Air filter and mpg.

In article
domain>,
Whoever > wrote:

> Bzzt. Wrong. Try this document:
> http://www.google.com/url?sa=t&ct=re...shop101.com/fo
> rms/h44.pdf&ei=IDwnQ-CuM8-YYYmbiIIO
>
> From the document:
> "Because Long FT is part of the basic injection duration, it affects
> injection duration in closed and open loop"

For this to be relevant and lend any support to your argument,
open loop operation would have to have some authority on long
term fuel trim. It doesn't.

> How often do most drivers actually use WOT?

Quite often.
WOT on almost all systems is defined as any TPS voltage above 2.5
volts.
(that's roughly half throttle)

On Wed, 14 Sep 2005, Bill Putney wrote:

> >>>What you are doing, Mr. Whoever, is yacking-off...
> >>
> >>And if he's using a Macintosh...

> > Naw, that's when Macintologists start preaching the Gospel According to
> > Jobs.

> Man - I'm disappointed - you missed the joke.

Naw, I didn't. I just didn't blurt out the punchline, is all.

"Maccin' off". There.

On Wed, 14 Sep 2005, aarcuda69062 wrote:

> Whoever > wrote:

> > My point is that the dirty filter is equivalent to a slightly closed
> > throttle:
>
> No it isn't. You can't claim one aspect of function and totally ignore
> the others.

Apparently s/he's not one of those types who let facts stand in his/her
way.

> > closed throttle = reduced (absolute) manifold pressure (it also
> > depends on engine speed, but for the sake of this limited discussion
> > we assume a constant speed)
>
> Sorry, "limited discussion' serves no useful purpose other than to
> confuse the issue.

Geeze, Neil, can't you have a debate without resorting to ad hominems and
gross exaggeration? ;-)

> > But a dirty filter does not require infinite compensation.
>
> How dirty is dirty?

Dirty! Y'know, dirty!

In article
ich.edu>,
"Daniel J. Stern" > wrote:

> On Wed, 14 Sep 2005, aarcuda69062 wrote:
>
> > Whoever > wrote:
>
> > > My point is that the dirty filter is equivalent to a slightly closed
> > > throttle:
> >
> > No it isn't. You can't claim one aspect of function and totally ignore
> > the others.
>
> Apparently s/he's not one of those types who let facts stand in his/her
> way.

The phrase "knows enough to be dangerous" comes to mind...

> > > closed throttle = reduced (absolute) manifold pressure (it also
> > > depends on engine speed, but for the sake of this limited discussion
> > > we assume a constant speed)
> >
> > Sorry, "limited discussion' serves no useful purpose other than to
> > confuse the issue.
>
> Geeze, Neil, can't you have a debate without resorting to ad hominems and
> gross exaggeration? ;-)

So much for the 'kinder, gentler' Neil.

> > > But a dirty filter does not require infinite compensation.
> >
> > How dirty is dirty?
>
> Dirty! Y'know, dirty!

Oh, *that* dirty!

On Wed, 14 Sep 2005, aarcuda69062 wrote:

> Whoever wrote:

> > > > But a dirty filter does not require infinite compensation.
> > >
> > > How dirty is dirty?
> >
> > Dirty! Y'know, dirty!
>
> Oh, *that* dirty!

At least I don't *think* he meant the dirty that comes between twenny-nine
and dirty-one.

Daniel J. Stern wrote:
> On Wed, 14 Sep 2005, aarcuda69062 wrote:
>
> > Whoever wrote:
>
> > > > > But a dirty filter does not require infinite compensation.
> > > >
> > > > How dirty is dirty?
> > >
> > > Dirty! Y'know, dirty!
> >
> > Oh, *that* dirty!
>
> At least I don't *think* he meant the dirty that comes between twenny-nine
> and dirty-one.

I haven't read all the posts in this string, but I'd bet that once the
filter got too dirty for the computer to correct for, it would key the
check engine light and you'd store a code. Up to that point, you
should be fine, and mileage shouldn't be effected.

Marvin Stockman

On Sun, 18 Sep 2005 wrote:

> I haven't read all the posts in this string

....but you're sure you know the answer...

> but I'd bet that once the filter got too dirty for the computer to
> correct for, it would key the check engine light and you'd store a code.
> Up to that point, you should be fine, and mileage shouldn't be effected.

OK, that's an imaginative, special and unique guess. Thanks for
sharing it with us. Now, go look up the difference between "effect" and
"affect".

First, "dirty" needs to be defined! Is it "cosmetic" or
"restrictive"??? Highly significant differences!!!

Each air filter element is designed to support a particular service life
in its intended use, which can relate to some highly skewed filter sizes
versus engine air flow requirements. In the GM side of things, by
observation, a garden variety car which will see a lot of fleet (rent
car company) sales, can have a huge air filter element for a 3.1L V-6
whereas a 4.6L Northstar Cadillac will have a filter that's less than
1/2 that size.

There has been some informative discussions on engine air filters in the
www.bobistheoilguy.com message board website. Engine oil analysis (one
thing many participants on that board like to do) tends to support
higher silica levels in the oil of engines equipped with the beloved K&N
air filter elements. Another test reveals that the factory GM Duramax
air filter element flows better and has higher particle retention (in
standardized tests) than a K&N replacement element.

GM TSBs also mention the oil in the K&N fouling the computer sensors
downstream in the air flow from the K&N air filter too. A "fouled"
sensor that will throw a code too!

In general, a fresh air filter will always flow better than a "used"
one, the degree of longevity of the filter's higher flow life will
depend on the operational environment of the vehicle. It can also
depend on the filter media too. I was short on funds and bought a less
expensive filter (for the popular 13x3" open element air cleaner) and it
turned "dirty" quickly, yet the Fram I got to replace it is still
"white".

IF the filter element size/flow situation is on the smaller side of
things, a small amount of "wear" will put things into the "decreased
performance" area quickly (kind of like the 3.1L V-6 and Northstar V-8
illustration), but if the filter is oversized for the application (for
longer service life of the element), so how much of an affect the
"dirty" filter has on performance is highly variable and NOT
particularly related to brand or type (other than the oil issue
previously mentioned).

IF the filter element size/flow is on the "too small" side of things,
adding a higher flow element (i.e., K&N or Fram AirHog) might help
performance, BUT only if the orig setup is so far undercapacity that it
really makes a difference with the higher flow element.

"Dirty" air filters and performance and mpg? If the additionally
restricted air filter element will not flow enough air for the
particular throttle input, then more throttle input will be desired to
maintain a particular performance level of the vehicle. More throttle
input = more delta TPS signal = more fuel for a given result, even with
feedback loop operation of the fuel system. Just like in the "old
days", when lower manifold vacuum levels would kick in the "power
circuit" sooner than normal.

Fuel econony? We need to talk about cruise economy or city driving
economy, I suspect. At highway cruise, I suspect a dirty air filter
element would impact fuel economy very much, unless it was really
clogged up. In the city environemnt, where throttle position will
change much more frequently and accelerative bursts might be needed, I
suspect THAT's where you'll notice the difference in power and economy.

It's a given that the less throttle input it takes to achieve a desired
level of performance, fuel ecomomy will typically be better.

Many of the radio talk show hosts have to talk in generalitics more than
specifics. Giving the general listening public some general information
they can deal with in their daily lives is important, so what they say
in response to a question might not be applicable to all vehicles in all
situaitons per se. And the television car show operatives can also
"sell up" a particular product, which might well be an advertiser on
their show.

To me, the key thing is to consider their statements as "general"
statements rather than statements that would specifically apply to YOUR
vehicle only. End result, somebody somewhere will let a "service
professional" make a determination as to whether or not their air filter
element is "dirty" and needs changing. OR they'll check the restriction
gauge on their air filter housing (if equipped) to see if it's still
"green" or "red".

(Let the engine speed now return to idle!)

Enjoy!

C-BODY