mileage improvements. That really does not make sence to me. Comments please!

I've been debating between the K&N FIPK Kit and Rusty's--the Rusty's is obviously a much cheaper alternative.

Been skeptical about the gas mileage gain--the Rusty's would be worth it just for a flier for the cost of one fill-up but the FIPK system would take a couple years to pay off in savings even *if* you get a 1mpg-2mpg gain. I replaced the stock air filter with a K&N panel filter and got a big goose-egg for gain on that one. $45 down the drain, basically.

Really am interested to hear if anyone's getting a benefit from this. Looks like there was a "How To" done in March but I didn't read anyone sure they got a benefit. Not looking to do this just to make the engine louder.

Scott

 

[Tom D]

I've been using K&Ns for about 40 years and have always been very happy with them. The gain from a high-flow air filter like the K&N is mainly in performance and ultimate cost (from being reuseable). But any change in fuel economy with respect to a computer-controlled, fuel-injected motor will be negligeable. This is because the mass air flow or air density sensors, depending on which type of FI system you have, will regulate the injection to a constant fuel/air ratio regardless of the amount of air inducted. Thus, there is an increase in the amount of available horsepower, but that isn't going to come for free either. The amount of fuel necessary to produce any given amount of horsepower, with or without the K&N, stays the same.

I'm still searching for an answer as to why the Liberty's fuel economy is so crappy though. I've talked to a few guys at work who told me that it was common knowledge that Jeeps, in general, get lousy gas mileage. In fact, they acted surprised that I didn't already know that. So, if anyone can explain to me how it is that my Tahoe does better I'd sure like to hear it because I can't figure it out.

 

[mountainsurfer]

Just finished a long trip from Craig, Co to Mesquite, Nv. Criag to Green River Ut got 25 MPH. From GR to Mesquite it was 23. Had to turn on the AC. Coming back was 23 and 24.5. Only mods are Gibson exhaust and KN cold air pack.

 

[Okura_hubby]

I have a Rusty mod with large K&N cone filter. I will um sale/give to new home. Just would expect who ever to pay for shipping.. I am moving and doing some parts clearing. If interested let me know. Just want to cover my cost to send it to whoever.