Mustang GT and K&N air charger

"C. E. White" > wrote in message
...
>
> "Michael Johnson" > wrote in message
> ...
>
>> What we are talking about is if a dirty filter affects gas mileage. It
>> does. The degree to which it affects it depends on how much dirt is in
>> the filter. A more efficient engine requires the throttle to be open
>> less to make the same amount of power. If the throttle is opened less
>> then less gas is used and the doesn't have to be under a greater load to
>> perform its tasks.
>
> Clearly you don't understand how modern fuel injection systems engines
> work. One last time - The output of the engine is dependent on how much
> air can be pulled into the cylinders. The amount of air drawn into the
> engine is controlled by the total intake tract restriction (filter,
> piping, throttle plate, valves opening, etc.). As long as you are not at
> wide open throttle, to achieve a particular power output, an increase in
> the restriction of one part of the system is compensated for by a change
> in the throttle position. The total restriction is the same for a given
> power output at a given rpm. The only sensor that is even slightly
> affected by minor changes in air filter flow restriction is the throttle
> position sensor. As I have pointed out repeatedly, this is just a gross
> position indicator. It is incapable of providing the sort of precise data
> that would indicate the minor change in the throttle position necessary to
> compensate for a slight difference in the flow resistance related to the
> air filter. The rest of the sensors used to control the amount of fuel
> injected will not be affected by reasonable differences in air filter
> restrictions (I am not talking about a completely plugged filter).

BULL**** ED!
Clearly you don't understand how modern fuel injection systems engines work.

Dyno testing the 2005 GT has shown that the computer is so sensitive to
airflow changes that a computer modification is necessary in order to
control the air/fuel ratio at the proper level. Installing this air intake
assembly on a 2005 GT without any tuning will result in a leaner-than-ideal
14:1 air/fuel ratio. While certainly not lean enough to cause engine
durablility concerns, it is leaner than what is desired for optimum
performance. Even when replacing the air filter ONLY to a higher flow
assembly, the air/fuel ratio leans out at an alarming rate.
http://www.allfordmustangs.com/revie...hp/product/394




>
>> Depending on the application, a K&N filter and/or intake system MAY
>> improve mileage by making the engine more efficient.
>
> How does it make the engine more efficient????????????????????????????? It
> may allow the engine to pull in more air when the throttle is at wide open
> throttle, but this does not mean the engine is more efficient. It just
> means the engine can develop more power. And, if you take advantage of
> this extra power, you may actually reduce your fuel economy.....
>
>> It depends on how efficient the stock intake system is it replaces. I
>> would be willing to bet a K&N would flow better than a stock paper filter
>> if each one had 30k miles on them and that toward the end of an OEM
>> filters life the difference in gas mileage between them would be in the
>> K&N's favor.
>
> I am willing to wager there would be no detectable difference. Unless you
> are at wide open throttle, the amount of air needed to maintain a give
> power output (or speed under a give set of conditions) is going to be the
> same. If the K&N filter is less restrictive than the paper filter, it just
> means the throttle plate will be slightly less open. The total intake
> tract resistance will be the same.
>
>> In your statement above you admit a dirty filter has an impact on
>> mileage.
>
> Which statement was that? Do you mean when I said - "But if we are just
> talking about filters operating in the normal range of contamination one
> would expect to see for a properly maintained engine, then the air filter
> is a not going to have a significant effect on fuel economy. And I stand
> by my statement that there is no reason to expect a K&N air filter to
> provide a significant (= measurable) improvement in the fuel economy of a
> modern fuel injected engine [compared to a reasonably well maintained
> paper filter]."
>
>> I never said the impact was significant across a filters recommended
>> life but only that it did occur to some degree. Maybe the degree is less
>> than what one would see on an engine with a carburetor but it is still
>> there.
>
> Significant = measurable (in my mind). A dirty air filter on a carbureted
> engine will have a measurable impact on fuel economy. However, even for a
> carbureted engine it has to be really dirty. I never let one get dirty
> enough to cause a problem, but I understand the sound reasons why a dirty
> filter could affect a carbureted engine's fuel economy. For modern fuel
> injected engines, there is no sound engineering reason to think that at
> air filter that is changed at reasonable intervals will affect fuel
> economy. The nature of the modern fuel injection systems eliminates the
> reasons why filter contamination affects fuel economy. The difference in
> air flow between a K&N and a paper filter is trivial in most cases. It is
> certainly a non-factor in regards to fuel economy.
>
> Ed
>
>

"Bob Willard" > wrote in message
...
> Michael Johnson wrote:
>
>> Ed White wrote:
>>
>>> "Michael Johnson" > wrote in message
>>> ...
>>>
>>>> Ed White wrote:
>>>>
>>>>> "Michael Johnson" > wrote in message
>>>>> ...
>>>>>
>>>>>> I think we will have to agree to disagree.
>>>>>>
>>>>>> Ed White wrote:
>>>>>>
>>>>>>> <snip>
>>>>>
>>>>> I was really looking forward to you picking out the mileages were the
>>>>> air filter was changed...
>>>>
>>>> I never said the variation in mileage was great over the recommended
>>>> life span of the filter. Only that there is variation. There are many
>>>> other things that can effect mileage more so your numbers don't show
>>>> anything unless you let the filter get very dirty. Even the time of
>>>> year you buy gas affects mileage more than many things can. I can go
>>>> through an refute every point you made but I've already done it so what
>>>> is the use of doing it again? We have beat the horse, it is dead and
>>>> now it is starting to look like hamburger.
>>>
>>>
>>> I guess you are right, it is just a shame to see someone who can't grasp
>>> basic facts. All of your arguments seemed to depend on large variations
>>> in air filter restriction. A K&N provides a trivial improvement,
>>> certainly down in the noise range as far as the PCM of a modern fuel
>>> injected engine is concerned. Even K&N admits that a dirty K&N won't
>>> flow as well as a clean paper filter (see
>>> http://www.fuelinjection.net/kne/kne_test.htm ). You can't seem to grasp
>>> the idea that for any sort of reasonable air filter restriction, the
>>> source of the total intake restriction (filter, plumbing, throttle,
>>> valves) is all that matters. If the air filter is a little more
>>> restrictive, then the throttle is just a little more open and the total
>>> air flow is the same. You seem to hang your whole argument on the
>>> throttle position sensor. I completely refuted this claim by providing
>>> you with the reference values for a Mustang TPS. No other sensor will
>>> even be slightly affected.
>>
>>
>> Here is a cold hard fact..... gas mileage deceases as an air filter
>> becomes more restricted. If you plotted mileage verses the degree of
>> filter restriction the resulting line would not be linear. Under light
>> clogging there is little impact but as the filter efficiency decreases
>> substantially so does mileage. You are confining you argument to the
>> small zone where the air filter is still operating with a high
>> efficiency. Even there, a trivial reduction in mileage is still a
>> reduction. As the filter gets progressively dirtier the effect it has on
>> mileage is further magnified.
>
> Maybe so, but repeating the same claim over and over does not impress me
> as much as seeing results of testing on a modern FIE engine would. Do you
> have a URL for such a test report? The URL you gave earlier did not
> contain any test data; only dogmatic statements.
> --
> Cheers, Bob


http://www.allfordmustangs.com/revie...hp/product/394

"Ed White" > wrote in message
...
> ****lots of previous stuff removed*****
>
> I'll take one last stab at this.....
>
> The basis of your argument seems to be that automotive engineers are
> idiots who cannot design a fuel injection system that will compensate for
> a minor difference in the flow restriction of an air filter. I don't
> believe this to be the case.

Correct, refer to following link:

Dyno testing the 2005 GT has shown that the computer is so sensitive to
airflow changes that a computer modification is necessary in order to
control the air/fuel ratio at the proper level. Installing this air intake
assembly on a 2005 GT without any tuning will result in a leaner-than-ideal
14:1 air/fuel ratio. While certainly not lean enough to cause engine
durablility concerns, it is leaner than what is desired for optimum
performance. Even when replacing the air filter ONLY to a higher flow
assembly, the air/fuel ratio leans out at an alarming rate.
http://www.allfordmustangs.com/revie...hp/product/394




>
> I dug out the Ford shop manual for a 1999 Mustang 2V 4.6 Liter engine. The
> PCD includes TPS reference voltage values for a 1999 Mustang 4.6L V-8 - At
> idle the voltage is OK if it is anywhere between 0.52 and 1.27 V. At 30
> mph, the acceptable range is 1 to 1.2 V. At 55 mph the acceptable range is
> 1.2 to 1.5 V. Clearly the tps value is not a major determining factor in
> adjusting the A/F ratio since the acceptable values at idle and 55 mph
> actually overlap. No other sensor related to the A/F ratio are affected by
> the air filter restriction. The only other sensors in front of the
> throttle plate are the MAF sensor and air temperature sensor. Neither
> will be affected by small changes in pressure in the intake tract related
> to the air filter restriction. A 1999 Ford 4.6L does not utilize a
> barometric pressure sensor.
>
> The following sensor are part of the system:
>
> Camshaft Position (CMP) Sensor -4.6L
> Crankshaft Position (CKP) Sensor -4.6L
> Throttle Position (TP) Sensor
> Idle Air Control (IAC) Valve -4.6L, (2V)
> Engine Coolant Temperature (ECT) Sensor -4.6L, (2V)
> Mass Air Flow (MAF) Sensor -4.6L, (2V, 4V)
> Intake Air Temperature (IAT) Sensor
> Heated Oxygen Sensor (HO2S)
> Catalyst Monitor Sensor
> Clutch Pedal Position (CPP) Switch
> Fuel Pressure Sensor
>
> Except for the TPS, none of these will be affected by normal sorts of
> changes in the air filter restriction. As I have tried to explain
> previously, the TPS is just a gross indicator of the throttle position. It
> is not designed to be used for the sort of fine A/F ratios you are
> suggesting it is used for. The range of acceptable output valves for a
> given throttle position is so wide that it cannot possibly be a
> determining factor when evaluating changes in fuel economy as a result of
> changes in air filter restriction.
>
> The following is from the PCD manual for a 1999 Mustang:
>
> -----
>
> "Fuel Trim
>
> The fuel control system uses the fuel trim table to compensate for normal
> variability of the fuel system components caused by wear or aging. During
> closed loop vehicle operation, if the fuel system appears "biased" lean or
> rich, the fuel trim table will shift the fuel delivery calculations to
> remove the bias. The fuel system monitor has two means of adapting Short
> Term Fuel Trim (FT) and Long Term Fuel Trim (FT). Short Term FT is
> referred to as LAMBSE and Long Term FT references the fuel trim table.
>
> Short Term Fuel Trim (Short Term FT) (displayed as SHRTFT1 and SHRTFT2 on
> the NGS tool) is a parameter that indicates short-term fuel adjustments.
> Short Term FT is commonly referred to as LAMBSE. LAMBSE is calculated by
> the PCM from HO2S inputs and helps maintain a 14.7:1 air/fuel ratio during
> closed loop operation. This range is displayed in percentage (%). A
> negative percentage means that the HO2S is indicating RICH and the PCM is
> attempting to lean the mixture. Ideally, Short Term FT may remain near 0%
> but can adjust between -25% to +35%.
>
> Long Term Fuel Trim (Long Term FT) (displayed as LONGFT1 and LONGFT2 on
> the NGS tool) is the other parameter that indicates long-term fuel
> adjustments. Long Term FT is also referred to as Fuel Trim. Long Term FT
> is calculated by the PCM using information from the Short Term FT to
> maintain a 14.7:1 air/fuel ratio during closed loop operation. The Fuel
> Trim strategy is expressed in percentages. The range of authority for Long
> Term FT is from -35% to +35%. The ideal value is near 0% but variations of
> ±20% are acceptable. Information gathered at different speed load points
> are stored in fuel trim cells in the fuel trim tables, which can be used
> in the fuel calculation.
>
> Short Term FT and Long Term FT work together. If the HO2S indicates the
> engine is running rich, the PCM will correct the rich condition by moving
> Short Term FT in the negative range (less fuel to correct for a rich
> combustion). If after a certain amount of time Short Term FT is still
> compensating for a rich condition, the PCM "learns" this and moves Long
> Term FT into the negative range to compensate and allows Short Term FT to
> return to a value near 0%.
>
> As the fuel control and air metering components age and vary from nominal
> values, the fuel trim learns corrections while in closed loop fuel
> control. The corrections are stored in a table that is a function of
> engine speed and load. The tables reside in Keep Alive Random Access
> Memory (RAM) and are used to correct fuel delivery during open and closed
> loop. As changing conditions continue the individual cells are allowed to
> update for that speed load point. If, during the adaptive process, both
> Short Term FT and Long Term FT reach their high or low limit and can no
> longer compensate, the MIL is illuminated and a DTC is stored."
>
> -----
>
> And finally, here is a challenge for you. The chart below lists the
> average fuel economy over 900 to 1250 mile intervals for my 2006 Nissan
> Frontier - tell me approximately at which points the air filter was
> changed......should be a piece of cake if filter restriction affect fuel
> economy as drastically as you think. This truck is a farm vehicle and
> spends a significant amount of time on dirt road and field paths. It
> probably saw more dust last October than your Mustang has ever seen (I
> pick peanuts in October - almost nothing generates more dust).
>
> Cum. Avg
> Miles MPG
> Since previous period
> ------- ---------------------
> 1176 18.1
> 2132 18.9
> 3274 19.0
> 4234 17.9
> 5276 18.2
> 6433 17.2
> 7358 18.7
> 8488 18.9
> 9540 18.8
> 10666 18.1
> 11812 19.2
> 12888 19.3
> 13995 19.2
> 15230 18.6
> 16276 19.1
> 17425 19.0
> 18518 17.9
> 19454 18.6
> 20444 19.0
> 21375 18.1
> 22423 18.1
> 23543 18.4
> 24684 18.2
> 25684 18.8
> 26895 18.9
> 27889 19.3
> 29045 17.7
> 30199 19.3
> 31203 18.8
> 32151 20.1
> 33175 19.6
> 34236 19.7
> 35313 20.5
> 36396 18.9
> 37403 19.3
> 38325 19.6
> 39306 19.9
> 40275 19.5
> 41311 19.8
> 42494 18.6
> 43721 19.2
> 44685 18.2
> 45757 18.8
> 46686 18.8
> 47745 18.7
> 48456 19.3
>
> Ed
>

"C. E. White" > wrote in message
...
>
> "Michael Johnson" > wrote in message
> ...
>
>> Does an engine under a heavy load run richer than one that is under a
>> light load? The ECU has load tables that it uses to help calculate what
>> it believes the optimum air fuel ratio should be taking into account the
>> conditions it thinks the engine is operating under. What the computer
>> thinks is optimum isn't always 14.7:1. The computer expects the
>> operator to keep the filters fresh and a dirty air filter makes the ECU
>> think the engine is under a heavier load and thus changes the target A/R
>> to run richer than normal. This in turn reduces gas mileage.
>
> Some of what you say is true, but your conclusion are wrong. As I said
> before, the throttle position sensor is the only sensor that will even
> show a minor variation as a result of a change in air filter restriction.
> And throttle position sensors are not precise at all. They are gross
> indicators, used primarily to communicate rapid changes in the throttle
> position (i.e., mashing down or letting up) so the PCM will be able to
> temporarily enrich the mixture (mimicking the accelerator pump of a
> carbureted engine) or change the IAC setting to prevent the engine from
> stalling as the speed falls back to idle (like a dashpot).
>
>> ECUs
>> aren't clairvoyant and can determine the degree to which an air filter
>> is dirty. It only takes the input from ALL the sensors and using
>> preprogrammed tables makes A/F adjustments (and many other) to the
>> conditions it perceives the engine to be operating under. Determining
>> engine load is a very important component is what it uses to set the
>> target A/F at any given moment. This is why they put throttle position
>> sensors on engines nowadays. The new Mustangs are somewhat different in
>> that there is no longer a direct wire connection to the throttle plate.
>> The computer senses the position of the accelerator pedal and then
>> sets the throttle opening accordingly.
>
> Not just Mustangs are fly by wire. But again, you are missing the key
> truth. An air filter, even a used one, is a minor restriction comapred to
> other elements in the intake system. When crusing at a steady speed (say
> 60 mph), the air drop across the engine air filter is going to be less
> than 0.3 psi. The pressure drop across the throttle plate will be on the
> order of 7 psi. The difference in pressure drop between a clean K&N filter
> and a reasonably dirty paper filter is probably less than 0.1 psi. Is it
> your claim that this small change is going to upset the PCM so much that
> it can't maintain the proper fuel to air ratio? There will be a bigger
> difference in the pressure after the air filter if you drive the car from
> sea level to the top of a 5000 ft mountain that any change in pressure
> related to normal changes in the filter restriction. If you truly believe
> this, why doesn't installing a K&N upset the PCM parameters?


It does.

Dyno testing the 2005 GT has shown that the computer is so sensitive to
airflow changes that a computer modification is necessary in order to
control the air/fuel ratio at the proper level. Installing this air intake
assembly on a 2005 GT without any tuning will result in a leaner-than-ideal
14:1 air/fuel ratio. While certainly not lean enough to cause engine
durablility concerns, it is leaner than what is desired for optimum
performance. Even when replacing the air filter ONLY to a higher flow
assembly, the air/fuel ratio leans out at an alarming rate.
http://www.allfordmustangs.com/revie...hp/product/394




>
>> I have a TwEECer chip in my '89 LX that lets me program almost all of
>> the EEC-IV operating parameters. I know load tables exist and they
>> affect A/F as do many other sensor readings. There is a lot more going
>> on in the ECU than reading air in and making a simple computation for
>> fuel required. Things like engine acceleration rate, load, etc. come
>> into play in a big way. When something like a dirty air filter causes
>> readings of the throttle position sensor to be out of the range it
>> expects for a given driving condition then gas mileage can, and will, be
>> affected. The computer doesn't know the air filter is dirty and tries
>> to run the engine in a manner that isn't optimum for gas mileage. It
>> thinks you are doing something like climbing a hill, or accelerating,
>> and delivers fuel accordingly.
>
> Again, the throttle position sensor is just a gross indicator. The change
> in the position of the throttle related to normal variations in air filter
> restrictions will be trivial at cruise speeds. As the throttle angle
> changes from 4 degrees to 90 degrees, the tps ratio of output voltage to
> input voltage will go from around 0.2 to 0.98. The accuracy of the output
> is on the order of +/- 20%. There is no way a reasonable change in the
> restriction of the air filter is going to cause a greater change in the
> output of the TPS than normal variations inherent in the design of the
> tps. Automotive throttle position sensors are not highly accurate. And the
> PCM is able to use the feedback from the O2 sensor to compensate.
>
>> The A/F doesn't remain constant across the entire load range an engine
>> can experience. As the load increases the target A/F decreases. This
>> is programmed into the load data tables of ECUs. If the A/F didn't
>> decrease then cylinder temperatures would get too high and start melting
>> things like piston tops.
>>
>> To further make my point does an engine get better gas mileage going
>> downhill or uphill at the same speed? Is that because in one condition
>> the engine is under a heavier load than the other? If the rpm rate is
>> the same for each condition then why is the mileage different? It is
>> because the throttle has to be open more going uphill to get the air
>> necessary to make the power needed to overcome the elevation increase.
>
> Ths had nothing to do with wether or not the air filter restriction has
> any affect on fuel economy.
>
>> The data tables for engine load the computer uses are very specific to
>> the size of the throttle body put on the car. It relies on these tables
>> in conjunction with throttle position readings to determine what target
>> A/F is used from the load table. It also uses the O2 readings to fine
>> tune the A/F but only to meet the target A/F from the load table. A
>> dirty filter requires an increase in throttle opening which triggers the
>> computer to operate from the higher end of the load tables. Hence the
>> engine runs richer and gets lower mileage.
>
> The change in the throttle opening related to normal changes in air filter
> restriction is trivial. You are talking about gross changes that are far
> from normal.
>
>>>> I'm not saying a K&N filter will give a noticeable improvement in gas
>>>> mileage over an OEM unit but with all things being equal the engine
>>>> with a more efficient filter will perform better. Do you think an
>>>> engine with a dirty air filter would pass an emissions test? If so
>>>> then why not?
>>>
>>> As long as the filter is in good shape, it will have no significant
>>> effect on the ability to pass an emissions test. See above for the
>>
>> So if the filter is dirty enough then it will affect whether the
>> emissions test is passed? This means the A/F ratio isn't optimum,
>> doesn't it? If what you are saying is true then the computer should
>> compensate and make the A/F optimum thus allowing it to pass the test.
>
> Exactly. I can certainly imagine cases where a filter that is severely
> contaminated could cause a modern fuel injected vehicle to fail an
> emissions test, but this would be an exceptional case. For any reasonably
> well maintained vehicle, with an air filter changed per the manufacturers
> recommendations, you aren't going to fail an emissions test because of the
> air filter. If you want to hypothesize a very restrictive filter, all bets
> are off.
>
>>> reasons. I won't argue that a K&N might provide a slight performance
>>> increase at WOT. It very well might. But for anything but large throttle
>>> openings, the throttle plate is by far the most significant restriction
>>> in the intake tract. The filter is almost not there as far as air flow
>>> is concerned until the throttle is nearly wide open. Again, I am only
>>> talking about modern fuel injected engines. For older carbureted
>>> engines, a restrictive air filter would definitely significantly reduce
>>> fuel economy. And the situation is not clear to me if you are talking
>>> about some of the early speed density type fuel injection systems
>>> (systems without a MAF). For normal sorts of air filter restriction the
>>> PCM of these types of systems would be able to compensate for a
>>> restrictive air filter. However, for a very restrictive filter, they may
>>> not. However, as far as I know, no one has sold a car with a speed
>>> density only system for a decade.
>>
>> You keep saying for "normal sorts of air filter restrictions" when a
>> restriction is a restriction. A filter just doesn't not affect mileage
>> one day and then suddenly becomes dirty enough to affect it the next.
>> It is a gradual progression that happens continuously and in most
>> circumstances is too slow for the driver to perceive.
>
> By normal, I mean real world situations. Again, if you want to theorize
> about some wacky almost plugged filter, then all bets are off. Once
> again - unless you are operating near wide open throttle, any restiriction
> in the intake related to the air filter is trival compared to the
> restriction of the throttle plate.
>
>> Also, the basic operating parameters of an engine doesn't change because
>> it is fuel injected and computer controlled. The computer actually
>> mimics the old carburetors, governors, points etc. by using sensor
>> readings. The ECU controlling today's engines isn't a HAL 9000 that
>> thinks like a human. If it is getting garbage input from the sensors
>> then it spits garbage out to control the engine. The effect of a dirty
>> air filter on a fuel injected engine is the same as one with a
>> carburetor. On both engines the dirty filter puts the engine under load
>> and it is this that decreases gas mileage in both cases.
>
> THINK!!!!!!!!!!!!!!!!!!!!!! Why does a dirty filter impose any more load
> on an engine than a partially closed throttle plate. Do you understand
> carburetors? Do you know why they have a choke plate in front of the
> metering jets. Do you understand how the choke enriches the mixture. Can
> you see why for a carbureted engine a dirty filter might act like a choke
> and affect the mixture. Don't you understand that none of this applies to
> modern fuel injected engines? Carburetors depend on the Bernoulli
> principal to meter fuel. The fuel in the bowl is under atmospheric
> pressure. The pressure in the venturies is related to the flow through the
> venturies. If you place a restriction in front of the venturies, you will
> pull an artificially high vacuum in the venturies (higher than created by
> the Bernoulli principal), drawing more fuel into the air stream. Anything
> (like a choke, or a plugged air filter) affects the balance between the
> pressure on the fuel in the fuel bowl and the pressure in the venturies
> will affect the fuel to air ratio. This is why a clogged air filter can
> greatly affect the fuel economy of a carbureted engine. A fuel injected
> engine determines the amount of fuel my measuring a lot of parameters.
> None of these parameters is going to be significantly affected by normal
> variations in the filter restriction.
>
>>> By the way, the DIY Basics sight you referenced is loony
>>> (http://tinyurl.com/2hyeyx). You should follow your vehicle
>>> manufacturers replacement schedule for the air filter. I think that
>>> sight must be run by filter manufacturers.
>>>
>>> You should read these sites:
>>>
>>> http://www.visteon.com/utils/whitepa...05_01_1139.pdf
>>
>> I searched the PDF for "gas mileage" "mileage" and "mpg" and got no
>> hits. It's a little too long for me to read through but it seems to
>> address filtering efficiency for removing particulates and not the
>> effect of dirty air filters on gas mileage.
>>
>>> http://www.filtercouncil.org/techdata/tsbs/89-3R3.html
>>
>> This also seems to be addressing filter efficiency for removing
>> particulates and not gas mileage efficiency.
>
> True. I just thought you might find it interesting. They were meant to
> refute the idea that it was a good idea to change filters based on the
> advise at the DIY Basics site you referenced. I thought it was bad advice.
>
>>> Air filters (paper and K&N) are less efficient at removing dirt when
>>> they are new. As the accumulate particles, the filtering efficiency
>>> improves. So changing your filter too frequently (or cleaning your K&N
>>> too often) can actually increase engine wear. You should also consider
>>> that K&N filters loads up with dirt much faster than paper filters (they
>>> have less dirt holding capacity). So while they may enjoy a flow
>>> advantage when new (or when just cleaned), the advantage decreases
>>> rapidly with time.
>>
>> I have no doubt that a K&N filter lets more particulates by (and
>> therefore more air itself) than an OEM filter. Where the debate starts
>> is whether is has any appreciable impact on engine longevity for the
>> average vehicle. I believe it doesn't based on my own experience. My
>> '89 LX had had the same filter installed for over 130k miles and I had
>> the heads off at around 150k miles and saw no appreciable cylinder wall
>> wear. It also doesn't noticeably use any more oil than when it was new.
>>
>> The air filter debate is similar to the synthetic verses conventional
>> oil debate. IMO, there is no appreciable difference in wear from using
>> any oil that is changed every 3,000-4,000 miles. The contaminants never
>> get a chance to build up in the oil to cause a problem whether the oil is
>> synthetic or conventional.
>
> This time I am not trying to debate how well a K&N filter "filters." I am
> only arguing that there is no reason to expect a K&N filter to increase
> the fuel economy of a modern fuel injected engine (compared to a paper
> filter in reasonable condition).
>
> Ed
>

"My Name Is Nobody" > wrote in message
news:drvlj.8919$4b6.4815@trndny08...

> BULL**** ED!
> Clearly you don't understand how modern fuel injection systems engines
> work.

Well I believe I have a very good understanding of how they work.

> Dyno testing the 2005 GT has shown that the computer is so sensitive to
> airflow changes that a computer modification is necessary in order to
> control the air/fuel ratio at the proper level. Installing this air intake
> assembly on a 2005 GT without any tuning will result in a
> leaner-than-ideal 14:1 air/fuel ratio. While certainly not lean enough to
> cause engine durablility concerns, it is leaner than what is desired for
> optimum performance. Even when replacing the air filter ONLY to a higher
> flow assembly, the air/fuel ratio leans out at an alarming rate.
> http://www.allfordmustangs.com/revie...hp/product/394

You (and your reference) are talking about changes that are outside of the
bounds of what I am claiming. I am not arguing about the effect of K&N
filters on maximum power. And I am not even arguing about what happens at
wide open throttle on a dyno. My contention is simple - a K&N air filter
should have no significant effect on the fuel economy of an otherwise
unmodified engine, being driven in a normal manner, if you are comparing it
to a properly maintained paper filter. The difference in flow restriction
between the two is trivial under normal operation (not wide open throttle).
Why do you think a K&N would provide better fuel economy? The only sensor
that can even be marginally affected is the TPS and as I have repeated over
and over, a TPS is not a highly precise sensor. The trivial difference in
throttle opening at a steady cruise related to installing a K&N in place of
a normal paper filter is to small to show up as anything more than noise to
the PCM. There is plenty of adjustability built in to the PCM that will
allow it to compensate for this sort of trivial change. And when it can no
longer compensate, it will turn on the check engine light.

I am definitely not making any claims with regards to system that are
heavily modified (different MAF, new exhaust and ESPECIALLY not changes to
the PCM programming).

As for your reference - it is clearly a sales piece. The claim that the "the
2005 GT has shown that the computer is so sensitive to airflow changes that
a computer modification is necessary in order to control the air/fuel ratio
at the proper level" has no bearing on my argument. The modifications
referenced in the article included a non-Ford, large diameter, MAF This is
clearly far beyond simple modifications to the air intake in front of the
MAF. The PCM is designed to work with a MAF sensor that is designed to work
in a certain diameter housing. Even if you used the same physical MAF
sensor, placing it in a different diameter air passage changes how it
responds to changes in air flow. For instance using the same MAF element in
a larger bore housing would underestimate the air flow, resulting in a lean
condition unless new parameters are loaded to the PCM. Clearly a
modification of the PCM parameters is required by the large bore MAF used by
this company. I assume you did notice that the company also sells a street
setup that does not require PCM modification (yet they claim it still
provides significant power increases). One further critique of people
running these sort of tests - the PCM does not instantly compensate for
radical changes. The fuel trim is adjusted over a reasonable period of time.
While running in feed back mode, a sudden change is compensated for quickly.
However, it takes longer to modify the fuel trim parameters. These
parameters affect how the PCM responds to non-feedback situations (transient
conditions, WOT, cold engine). After making a change to the engine (new air
filter, new component, etc.), you need to operate the engine long enough for
the PCM to make the necessary updates to the long and short period fuel trim
parameters before making any performance measurements. But back to my
original contention, a simple change in the filter is easily adjusted for my
the PCM. If it can't handle the change, you will get a check engine light.
If it can handle the change, the fuel economy will not be significantly
affected. The PCM will adjust the fuel trim to compensate. Changing to a K&N
air filter is no different than many other minor change that affects the
engine parameters (change in altitude, sensor drift, normal contamination of
the air filter, etc). I am not trying to argue about what may or may not
happen when you make radical changes that may require the PCM to be
modified.

Ed

"Michael Johnson" > wrote in message
...

> Here is a cold hard fact..... gas mileage deceases as an air filter
> becomes more restricted. If you plotted mileage verses the degree of
> filter restriction the resulting line would not be linear. Under light
> clogging there is little impact but as the filter efficiency decreases
> substantially so does mileage. You are confining you argument to the
> small zone where the air filter is still operating with a high efficiency.
> Even there, a trivial reduction in mileage is still a reduction. As the
> filter gets progressively dirtier the effect it has on mileage is further
> magnified.

For a modern fuel injected engine, if the filter becomes so restrictive that
it will effect the fuel economy, you will get a check engine light. If the
check engine light is not on, the changes are trivial enough for the PCM to
compensate for.

But I am not arguing that a highly restricted air filter won't affect fuel
economy. I am only arguing that a properly service air filter won't affect
fuel economy to a significant degree (meaning measurable) and that a K&N
will not provide a fuel economy advantage for a modern fuel injected engine
compared to a properly serviced paper element. The difference between a
clean K&N filter and a new paper filter is trivial. Both become more
restrictive as they accumulate contaminants. Whether a particularly dirty
K&N is more restrictive than a given paper filter is impossible to know. But
even K&N acknowledges that a dirty K&N is more restrictive than a new paper
element.

Regards,

Ed White

"Bob Willard" > wrote in message
...

> Maybe so, but repeating the same claim over and over does not impress me
> as much as seeing results of testing on a modern FIE engine would. Do you
> have a URL for such a test report? The URL you gave earlier did not
> contain any test data; only dogmatic statements.
> --
> Cheers, Bob

Where is the incentive for anyone to run such a test? Air filter
manufacturers know that the results are not going to prove that their filter
will improve fuel economy. It is much easier to reference unprovable, hand
picked Customer testimonials, and advice left over from 50 years ago. You
don't have to defend these in front of the FTC. And running such a test is
not trivial. There are many factors that affect day to day fuel economy. For
some factors, I am willing to make judgments based on consistent behavior
and fuel economy measurements over a long period of time for some changes
(tire pressure, regular vs. premium fuel, etc.). Unfortunately, air filter
restriction is not one of the things I think I can personally evaluate. I
posted the fuel economy of my Nissan Frontier over the last 47,000 miles in
1000 mile blocks. Even Michael Johnson wasn't able to pick out when the air
filter was changed.The US EPA has a program to test fuel saving devices. No
one has submitted an air filter like a K&N for evaluation.

All sort of gas saving devices are advertised based on Customer
testimonials. Even K&N does this, but they are careful not to make the claim
themselves in writing. Given the high cost of fuel, don't you think K&N
would be willing to invest a few thousand dollars to run verifiable tests to
prove their filters improve fuel economy, if they really did? Don't you
think it would be worth million in sales to K&N if they could claim that the
US EPA has verified that K&N air filters improve fuel economy? K&N is now
running commercial touting the environmental benefits of K&N (based on
reusing the filter versus replacing paper filters). Wouldn't being able to
claim even a 2% fuel economy improvement be a much more powerful sales
incentive? Wouldn't Ford and GM install K&N air filters as standard if they
would improve fuel economy by 1% or 2%? Ford, Honda, and Toyota are all
changing to 0W20 oil because it can provide a 0.5% fuel economy improvement.
Ford actually sells (or sold) Foci with "lifetime" air filters. I posted a
link to a Visteon paper that discussed the design of these filters. There
was no problem with excess restriction in over 100,000 miles of use.

Final summary

- There is no technical reason to believe that a properly serviced K&N air
filter will improve fuel economy when compared to a properly serviced paper
air filter for modern fuel injected engines (modern being since 1996)

- K&N may or may not provide a power increase at wide open throttle. I am
not making that argument

- If K&N air filters actually provided a fuel economy benefit they would be
standard on new cars and K&N would have them evaluated by the EPA

- Customer testimonials are not verifiable (Customers have also claimed
splitfire spark plugs, vortex inducers, acetone, and magnets improve fuel
economy).

- Claims that a dirty air filter reduce fuel economy by up to 10% are based
on carbureted engines from 40 years ago. Even then this was an extreme claim
but there was a basis in fact. For a carbureted engine, a very dirty air
filter acts like a choke and screws up the A/F ratio. Modern fuel injected
engines are not affected in this manner. Air filter manufacturers are more
than willing to allow this "old advice" to circulate. Why would they try to
correct it? What filter manufacturer doesn't want to sell more filters. And
interestingly, there is actually a downside to changing your filter too
often. New filters don't filter as well as old filters. Even K&N makes the
case that K&N filter better after they are contaminated - at which point
they are as restrictive as a paper filter.

- If a dirty filter actually reduced fuel economy by a measurable amount,
the check engine light would be on.

- The effect of air filter contamination is drastically different at WOT
than it is at a cruise. The higher the flow rate, the greater the pressure
drop for a given level of restriction. At a steady cruise the pressure drop
across the air filter is trivial. If the restriction is so great as to be
non-trivial at cruise, the car is going to run like s*!t when you floor it -
and probably the check engine light will be set.

Ed

"Michael Johnson" > wrote in message
...

> Go find one yourself if it is that important to you. It isn't my job to
> do your research. Find me a reference that says a dirty air filter
> doesn't cause ANY DROP in gas mileage.

I posted a link to the Consumer Reports article that claimed it made no
significant difference. You nit picked that because they said no significant
difference. Absolute claims for fuel mileage are rarely made. No significant
difference implies, no measurable difference as far as I am concerned. If
you can measure the difference, is there a difference? I am certain if there
was a measurable difference CR would have provided the results.

This whole thread got started because I claimed that a K&N filter would not
provide a fuel economy improvement compared to a properly serviced paper
filter. I stand by that claim. I've seen no data or even a good argument
that refutes that claim.

Ed

C. E. White wrote:
> "Michael Johnson" > wrote in message
> ...
>
>> Go find one yourself if it is that important to you. It isn't my job to
>> do your research. Find me a reference that says a dirty air filter
>> doesn't cause ANY DROP in gas mileage.
>
> I posted a link to the Consumer Reports article that claimed it made no
> significant difference. You nit picked that because they said no significant
> difference. Absolute claims for fuel mileage are rarely made. No significant
> difference implies, no measurable difference as far as I am concerned. If
> you can measure the difference, is there a difference? I am certain if there
> was a measurable difference CR would have provided the results.

No significant difference is still a difference. Only CR knows what
that means. I take it as a difference they deemed worth noting.

> This whole thread got started because I claimed that a K&N filter would not
> provide a fuel economy improvement compared to a properly serviced paper
> filter. I stand by that claim. I've seen no data or even a good argument
> that refutes that claim.

Nor have I seen any evidence that disproves it.

C. E. White wrote:
> "Michael Johnson" > wrote in message
> ...
>
>> Here is a cold hard fact..... gas mileage deceases as an air filter
>> becomes more restricted. If you plotted mileage verses the degree of
>> filter restriction the resulting line would not be linear. Under light
>> clogging there is little impact but as the filter efficiency decreases
>> substantially so does mileage. You are confining you argument to the
>> small zone where the air filter is still operating with a high efficiency.
>> Even there, a trivial reduction in mileage is still a reduction. As the
>> filter gets progressively dirtier the effect it has on mileage is further
>> magnified.
>
> For a modern fuel injected engine, if the filter becomes so restrictive that
> it will effect the fuel economy, you will get a check engine light. If the
> check engine light is not on, the changes are trivial enough for the PCM to
> compensate for.
>
> But I am not arguing that a highly restricted air filter won't affect fuel
> economy. I am only arguing that a properly service air filter won't affect
> fuel economy to a significant degree (meaning measurable) and that a K&N
> will not provide a fuel economy advantage for a modern fuel injected engine
> compared to a properly serviced paper element. The difference between a
> clean K&N filter and a new paper filter is trivial. Both become more
> restrictive as they accumulate contaminants. Whether a particularly dirty
> K&N is more restrictive than a given paper filter is impossible to know. But
> even K&N acknowledges that a dirty K&N is more restrictive than a new paper
> element.

Logic dictates that if a dirty filter causes a reduction in fuel mileage
then the degree to which it is clogged determines the degree of the
mileage reduction. The mileage reduction doesn't materialize at a
defined point near the end of a filter's life span. The reduction
starts to occur the minute the new filter is used and gets progressively
worse.