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