I found my CD with some of the highlights of the VEC. It is pasted below. I don't if this means it uses the factory tables or not.
Roe Racing USA
VEC3 System and Software Operating Instructions
Ver.3.6.11
Features & Benefits:
· Manifold pressure and RPM referenced fuel calibration.
· Manifold pressure and RPM referenced ignition timing calibration.
· Internal 2.5 bar pressure sensor.
· Analog input from external 0-5V sensors (allows utilization of stock sensors for reference input).
· Analog output voltage limit functions (useful on forced induction using stock MAP sensor or controlling oxygen sensor voltage).
· Allows for the use of significantly larger fuel injectors while retaining proper air / fuel ratios.
· Individual cylinder fuel trim.
· Intake air temperature referenced fuel offset.
· Internal injector drivers operate high resistance fuel injectors, while using external resistors will allow the VEC3 to run low resistance injectors.
· Smart Card programmable. No need to link to VEC3 to make program changes.
· Allows for stock-like drivability on heavily modified engines.
· Programmable RPM limit (must e at or below stock setting).
· Utilizes factory PCM adaptive capability to properly adjust for various operating conditions, such as altitude, engine coolant temperatures, etc.
· Programmable output signal (ground) can be used to activate a switched component or PWM (pulse width modulation) controlled component.
· Does not alter other stock PCM functions, allowing for full OBD2 functionality.
· Full data logging system with graphing screen.
· 3D mapping view of VEC3 fuel and ignition programs.
· Active fuel and ignition cells are highlighted in the VEC3 software while linked to the system in the logging mode.
System Overview:
The VEC3 Viper Engine Calibrator allows precise tuning of the air to fuel ratio and ignition timing over the entire operating range of the engine. Simply inserting a pre-programmed Smart Card immediately changes the program settings for the current driving situation or octane of fuel as desired.
The unit contains its own fuel injector drivers and is wired in between the factory PCM and engine. It is especially useful for recalibration of both forced induction engines and those with extensive modifications, allowing the tuner to quickly get the engine running correctly. Stock engines can also benefit greatly from improving the ignition timing and fuel curves.
The VEC3 is similar to a stand-alone engine management system, but also has similarities to a piggyback system. We consider it as working “in series†with the factory PCM.
In a true stand-alone system, you must program for every operating condition the engine will experience, such as load, throttle position, RPM, engine temperature, air temperature, etc. These systems can be quite complex to tune. Most PCM’s also control radiator fan operation, A/C operation, emissions operation and diagnostic functions. Stand-alones are generally not compatible with OBD2 emissions testing in that they replace the factory PCM and will not link up with state run emissions equipment. These systems are best suited for racetrack use where engine tuners can fine-tune the program to the environment of the moment for optimal performance.
In a typical piggyback system, control over the engine is done by manipulating inputs to the stock PCM. Manifold air pressure and oxygen sensor voltages can be altered in order to make the PCM change its load calibration, thus altering fuel and ignition advance curves. Reducing MAP sensor voltage has the effect of reducing injector pulse width by making the PCM “think†the engine is under greater vacuum than actual. At the same time, ignition timing is advanced due to the PCM believing the engine is under a lower load. Conversely, increasing voltage has the opposite effect, increasing fuel and reducing timing advance. When tuning with systems of this type, you can find yourself in situations where you can have proper part throttle tuning, or proper full throttle tuning, but rarely both if the engine is heavily modified or has forced induction.
The VEC3 offers the best of both worlds. Stand alone system control, but with the simplicity of a piggyback system. The VEC3 controls fuel and timing, leaving the stock PCM to handle all other functions, such as idle speed, A/C control, emissions operation, etc.
System Function:
The VEC3 uses the factory PCM injector pulse output as a timing reference, which can be scaled within a range of 0% to 199%. This is beneficial in that if you’re using larger injectors, you can use a calculated percentage of the stock PCM pulse to make the larger injectors flow the same as the stock ones. This allows the engine to start up and immediately operate with the proper air/fuel ratio in closed loop operation. For use under a heavier load (full throttle / boost), you can create a fuel curve that begins adding milliseconds of injector pulse width as the load / boost increases. The fuel curve can be further adjusted based on the engine RPM, since the engine efficiency / fuel demand can change with RPM. Negative values can also be placed in load and RPM tables, allowing you to shut off injectors under deceleration and trim down fuel when it is otherwise too rich (both very beneficial for naturally aspirated engines). Fuel is finally trimmed by way of an intake air temperature correction factor if desired.
Ignition timing can be controlled within a range of 25 degrees advance to 25 degrees retard from the factory settings. The curve can be configured based on engine load and RPM. The factory PCM continues to drive the coils, though the input and resulting delivered spark advance is controlled by the VEC3. In places where the factory programmed timing curve was too advanced for an engine, such as under boost, it can be retarded, while leaving normal timing in vacuum conditions. You can also add timing advance in areas where the factory programmed timing advance was insufficient, such as for naturally aspirated engines.
The VEC3 has a programmable ground output wire. The output can be used to operate a relay, turn on a shift light, operate a PWM injector circuit, etc. The output is signal (manifold pressure or voltage) and engine RPM referenced. For example, you can create a program which will turn on a Nitrous relay, increase the injector pulse and decrease the ignition advance all at the same time.
For custom configured uses, the VEC3 has programmable analog output signal functions. This feature is primarily used to control sensor voltages sent to the stock PCM. One useful forced induction example would be sending the stock MAP sensor signal through the VEC3. A tuner can adjust the maximum allowable voltage that will go to the stock PCM, keeping check engine lights from occurring due to the PCM seeing a MAP sensor voltage higher than normal when under boost. An additional example would be found in use on 2003 and newer Viper engines, where control of the oxygen sensor voltage output is needed since the PCM’s hold closed loop for a short period of time at full throttle.
The different fuel and timing programs are written using the VEC3 software. Program files can be modified, saved, e-mailed and written to Smart Cards with serial and USB plug reader / writers. The VEC3 has an internal Smart Card reader and writer. To change the program, simply slide the card into the slot and wait for the green ready light to blink (typically 1-2 seconds). Using Smart Cards allows you to quickly change the program without having to link up to the VEC3. You can have an unlimited number of Smart Card programs (they are rewrite-able) and they are compact enough to put in your wallet.
The VEC3 can be linked to via a USB cable connection. From this connection, the VEC3 program can be read and modified. Additionally, the VEC3 is also a full-featured data logger (see separate logging instructions).
