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Mustang GT and K&N air charger



 
 
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  #141  
Old February 8th 08, 03:55 PM posted to rec.autos.makers.ford.mustang
C. E. White[_1_]
external usenet poster
 
Posts: 933
Default Mustang GT and K&N air charger


"My Name Is Nobody" > wrote in message
news:vpKqj.6861$Qj3.1135@trndny07...

>> There is no reason that it should be. In fact, if the feedback
>> system is functioning as designed there should be very little
>> change in the A/F ratio no matter what you do to the intake. If the
>> PCM can't maintain the proper A/F ratio, then it should set the
>> check engine light.
>>
>> Ed

>
> BULL****!


You love to use that term, yet I would argue you keep dishing out the
same references without really considering the facts. Tell me why you
think just changing the air filter (not the complete air intake
system) can effect fuel mileage. Two of your three references were
ads, so you should view them with suspicious. All three were concerned
with WOT performance, not normal everyday driving. Trying to predict
changes in gas mileage based on WOT performance tests is risky at
best.

> I've posted three different links to documented dyno tuning of new
> FORD cars with simple new air intake systems, that exceed the PCM's
> ability to properly adjust the air fuel ratio without changing the
> programming. There are many many more links showing the same. If
> indeed these peoples information (dyno charts with A/F ratios)
> indicating a filter changing DOES cause the PCM to run the air fuel
> ratio TOO LEAN, is held up against your undocumented insistences
> that the PCM can maintain the proper A/F ratio, seems like you are
> wrong.


The first reference you cite, really just an ad
,http://www.allfordmustangs.com/revie...hp/product/394
was ridiculous. I have repeatedly pointed out that it is inconsistent.

Point 1 - They are measuring performance at WOT. The vehicle runs open
loop at WOT, so the PCM is not adjusting the A/F based on feedback at
that point. For real world situations, this is handled by the long
term fuel trim. However, in order to learn the long term fuel trim,
you have to actually complete a drive cycle.

Point 2 - I doubt if what they say is even true (or at least not in
sense that you interpret it). The ad provided no numbers, it just made
a BS statement - "Even when replacing the air filter ONLY to a higher
flow assembly, the air/fuel ratio leans out at an alarming rate." What
is the air filter assembly? Just the actual filter element, or
everything in front of the throttle body? What is an alarming rate?
How can "replacing the air filter assembly ONLY to a higher flow
assembly" lean out the A/F ratio at an "alarming rate" when in the
same article they claim that replacing the air filter assembly won't
result in a mixture "lean enough to cause engine durability concerns."
If there are no durability concerns (at WOT by the way) what the heck
is "alarming."

Point 3 - Mostly the ad is talking about a complete intake system
replacement, including the MAF. Certainly if you start screwing around
with the MAF you may need to retune the PCM. I never made any claims
about what happens when you do things like that. I am only talking
about air filters in the OE intake assembly. Once you start screwing
with the other components (particularly the MAF), all bets are off.

Your second reference was another thinly disguised ad
http://musclecarnews.tenmagazines.co...ticle&aid=3684 :

Point 1 - There are no charts that say anything about FUEL ECONOMY.

Point 2 - There are no charts showing that changing the air filter
ALONE will cause the engine to run to lean. And although the charts
do show changes in A/F ratio when the COMPLETE AIR FILTER ASSEMBLY is
changed (again the charts are showing only WOT operation), I don't see
anything alarming. Without data at part throttle operation and after
the PCM has learned the long term fuel trim, I can't see where the
information presented can be used to say anything about the effect
changing the air filter has on fuel economy.

Point 3 - I suspect they did not bother to complete a drive cycle in
between the tests. Unless you compete a drive cycle, the PCM does not
have a chance to learn new long term fuel trim parameters. Since they
are measuring things at WOT (i.e., not in feedback mode), you need to
complete a drive cycle to make sure the PCM has learned the correct
long term fuel trim so that the A/F ratio will be corrected for open
loop operation.

Your third reference
http://www.edmunds.com/insideline/do...ticleId=118839 was
dealing with performance, not fuel economy. I agree that a restricted
air filter can reduce maximum power. So, I have no problems with this
article.

Ed


Ads
  #142  
Old February 8th 08, 09:15 PM posted to rec.autos.makers.ford.mustang
My Name Is Nobody
external usenet poster
 
Posts: 475
Default Mustang GT and K&N air charger


"C. E. White" > wrote in message
news:47ac6ddf@kcnews01...
>
> "My Name Is Nobody" > wrote in message
> news:vpKqj.6861$Qj3.1135@trndny07...
>
>>> There is no reason that it should be. In fact, if the feedback system is
>>> functioning as designed there should be very little change in the A/F
>>> ratio no matter what you do to the intake. If the PCM can't maintain the
>>> proper A/F ratio, then it should set the check engine light.
>>>
>>> Ed

>>
>> BULL****!

>
> You love to use that term, yet I would argue you keep dishing out the same
> references without really considering the facts. Tell me why you think
> just changing the air filter (not the complete air intake


OH Fer Crying out loud! I've told you no less than six times!!!
Yes that term is perfectly applicable here. You are blowing smoke up
everyone's ass on this issue, and somehow you expect no one will call you on
your BULL****!

I logged every single fuel fill up and all maintenance (all done by me)
75,000 miles on a new car, both before and after a simple air filter element
change in the stock air box, with ZERO other changes.

Before air filter element change 7~25,000 miles with a very consistent 24.5
mile per gallon fuel mileage.
After air filter element change 25,000~75,000 miles with a very consistent
26.5 mile per gallon fuel mileage.

All NORMAL everyday mixed highway / surface street commuter miles! Near
ZERO WOT!












> system) can effect fuel mileage. Two of your three references were ads, so
> you should view them with suspicious. All three were concerned with WOT
> performance, not normal everyday driving. Trying to predict changes in gas
> mileage based on WOT performance tests is risky at best.
>
>> I've posted three different links to documented dyno tuning of new FORD
>> cars with simple new air intake systems, that exceed the PCM's ability to
>> properly adjust the air fuel ratio without changing the programming.
>> There are many many more links showing the same. If indeed these peoples
>> information (dyno charts with A/F ratios) indicating a filter changing
>> DOES cause the PCM to run the air fuel ratio TOO LEAN, is held up against
>> your undocumented insistences that the PCM can maintain the proper A/F
>> ratio, seems like you are wrong.

>
> The first reference you cite, really just an ad
> ,http://www.allfordmustangs.com/revie...hp/product/394 was
> ridiculous. I have repeatedly pointed out that it is inconsistent.
>
> Point 1 - They are measuring performance at WOT. The vehicle runs open
> loop at WOT, so the PCM is not adjusting the A/F based on feedback at that
> point. For real world situations, this is handled by the long term fuel
> trim. However, in order to learn the long term fuel trim, you have to
> actually complete a drive cycle.
>
> Point 2 - I doubt if what they say is even true (or at least not in sense
> that you interpret it). The ad provided no numbers, it just made a BS
> statement - "Even when replacing the air filter ONLY to a higher flow
> assembly, the air/fuel ratio leans out at an alarming rate." What is the
> air filter assembly? Just the actual filter element, or everything in
> front of the throttle body? What is an alarming rate? How can "replacing
> the air filter assembly ONLY to a higher flow assembly" lean out the A/F
> ratio at an "alarming rate" when in the same article they claim that
> replacing the air filter assembly won't result in a mixture "lean enough
> to cause engine durability concerns." If there are no durability concerns
> (at WOT by the way) what the heck is "alarming."
>
> Point 3 - Mostly the ad is talking about a complete intake system
> replacement, including the MAF. Certainly if you start screwing around
> with the MAF you may need to retune the PCM. I never made any claims about
> what happens when you do things like that. I am only talking about air
> filters in the OE intake assembly. Once you start screwing with the other
> components (particularly the MAF), all bets are off.
>
> Your second reference was another thinly disguised ad
> http://musclecarnews.tenmagazines.co...ticle&aid=3684 :
>
> Point 1 - There are no charts that say anything about FUEL ECONOMY.
>
> Point 2 - There are no charts showing that changing the air filter ALONE
> will cause the engine to run to lean. And although the charts do show
> changes in A/F ratio when the COMPLETE AIR FILTER ASSEMBLY is changed
> (again the charts are showing only WOT operation), I don't see anything
> alarming. Without data at part throttle operation and after the PCM has
> learned the long term fuel trim, I can't see where the information
> presented can be used to say anything about the effect changing the air
> filter has on fuel economy.
>
> Point 3 - I suspect they did not bother to complete a drive cycle in
> between the tests. Unless you compete a drive cycle, the PCM does not have
> a chance to learn new long term fuel trim parameters. Since they are
> measuring things at WOT (i.e., not in feedback mode), you need to complete
> a drive cycle to make sure the PCM has learned the correct long term fuel
> trim so that the A/F ratio will be corrected for open loop operation.
>
> Your third reference
> http://www.edmunds.com/insideline/do...ticleId=118839 was dealing
> with performance, not fuel economy. I agree that a restricted air filter
> can reduce maximum power. So, I have no problems with this article.
>
> Ed
>



  #143  
Old February 10th 08, 09:46 PM posted to rec.autos.makers.ford.mustang
Ed White[_2_]
external usenet poster
 
Posts: 89
Default Mustang GT and K&N air charger


"My Name Is Nobody" > wrote in message
news:UL2rj.4$Uq4.2@trndny02...
>
> "C. E. White" > wrote in message
> news:47ac6ddf@kcnews01...
>>
>> "My Name Is Nobody" > wrote in message
>> news:vpKqj.6861$Qj3.1135@trndny07...
>>
>>>> There is no reason that it should be. In fact, if the feedback system
>>>> is functioning as designed there should be very little change in the
>>>> A/F ratio no matter what you do to the intake. If the PCM can't
>>>> maintain the proper A/F ratio, then it should set the check engine
>>>> light.
>>>>
>>>> Ed
>>>
>>> BULL****!

>>
>> You love to use that term, yet I would argue you keep dishing out the
>> same references without really considering the facts. Tell me why you
>> think just changing the air filter (not the complete air intake

>
> OH Fer Crying out loud! I've told you no less than six times!!!


Well, you have repeated the same claim six times. It would help if you
posted your personal data that supports this claim. I have explained why the
ads you referenced were irrelevant to the discussion.

> Yes that term is perfectly applicable here. You are blowing smoke up
> everyone's ass on this issue, and somehow you expect no one will call you
> on your BULL****!


You have never tried to explain why just changing the air filter should
result in a large increase in fuel economy. You posted several thinly
disguised ads that were testing things at WOT. They were not relevant to the
discussion of the fuel economy of an otherwise stock vehicle's fuel economy
in normal day to day operation. You also claimed you have personal
documentation to support the idea. Maybe you do. Without the data and
knowledge of what was changed, I cannot comment on your particular
situation. I certainly would not dispute the data for your personal case.
However, in general what your are claiming cannot be true. You must have
some reason for believing that changing the air filter improved the fuel
economy. Under normal driving conditions, the A/F ratio is adjusted by the
PCM in response to the O2 sensor. No matter what happens in the intake
system, the PCM should be able to adjust the A/F ratio back to the desired
value. So I think it would be difficult to claim that changing the air
filter changed the A/F ratio in a way that would significantly affect fuel
economy. And unless you are at WOT, the restriction across the air filter is
not a determining factor in intake system pumping losses. For a less than
"maximum" power level, the air flow into the engine is controlled to less
than maximum. It is the total restriction from the air intake to the back of
the throttle plate that matters. It is largely not relevant whether the
restriction is at the air filter or the throttle plate (unless you are at
WOT). And again, the air restriction of a properly service air filter is
trivial. One of your sources provides back up for this. See
http://www.cnlperformance.com/images...ACER_Flow2.jpg . Even at
WOT and an impossibly high air flow rate, the air flow restriction of the
stock intake is trivial.

> I logged every single fuel fill up and all maintenance (all done by me)
> 75,000 miles on a new car, both before and after a simple air filter
> element change in the stock air box, with ZERO other changes.
>
> Before air filter element change 7~25,000 miles with a very consistent
> 24.5 mile per gallon fuel mileage.
> After air filter element change 25,000~75,000 miles with a very consistent
> 26.5 mile per gallon fuel mileage.
>
> All NORMAL everyday mixed highway / surface street commuter miles! Near
> ZERO WOT!


Most of my vehicles have shown improvements in fuel economy over time as
they have been broken in. My 2 Expeditions (a 1997 and a 2003). took the
longest to achieve maximum fuel economy. The 1997 average 13.84 mpg for the
first 25 k miles and 14.29 mpg for the next 25 k miles. The 2003 averaged
14.7 mpg for the first 25 k miles and 15.13 for the next 25 k miles. For
both vehicles this represents about a 3% increase in fuel economy, and there
were no changes other than routine maintenance. This is not as dramatic as
your claimed 8% improvement, but I think you can get the idea that you might
need to look closer at your data.

I assume your data also shows a gradual decrease in fuel economy between air
filter changes? Or is it your claim that you changed to the lower
restriction filter, got a huge fuel economy improvement that you attributed
to the filter, and that it stayed steady over time, showing no decline
between air filter changes (or cleanings)? If it doesn't show a decrease
between filter changes (or cleanings) why not? If you believe changing to
low restriction air filter increased the fuel economy by 8%, you must also
believe that the fuel economy decreases as the filter becomes contaminated.
I've never seen any indication that this is the case for any of my modern
vehicles (again my data is at
http://home.mindspring.com/~cewhite3...nomy_study.xls )
..

Finally, does your claim of an 8% improvement in fuel economy pass the
reasonableness test? Do you thing Ford, or GM, or Toyota wouldn't change to
an air filter that improved fuel economy by 8%? How great would that be in
their drive to meet CAFE requirements?

Ed


  #144  
Old February 11th 08, 05:57 AM posted to rec.autos.makers.ford.mustang
Ironrod
external usenet poster
 
Posts: 80
Default Mustang GT and K&N air charger


"My Name Is Nobody" > wrote in message
news:qAVpj.2934$f73.1418@trndny08...
>
> "Ironrod" > wrote in message
> ...
> >
> > "Michael Johnson" > wrote in message
> > ...
> >> Ironrod wrote:
> >> > "Michael Johnson" > wrote in message
> >> > ...
> >> >> C. E. White wrote:
> >> >>> "Michael Johnson" > wrote in message
> >> >>> ...
> >> >>>
> >> >>>> Haven't we beat this to death between us? I was replying to WF
> >> >>>> because you and I are never going to agree on this issue.
> >> >>> We beat it to death long ago. I just can't turn away. You clearly
> >> >>> don't understand how modern feedback fuel injection systems work

and
> >> >>> because of this you are drawing bad conclusions. Foolishly, I hope

I
> >> >>> can make a subtle change in my arguments so that you can understand
> >> >>> that unless you are at wide open throttle, the restriction of the

air
> >> >>> filter is largely irrelevant as far as the performance of the

engine
> >> >>> is concerned. Except at WOT, the throttle plate is the final
> >> >>> adjustment to the air flow rate. If you increase the restriction in
> >> >>> another part of the intake tract, you can open the throttle a

little
> >> >>> more to get the same overall flow restriction. This doesn't effect
> >> >>> fuel economy because the PCM has the ability to correct the A/F

ratio
> >> >>> based on the output of the O2 sensors (as long as the restriction

is
> >> >>> not so gross as to set the malfunction indicator). The system is
> >> >>> designed to be able to compensate for changes like increasing air
> >> >>> filter restriction, drift in the response of the various sensors,
> >> >>> altitude, etc. Compared to other changes over time, a minor

increase
> >> >>> in the flow restriction related to the air filter is trivial. Until
> >> >>> you understand this, you'll continue to draw the wrong conclusion.
> >> >> Ed, let it go. Mileage doesn't drop from a dirty filter at some

> > magical
> >> >> point. It is a gradual reduction that gets progressively more
> >> >> noticeable as the filter collects more dirt.
> >> >
> >> > That's not true, there is a knee point in the curve. As long as the

> > filter
> >> > is capable of delivering more air than the engine is capable of

> > demanding
> >> > then the percentage of blockage is not a factor. Once the blockage

> > exceeds
> >> > a certain amount then you will experience a power roll off as you

> > approach
> >> > WOT. As far as mileage is concerned there should be little or no

> > change,
> >> > (at cruising speeds) as the fuel mixture is relatively constant

because
> > of
> >> > the electronics.
> >>
> >> The air filter is a restriction to air flow under ALL CONDITIONS. This
> >> is an undeniable fact. As it gets dirty is becomes a larger and larger
> >> restriction. This restriction affects performance under all

conditions.
> >> How much varies with the conditions and the efficiency of the filter.
> >> An engine is an air pump. Anytime the pump can move more air it

makes
> >> more power and becomes more efficient.

> >
> > Approach it this way, imagine walking down a hallway 10 foot square with
> > its
> > sides converging. As you move towards the end the corridor gets narrower
> > until you can no longer pass. Now as long as you remain in the portion

of
> > the hallway that is as large or larger than you are, you can run back

and
> > forth at whatever speed you feel like. It won't be until you reach the
> > point where your start rubbing up against the walls that your forward
> > progress will be slowed. So goes the Air Filter, as it becomes dirtier
> > the
> > walls close in, so to speak, but still you can move about freely. It
> > won't
> > be until after the walls have narrowed to the point that you can no

longer
> > walk upright that your movement is significantly impeded.
> >
> >

> Your example assumes that the clean filter provides ZERO restriction, that
> just isn't so.
>
>

No, I am saying that the restriction remains constant throughout its
service life, further that when the filter reaches the end of its service
life you will only feel it at the engines top end, remember in this example
I'm just talking about the air filter. Now when you take the entire intake
tract as a whole then the walls of my hypothetical corridor are by necessity
only as wide as the engine's air flow requirements need them to be. The
variable, of course, is the throttle plate which can only reduce the intake
restriction by a specific percentage determined by the engine load. Opened
wider the engine goes faster, closed it goes slower. Change the filter or
remove it entirely then the throttle plate must be adjusted (by means of
your foot) to restrict the air flow down to only the required amount. No
more no less.


  #145  
Old February 16th 08, 10:37 AM posted to rec.autos.makers.ford.mustang
Ironrod
external usenet poster
 
Posts: 80
Default Mustang GT and K&N air charger


Nobody" > wrote in message
news:XnAlj.5641$5h6.763@trndny09...
>
> "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
> >

>
> A good friend of mine once told me never to argue with a fool, because

after about five minutes it becomes impossible to tell who is who. Its
getting to be the same with this thread, A point that I think was
overlooked is that nobody pointed out that at normal idle the intake is
almost 100% restricted, (closed). The almost part being the small amount of
air needed supply the idle circuit. The engine changes speed (RPM) by
removing that restriction to allow for more air as the demand increases.
Point of fact, if that restriction isn't there then the engine will continue
to spin up until it self-destructs. You need restriction in order to
control the engine output.
Now while I've never measured it I would suspect that the intake is still
restricted by over 90% even when cruising at 70.
Mileage is not effected solely by air flow changes, what has to change is
the air/fuel ratio. If sufficient air is flowing to feed the fire then
you're golden. With current electronics measuring the air coming in, the
exhaust going out and adjusting the fuel feed in between the air/fuel ratio
is held static.
Another misconception is that the engine has to work harder in order to suck
the air through a dirty filter than it does through a clean one. It
doesn't. (Hard to believe I know). The engine isn't sucking air through
the filter, it is sucking it past the throttle plate, which is almost
completely closed to start with. (If it wasn't the engine would spin up out
of control.) Air flows across the filter as a result of the pressure drop.
The amount of restriction needed to maintain a certain RPM at a certain load
is fixed. Restriction of the air filter, intake, throttle body, manifold &
outside pressure are all cumulative but overall pressure drop is the same
for a specific load. An example, if you were measure the pressure drop
between the outside air and just aft of the throttle body you would have a
number that would directly correlate with how much effort the engine is
expending to suck the air in. Remove the entire intake tract so there just
a bare throttle body and take the measurement again you would still have the
exact same number. In other words the engine worked just as hard to suck
air through the intake as it did to suck it straight out of the atmosphere.
The throttle would be slightly more closed to compensate for the loss of the
restriction caused by the missing components but the overall result would
remain the same.


 




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