VRFI Fuel Injection

Why is the VRFI auto-tuning capability superior to competitive products?

Competitive systems such as the ThunderMax and the new Dynojet Power Vision claim to have auto-tuning capability. Prospective customers should ask whether a given system meets two important criteria:

1. Is 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 auto-tuning corrections? Any "feedback" system using a sensor to make corrections is subject to operating regions where instabilities or errors exist.

The Thundermax 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 BLM tables.

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 module. 

 

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 VRFI Installation and Tuning Manual, study it, and make sure you feel comfortable with it before purchasing the VRFI system.

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 Tech FAQ on engine tuning principles and we will gladly offer advice on specific tuning issues.    

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 compression engines.   

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 Tech 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 system. 

Speed-density 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 profiles. 

 

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 ratio monitor. 

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 VRFI Installation and Tuning Manual for more details.

 

Do I need to spend time on a dyno? 

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 the VRFI?

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 the WEGO. 

 

Can I use the VRFI on a custom motorcycle?

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.