VRFI Fuel Injection
Why is the VRFI auto-tuning
capability superior to competitive products?
Competitive systems such as the
and the new Dynojet®
claim to have auto-tuning capability. Prospective customers should ask whether
a given system meets two important criteria:
auto-tuning real-time and continuous? Real-time means that the system makes
immediate air/fuel ratio corrections based on oxygen sensor feedback.
Continuous means that the system makes corrections whenever it is running.
2. Can the user monitor, control, and override the
Any "feedback" system using a sensor to make corrections is subject to
operating regions where instabilities or errors exist.
system fulfills the first
criteria, it does offer
real-time and continuous auto-tuning. The new Power Vision®
system is neither real-time nor continuous. The user must log operating data
while the engine is running, download the data to a PC, apply the air/fuel
ratio corrections to a tuning file, and then reflash the engine control
module (ECM) with the modified tuning file.
Only the VRFI system meets
both criteria. 30 seconds after engine start, when the oxygen sensors have
warmed up, the VRFI system continually updates independent front and rear
cylinder air/fuel correction tables, referred to as the block learn
multiplier (BLM) tables. The BLM tables have the same cells (RPM rows and
throttle position columns) as the air/fuel ratio command table. Correction
values are in percent units. A value less than 100% means that fuel is being
taken out to correct a rich condition. A value greater than 100% mean that
fuel is being added to correct a lean condition. An actual BLM table is
shown below (the table is from our Twin-Cam TCFI system, but the VRFI
functions the same). Most of the values are between 90% to 110%, showing
that the system is now well tuned and just making small corrections. The
user can download the setup file from the VRFI at any time and monitor the
Part of the second criteria listed above
is the ability to control and override the auto-tuning corrections. Only the
VRFI system offers this capability on a cell-by-cell basis. You will notice
cells highlighted in blue with values 0 and 1. Closed loop feedback is
disabled in any BLM cells with value 0. This is useful in operating areas
where exhaust reversion effects may cause incorrect sensor readings. The
table has the value 0 in cells corresponding to decel (RPM above idle and
closed throttle) where reversion effects are most pronounced. BLM update,
but not closed loop feedback, is disabled in any BLM cells with value 1.
This means that the system always starts with 100% fuel in these cells. In
this table, the value 1 is used in the range of 750 to 1,500 RPM and 0% to
5% throttle position (TPS) to compensate for the unstable cold start
characteristics of a particular engine combination that includes an
aftermarket throttle body. Please refer to the TCFI Idle Tuning Tech Note
for more information on this subject (basic operation of the VRFI is the
same as our Twin-Cam TCFI system).
BLM Table Showing Special Values
What is the advantage of the new
VRFI system with dual channel WEGO?
The new system with front and
rear wide-band exhaust gas oxygen sensors allows a substantial reduction in
tuning effort compared to our earlier single sensor units. The tedious
operation of moving the single sensor from cylinder to cylinder during the
tuning process is completely eliminated. Auto-tuning is also extended into the
idle RPM range, further reducing the tuning effort. The new system is also
more tolerant of throttle body and throttle position sensor variations. Closed
loop operation occurs within 30 seconds even if the engine is cold.
For what applications do you
recommend the VRFI?
The VRFI is intended for high
performance race engines. Please note that the VRFI controller cannot be used
as a replacement for a failed Delphi®
How long does it take to
install and tune the VRFI for a typical application?
The VRFI is a simple plug-in
that will take about 10-15 minutes to install. You can expect to spend about 3-4
hours installing the WEGO as this requires exhaust removal and welding of
mounting nuts for the oxygen sensor. Initial tuning of the VRFI will
probably take 2-3 hours, with another hour spent doing final checks after
the customer has logged some time on the system. If you are doing
your first installation, you should plan on spending several days
familiarizing yourself with the system. If you encounter problems with an
aftermarket performance items, substantial
additional time may be required to complete the installation.
What skills and resources do I need to
successfully install and tune this system?
You need to make a realistic
assessment of your skill level. We have encountered issues with customers
that simply lacked the requisite PC literacy and resources to be successful
with the VRFI. If you have never worked with H-D®
EFI systems, the VRFI is not the place to start. Tuning the VRFI
requires competency in PC operation, using Microsoft Windows based
programs, and basic engine tuning and fuel injection mapping concepts
including the use of an exhaust gas analyzer to monitor AFR (air/fuel
ratio). The VRFI installer is assumed to be familiar with the Delphi®
fuel injection system and to have access to basic test equipment and
factory service manuals. We suggest that you download the
Installation and Tuning Manual,
study it, and make sure you feel comfortable with it before purchasing the
Our tech support is limited
to VRFI and engine tuning issues. We cannot provide tech support for PC or
Windows related issues. Please do not ask us to explain how to use a mouse,
open/close files, copy files to disk, organize folders, or other basic
Windows or PC operations. From a practical standpoint, you will require
broadband Internet access to download software and firmware updates and an
email account to send us files for tech support purposes. You will also
require a program such as PKZIP or WinZIP to archive files prior to
attaching to an email.
What level of tech support does
Daytona Twin Tec offer?
We have staff available to take
tech support calls during normal business hours. If an initial telephone
conversation cannot resolve the issue, we will ask you to email us the current
setup file and a data logging file exhibiting the problem. We will try to get
you a solution within 24 hours.
Please do not ask us to read
you the instruction manual, lead you through basic PC or Windows operations,
explain general engine tuning principles, or fax you pages from H-D®
service manuals. We do offer an extensive
FAQ on engine
tuning principles and we will gladly offer advice on specific tuning
Most tech support calls involve
tuning issues that can easily be resolved. A small percentage of applications
have underlying mechanical or parts compatibility issues that cannot be
resolved by tuning alone. The most common issues encountered include
mechanical/thermal problems with aftermarket or modified throttle bodies,
inappropriate exhaust systems, and inadequate starting systems for high
We do not offer any
installation, tuning or diagnostic
services at our facility. We do offer a free VRFI training course at our
facility and conduct seminars at major trade shows (please call for scheduling
details). We also offer a
FAQ on diagnostic
tools and suppliers.
What is the difference between
the VRFI and TCFI?
The two systems are very
similar. If you have used one of our TCFI systems, you will quickly become
very familiar with the VRFI. All the basic functions of the two units and
the accompanying software are the same, except that the VRFI has slightly
different electronics and firmware to support the unique characteristics of
the VRSC engine.
You cannot swap the two units
or reprogram the firmware to change a TCFI to VRFI or vice versa.
What is the difference between
speed-density and alpha-N fuel injection control systems?
The OE Delphi®
system is a speed-density control system. It remains a speed-density control
system even when devices such as the RevTech DFO, Dynojet Power Commander,
or Screaming Eagle EFI Tuner are added. The VRFI is an alpha-N control
calculates air flow (and consequently meters the correct amount of fuel to
attain the desired air/fuel ratio) based on engine RPM (the speed term) and
manifold pressure and temperature (the air density term). Once calibrated,
speed-density systems can accurately meter fuel as long as the manifold
pressure is well behaved. Speed-density system are somewhat forgiving
for minor vacuum leaks and inconsistent throttle body behavior. However,
speed-density control cannot cope with the erratic manifold pressure
characteristic of long duration, high overlap camshafts.
Alpha-N systems are typically
used in racing applications where the camshaft characteristics preclude
speed-density control. Alpha-N control calculates airflow based on throttle
angle (the alpha term) and engine RPM (the N term). In addition, most
alpha-N systems make a correction based on air temperature. The accuracy of
an alpha-N system is highly dependent on consistent throttle body behavior
and is adversely affected by any vacuum leaks. Adding closed loop feedback
from a wideband exhaust gas oxygen sensor greatly improves the accuracy of
an alpha-N system. The major advantage is that alpha-N control has no
dependence on manifold pressure and is able to tolerate radical camshaft
Do I need a load control dyno
with exhaust sniffer?
Regardless of what some
people may claim, it is impossible to properly tune a fuel injection system
on a modified engine without some means of covering the entire engine load
range (from decel to wide open throttle) and exhaust gas analysis. If you
use a system like the Dynojet Power Commander IIIr, you had better find a
shop with the DynoJet Model 250 load control dyno and optional air/fuel
You can accomplish the same
result with the VRFI and WEGO by simply riding the bike for several hours. As you run through different engine loads and RPM levels,
the system auto-tunes the fuel tables.
How do I set up and tune the VRFI
for a particular application?
We provide setup files for
common applications based on using the WEGO for auto-tuning fuel tables.
Some tweaking of idle fuel and ignition advance is generally required. We
suggest that you download the
Installation and Tuning Manual for more details.
Do I need to spend time on a
Auto-tuning under actual
riding conditions with the WEGO generally gives better results because the
operating conditions are more realistic. Do the auto-tuning first. Then, if
you want to get maximum horsepower at wide open throttle, do dyno runs to
fine tune the ignition advance and air/fuel ratio.
Will the exhaust system affect
From what we can see, this is
not going to be a major issue with the V-RodTM. The exhaust systems being
marketed for V-RodTM applications do not appear to suffer from the same type
of problems associated with exhausts for Twin Cam applications where many
products have been designed without any consideration of
gas flow dynamics.
Please note that if you use drag
pipes or other open pipes, auto-tuning may not be possible at idle or part
throttle due to reversion effects. Fuel tables for idle and part throttle
cells will have to be tuned manually.
If the WEGO is used for
auto-tuning fuel tables, should it be left hooked up?
Yes! Due to the inherent
limitations of sensing airflow by measuring throttle angle, Alpha-N fuel
injection systems cannot precisely control air/fuel ratio without feedback
from a wide-band sensor system. The VRFI is not intended to be used without
Can I use the VRFI on a custom
You must retain all the original equipment
sensors and actuators. Two areas that are often overlooked are the
instrument cluster and turn signals. Like the stock Delphi®
ECU, the VRFI requires a vehicle speed sensor (VSS) signal. If you are using an aftermarket instrument cluster, you can connect the VSS
sensor directly to the VRFI. With the VRFI, you can eliminate the stock turn
signal/security module (TSM/TSSM) and use any aftermarket turn signal
controller. The VRFI also
has an output that will drive a conventional aftermarket tachometer.