New EFI and Heat
Last year Harley Davidson introduced a new Electronic Sequential Port Fuel
Injection (ESPFI) system on the 2001 line of Softail motorcycles. The
system combined the best features of EFI ideal fuel delivery at all
temperatures and altitudes-- with new technology that retains the hearty
rumble and "potato - potato" sound of the Harley V-Twin. The
same ESPFI system is now offered on 2002 Touring models.
Several key features differentiate the new ESPFI
system from the previous design, the most significant being the use of
speed density ( or intake manifold pressure) as the primary factory
in fuel control, rather
than throttle position.
A new EFI system graces all 2002 Harley
Davidson Touring models equipped with EFI. It uses speed density as the
primary factor in fuel control and ion-sensing knock detection (via the
two terminal sensor illustrated by the drawing) to monitor engine
performance. A new three-phase heat management system is also employed to
help keep the rider cool.
By measuring manifold pressure, intake air
temperature, engine temperature and throttle position on a per-cylinder,
the new Touring EFI system compensates for potential air leaks, calculates
real engine load (versus a theoretical load of throttle position only
systems) and is more sensitive to fuel control, particularly at lower
throttle levels. That's not all.
A closed loop idle control reads motor RPM to
control idle, thereby elimination problems associated with air leaks. Idle
on the new Touring models is set at 1000 RPM, however, a H-D dealer can
recalibrate idle between 800-1250 RPM. The new system used ion-sensing
technology to continuously monitor and adjust performance in accordance
with hot weather and fuel quality. And to reduce the complexity and
improve reliability of the new ESPFI, the return fuel line used on the
previous EFI system has been eliminated.
On the road, the benefits of the new ESPFI system
are undeniable. The familiar "potato-potato" sound flows from
the exhaust as pure as any 45-degree V-Twin from The Motor Company. There
are no hesitations or inconsistencies sometimes associated with improperly
tuned carburetors. Twist the throttle and the 14500cc motor responds
instantly. Fuel economy is generally 2-3 MPG better than carbureted
models, although mileage will vary depending upon conditions and riding
style, and ESPFI requires no jetting, no hassling with choke and idle
controls and smooth starts in all temperature conditions.
Complementing the new ESPFI induction is an
all-new, three-phase heat management system designed to keep riders
cooler. Based on engine temperature and the bike's condition (moving or
stationary), three different strategies are employed to manage engine heat
by automatically varying idle speed and fuel delivery.
The result is more consistent, cooler engine
operation and reduced heat felt by the rider. Heat management is possible
only with the new ESPFI-equipped models, and it's yet another hidden
technology inside Harley-Davidson Touring models like the Road King