The heavily touted 4.6L 3V motor in the new Mustang GT comes
with a big jawbreaker stuck deep in its throat. The factory
has it choking on its' own air inlet system. Restrictive air
boxes and silencers have become the Achilles heel of Mustangs.
The previous generation had the rubber fender insert and the
5.0L era Mustangs had the funky looking plastic contraption.
The practice of immediately removing these things has became
so notorious it is classified as a "free horsepower mod".
Even the most green of Mustang enthusiasts know to rip their
silencers out the minute they turn the corner from the dealer's
For the '05 the restriction comes in several areas. First
and foremost is the 2" square opening from which air
enters into the air-box. How the car can lay down over 250
horsepower to the wheels sucking air through this swizzle
stick of an inlet is mind blowing. Once the air makes it past
the filter and mass-air meter (integrated into the air-box
lid) it encounters the most severe restriction we've seen
to date on any Mustang, the carbon filter. This rigid plastic
piece resembles a tightly rolled up piece of corrugated cardboard.
It performs an emissions function of trapping gasoline fumes
that might be in the intake system.
The final restriction is the harsh bend in the throttle body
duct. Ford has always used the pre-formed accordion shaped
bellows to connect between the mass-air meter and throttle
body. In our experience there has always been some power to
be found by straightening this out, and perhaps even increasing
the diameter - especially once you start adding other mods.
What separates the new Mustang's breathing problems from that
of past generations is that on the '05 you can't just pull
out the silencer or slap on a big conical air filter for decent
power gains. The mass air meter and computer in the new Mustang
is so sensitive to airflow changes that even removing just
the carbon trap from the inlet tube results in a significant
leaning out of the air-fuel ratio. Do that and a K&N filter
and the engine will go lean enough to throw a check-engine
light and trouble code.
If this sounds like a nightmare just talk to Lee Bender, owner
of C&L Performance, the mass-air meter and inlet specialists.
Usually C&L's products bolt right on, yield impressive
gains, and require no tuning of the engines PCM. However,
early on in their R&D process and dyno testing they realized
the '05 was a different beast. The slightest changes in the
factory air intake system would change the air-fuel ratio
significantly. To make matters more complicated, the first
couple dyno pulls immediately after a change would show no
ill effects. Subsequent pulls would however show undesirably
lean conditions, as if the engine management system was picking
up the airflow change and improperly adapting to it. It didn't
matter how slight the change, the engine ultimately didn't
like it and power gains were less than optimal- and keep in
mind C&L is using the same diameter mass-air meter housing
and the factory sensor.
After beating their head against the wall the C&L team
realized the '05 required some computer re-tuning to go along
with the hardware upgrade. They teamed up with Diablosport
who had also been at work developing an '05 tune for their
Predator tuner product. The Trueflow system consists of a
cast aluminum inlet tube and mass-air meter, a big K&N
conical air filter and heat shield, and is bundled with a
Diablo Predator tuner with a specific C&L 2005 Mustang
tune. We had the opportunity to play with this kit on the
dyno and at the track, here is how it performed.
With the '05 Mustangs mass-air meter integrated into the
air-box lid, removing the entire air-inlet system is merely
a five minute process.
Using a 10mm socket, remove the single bolt securing the
air filter housing to the fender.
Disconnect the mass-air sensor plug as shown.
Squeeze to release the PCV system hose connection.
Loosen the clamp securing the stock rubber inlet bellows
to the throttle body.
The entire factory air-inlet system can be removed now
as a unit.
Using the provided Torx security bit remove the screws
securing the mass air sensor cartridge.
Carefully transfer the sensor into the new C&L mass
air meter and secure with the factory Torx screws.
We prefer to pre-assemble the C&L system on the work
bench, then simply connect it to the throttle body. The
filter shield is secured to the fender using the same
bolt removed in step 2. C&L includes a bracket to
further secure the mass-air housing to the motor if desired.
Reconnect the mass-air connector and PCV hose.
With the engine off connect the Diablo Predator to the
vehicles OBD-II service port. On the '05 it is located
directly under the driver side dash. Follow the on-screen
instructions to program the vehicles computer with the
C&L specific tune. Further enhancements to the tune
can also be made, as we detail in this article.
The first opportunity to test the C&L system came at
a Wednesday night Bracket event at our local track. We generally
don't prefer testing at bracket events because you typically
get very few runs before you are into elimination rounds. To
make matters worse our plan to run the '05 on slicks fell through
due to the 15" steel wheels not clearing the disc brake
calipers. So we did the best we could on the stock radials.
With only a total of three runs to acquaint ourselves with the
new car we managed a best run in bone stock form of 14.42 @
99.68 mph. This came on an embarrassing sixty-foot time of 2.39.
Disappointed that we didn't achieve the stock-13's-on radials
that so many '05 owners around the country are reporting, we
chalked it up to the poor traction and lack of seat time in
the new platform. With elimination rounds looming we quickly
installed the C&L kit and reprogrammed the computer with
2.5mph gains at the track gave
quick confirmation the C&L/Diablo air intake and tune
was for real.
We only got one pass with the C&L system in place, however
the results proved to be a clear indication this was no ordinary
duct and filter kit. With a slightly better 2.10 sixty-foot
time the '05 tripped the lights at 13.86 seconds and 102.54
mph. We were dying to make another all out pass to see if we
could get the ET lower, however the announcement came that it
was time to dial-in and begin bracket rounds. We played it safe
and dialed in at 13.8, and managed to run a 14.0@102. At least
we backed up the trap speed gains with the C&L. Continue