You decide. Last week I towed the TT to Myrtle Beach. On the way down I kept wondering WHY my MPG was so low. Everything felt fine, no extra wind, but worse than usual MPG. I usually get 10, to the beach, and 9 1/2 home I barely got 9, actually high 8. Same thing on the way home. WHAT was the difference, what was wrong?Then yesterday it hit me. My K%N filter was dirty, And I didn't have time to clean it before we left, and besides, they don't help anyway, right. So I bought a Fram air filter, and stuck it in. Result. Loss of MPG. Could tell no difference in power.Well the K%N. Is being cleaned even as I type. It's goin back in. One MPG may not seem like much, but, it's alot when you ain't gettin none to start with. and in my truck, it's 27 miles

I did a lot of research on the K&N and came to one conclusion, NO WAY Jose. It filters LARGE particles only and allows the fine dust to enter the engine, which will kill an engine very quickly. If they were as great as they claim, why doesn't the vehicle manufacturer make them OEM, to boost the HP & torque..:?

Terryallan wrote:You decide. Last week I towed the TT to Myrtle Beach. On the way down I kept wondering WHY my MPG was so low. Everything felt fine, no extra wind, but worse than usual MPG. I usually get 10, to the beach, and 9 1/2 home I barely got 9, actually high 8. Same thing on the way home. WHAT was the difference, what was wrong?Then yesterday it hit me. My K%N filter was dirty, And I didn't have time to clean it before we left, and besides, they don't help anyway, right. So I bought a Fram air filter, and stuck it in. Result. Loss of MPG. Could tell no difference in power.Well the K%N. Is being cleaned even as I type. It's goin back in. One MPG may not seem like much, but, it's alot when you ain't gettin none to start with. and in my truck, it's 27 milesIf you think about it, what you are saying is impossible.Modern engines have MAF or MAP and O2 sensors in them. These sensors keep A/F mixtures EXACTLY at 14.7 and is updated hundreds of times a second.The more air you get into an engine the more fuel it will inject to keep it stoichiometric. The less air the less fuel it will inject.So even if your K&N filter gave your engine more air it also needed more fuel to go with it.You don't get better mileage by burning more fuel. A lot of things can cause poor mileage.You can make the argument you got more power, but not better fuel mileage.

I feel Frame is a poor choice for an air, fuel, or oil filter. Too many posts about them coming apart and causing damage. As for the K&N, My truck had one when I bought it but again I didn't feel comfortable with it as it is necessary that it be oiled properly and more often than I would like, so it sits on the shelf and a stock air filter is in. I use Wix and so far all is good. JMO.

Very Very carefully clean your MAF/MAS grid. It is possibly contaminated with oil from the K&N filter.

Out here in dusty west Texas the diesel mechanics do not recommend using a K&N. The heavy duty stock filters protect the engine better. They do require more frequent replacement if the dirt is blowing.

K&N air filters, help or not | Good Sam Community

35 Replies

Vulcaneer
Explorer
May 01, 2013
Tachdriver wrote:
Terry:

It would be interesting to see what your MPG is after re-installation, keep us updated.

I agree...follow the sequence...your mileage gradually got worse with the K&N. Then switched to Fram. It continued to get worse. Maybe the last 100 miles MPG with the K&N would be very similar to the first 100 miles MPG on the FRAM. It will be interesting to see if the clean K&N improves your MPG. I would expect not. I would bet it might be even a little worse, or similar to the FRAM filter. I don't think you are seeing a difference between two different filters. I think you are seeing a gradual decline in your MPG. Due to something else that is hurting you MPG.

And I would guess that by cleaning your MAF/MAS sensors that may help remedy the situation. But it could be something else too.

So once you clean the MAS/MAF, then test the MPG on both filters again.
Lynnmor
Explorer
May 01, 2013
Terryallan wrote:
Tachdriver wrote:
Terry:

It would be interesting to see what your MPG is after re-installation, keep us updated.

I will. Going back in July, same distance. Same terrain. Should be a APPLES TO APPLES RUN.

Traffic, weather, load, fuel, speed etc., there is NEVER apples to apples.
I agree with those folks that say use the stock filter and save your engine.
Terryallan
Explorer II
May 01, 2013
Tachdriver wrote:
Terry:

It would be interesting to see what your MPG is after re-installation, keep us updated.

I will. Going back in July, same distance. Same terrain. Should be a APPLES TO APPLES RUN.
Tachdriver
Explorer
May 01, 2013
Terry:

It would be interesting to see what your MPG is after re-installation, keep us updated.
Terryallan
Explorer II
May 01, 2013
I'm not arguing one way or the other. But I did see a 10% mpg drop, when it came out. So, It's going back in. Call it seat of the pants, call it impossible. But numbers don't lie.
Tachdriver
Explorer
May 01, 2013
Bonefish wrote:
Out here in dusty west Texas the diesel mechanics do not recommend using a K&N. The heavy duty stock filters protect the engine better. They do require more frequent replacement if the dirt is blowing.

Maybe they want to sell thier filters.

I have one in my BMW for the last 120,000 miles and never had a problem. If these filters are propoerly cleaned and oiled you should not have problems.

My MAF sensor is less than 12" from the filter and never had to clean the sensor.

The claimed improvement on acceleration and power is due to the better flow these filters provide. THey do not add horsepower but allow the throttle response to be better.

Across the board do they perform the same on all vehicles? Probably not but if you have better performance with this filter then by all means I would use it.

Again over time it would need to be properly cleaned and oiled, there is a technique to not over oil them as too much oil will adversely affect the performance.
webslave
Explorer
May 01, 2013
donn0128 wrote:
Very Very carefully clean your MAF/MAS grid. It is possibly contaminated with oil from the K&N filter.

All the above is true... The computer will negate all the "benefits" of a CAI or a CAT back unless you change the algorithms controlling air/fuel mixture, valve timing and engine timing. I used to use K&N systems (the last one was on my Hemi Jeep and I took it off after a few thousand miles; OBD II live data capture showed absolutely no change in performance, despite the "seat of the pants" impression) and you can, indeed, get into trouble with the oil type filters. In the old days (pre MAP/MAF/MAS sensors) it wasn't an issue, but, in today's engines, there is a very fine line that seperates just the right amount of oil and too little or too much...both of which can have serious reliability issues. The CAI / K&N systems do sound sweet though...
jmtandem
Explorer II
May 01, 2013
I ran a K and N filter on my 91.5 Dodge Ram Cummins and it actually ran better and was far less hassle using the stock filter than the K and N. I did not get any better seat of the pants power or fuel mileage with the K and N than stock and the K and N was a lot more effort to clean and re-oil than just dropping a new stock filter in every so often.
jim1632
Explorer
May 01, 2013
If you haven't done it recently, check the gap on your spark plugs. Just need to pull one to check. My truck has about 110k and I just changed the plugs. Gap was .050 instead of the specified .040 on all my plugs due to wear.
rottidawg
Explorer
May 01, 2013
Close to $300 for the CAI system and many, many bad reviews and problems.....i think I would pass.

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K&N air filters, help or not

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