Oil from the filter media can mist sensitive post-filter sensors (modern vehicles) (e.g. the MAF or whatever if anything is there on a particular vehicle). Surely this damage will not be covered under warranty.

It is also possible (I have not researched it) that modifying the intake to accept a non-standard filter might void some warranties as well, being viewed as a modification of the manu's product. This is a much-discussed topic on performance-car boards.

 

Three things to note/comment on.

First, Ed_T is right about summer gas improving mileage. I don't know when summer gas is used around here, so it is possible that is the effect I saw.

Second, wwest, I almost never use WOT. If I did, do you really think I could have a nearly 500 mile tank with 37 mpg?

Third, Ed_T, I did not modify anything on my vehicle for this. I simply replaced the paper filter with the K&N filter. That's it. As to the misting of the MAF sensor, this is certainly one that is discussed a lot. As far as I could tell, no manufacturer has actually come out against K&N. A few have tried, but backed off eventually. If you have specific cases where a manufacturer has blamed K&N for destroying sensors, I would really like to read them, so please send links my way.

Since I have a nice and new paper filter sitting in my garage, I might just switch it back and drive another 2000 miles to see if the results repeat.

 

WOT does NOT mean you have your foot to the floor. You do not have a mechanical linkage to your throttle, everything is computer controlled, and your gas pedal is simply a computer joystick, or type of potentiometer.

This car goes WOT much more than you realize. I'd bet each and every one of you go WOT taking off from nearly every dead stop. ( not in EV of course ) This is counter-intuitive, but actually productive for good MPG.
WOT is the MOST EFFICIENT PLACE to run your car. WOT is the place you get the most power per drop of gas. With the eCVT and planetary power split, you ( er... the computer ) can run the engine throttle "wide open" at any time

One thing I monitor is MAP ( Manifold Absolute Pressure ). In my FEH, whenever my MAP pressure = the pressure of out-side atmosphere, I assume I'm at WOT. It is very hard to avoid WOT in this car, actually. It will go WOT taking off from a light at the pace of a bus, or on the slightest grade. It will go WOT when you think you are being "gentle" but the ICE needs to "work" to spin the generator and charge the battery. Remember, you can be at WOT and if all that power is not needed at the wheels, all the "left over" torque can be used to spin a generator. This car does not behave like any other car you have driven.

How soon you reach WOT is also related to altitude.
Approximate values for Wide Open Throttle:

MAP of 14.5 psi at Sea Level = WOT
MAP of 14.0 psi at 1000' = WOT
MAP of 13.5 psi at 2000' = WOT
MAP of 13.0 psi at 3000' = WOT
MAP of 12.5 psi at 4000' = WOT
MAP of 12.0 psi at 5000' = WOT
MAP of 9.5 psi at 10,000' = WOT

MAP at engine idle, is about 3.0 psi.

The difference between your current MAP and WOT MAP is how much vacuum you have. Vacuum is a drag on the engine, and NOT good for fuel efficiency. At WOT you are at ambient, and have no vacuum pressure. Idle at 5000' = 9 psi of vacuum.

Real world example. My driveway is about 8% upslope. When I go up this hill at 5 MPH, and 1300 RPM, my MAP is 12.2 psi at 4700' elevation. I interpret this as the engine running wide open throttle, even though I have a very light touch on the gas pedal, and am moving very slow. The computer calculated this was the best, most efficient way to get the power I needed to climb this hill, at this speed.

Long ( hopefully informative ) story. Short Point. Air intake is more important than you may realize, and you are running WOT more than you realize.
-John

 

I have been using K&N filters for years on my hot-rod Harleys & I like them a lot. They perform very well & that is why we use them on the race bikes.

There is no way I believe that dropping in a K&N increased a Hybrids mpg by two however, there had to be other factors at work here.

K&N filters certainly do not filter as well as a good paper pleated filter either (as someone else stated). Heck, you can see right through the filter media if you are in a well lit area.

I don't really worry about it, I have had bike motors run over 100,000 miles running exclusively K&N. I can't really see a reason to put one in my Hybrid however. You could DEFINITELY have MAF sensor problems by over-oiling & I don't need that.

~John

 

You could easily be right, it could have been other factors. I did try to minimize those, but could easily have missed something, or possibly something out of my control happened.

Of the things mentioned here, the only one I can see is a change from winter to summer gas. I don't know when that happened around here. And I am open to any more ideas.

Perhaps I will try the reverse test, switching back to a paper filter. Until then, the numbers are accurate for what they are.

 

Does anyone know if K&N makes a replacement filter for the 08 yet? A guy at the Ford dealership I purchased my FEH from said the 07 one should work?

 

Is this unique to the Ford hybrid system or CVTs?

My scangauge Throttle Position Sensor TPS reading never shows 100, it's usually in the 18-28 range. I don't get a MAP reading with my vehicle.

 

Throttle position sensor, in this case, I think, should be called "gas pedal position" sensor.

I can get wide open throttle with the gas pedal hardly being pressed, since it is all computerized "drive by wire". I don't think I've ever seen my throttle position ( in this case, pedal position ) past about 60. But I have to admit, I don't watch that one very often, since I did not find it very helpful.

 

I haven't watched the TPS before either, but after reading your post I checked it out this morning as I was curious. It can't be called the gas pedal position either since with cruise control my pedal doesn't even move in and out like the old cable system would. Since I'm curious I'll waste a little gas and see what the max reading is tomorrow.

The scangauge description says "in some vehicles, a closed throttle will read 0 and full throttle will read 100. Other vehicles will have a higher value than 0 for a closed throttle an open throttle value less than 100"

Could be anywhere it seems.

 

TPS might more correctly mean "engine torque production COMMAND". Gas pedal or cruise control could be the source of the command signal.