Calibrator Description:
The VEC1 Viper Engine Calibrator provides adjustment of the air/fuel ratio and ignition timing over the entire operating range of the engine. Furthermore, these adjustments can be made by the driver "on the fly" to optimize settings for the current driving situation. It is especially useful for recalibration of cars with modified engines, intake or exhaust systems.
Calibrator Features:
- Low load calibration
- High load calibration
- Output clamp (assures output is kept within PCM parameters)
- Filter to provide smooth idle and reduce noise
- Transient surge and battery reversal protection
Air/fuel Ratio Gauge Description:
The air/fuel ratio gauge is a precision, miniature instrument that provides an easy to read, real time indication of the air/fuel ratio. The gauge has a 10 segment, 5 color LED display. The use of color makes the gauge readable with peripheral vision. It is calibrated for a 1V full scale input range and a sensitivity of .1V per display segment.
Air/fuel Ratio Gauge Features:
- 5 color display is easily read
- Dimming feature automatically reduces display brightness at night
- Signal filtering enhances readability of the display
- High input impedance does not effect operation of the exhaust oxygen sensor
- Battery reversal protection
How To Interpret The Air/Fuel Display:
The segment illuminated indicates the instantaneous air/fuel ratio of the engine. Exhaust gas oxygen sensors must be up to their normal operating temperature before they produce valid readings. After the engine runs for a few minutes, its hot exhaust gas will appropriately elevate the temperature of the sensor.
The yellow LED's on the gauge indicate a near stoichiometric condition. At this operating point, the engine is mixing the proper ratio of air and fuel for complete combustion. The engine will have good fuel economy and minimum exhaust emissions.
When a green segment is illuminated, the engine is running in a rich condition. A rich air/fuel ratio is associated with a value less than 14.7:1. Rich operation corresponds to higher power output, lower fuel economy and higher emissions of carbon monoxide and hydrocarbons.
Blue segments indicate a very rich condition. A very rich mixture should only occur under hard acceleration.
Orange LED's indicate a lean condition. Lean operation is associated with improved fuel economy and higher emissions of oxides of nitrogen. Lean operation is suited for light load cruise and coast down conditions.
Red segments indicate a very lean condition. Very lean operation must be avoided when the engine is under load. Such operation results in fuel starvation and can lead to engine damage.
In closed loop operation, the PCM continuously adjusts the air/fuel ratio. As a result, the display will cycle above and below the stoichiometric point quickly as the computer makes adjustments.
Typical Display Characteristics:
LED Color Min (V) Max (V) A/F RATIO
1 RED 0 0.1 17.0: 1
2 RED 0.1 0.2 16.0: 1
3 ORANGE 0.2 0.3 15.5: 1
4 ORANGE 0.3 0.4 15.0: 1
5 YELLOW 0.4 0.5 14.7: 1
6 YELLOW 0.5 0.6 14.6: 1
7 GREEN 0.6 0.7 14.5: 1
8 GREEN 0.7 0.8 14.2: 1
9 BLUE 0.8 0.9 13.2: 1
10 BLUE 0.9 1.0 12.5: 1
Front Panel Adjustments:
Low:
This dial is called low because the changes made with it cause a much greater percentage change at low engine loads. Low engine loads are idle, steady low RPM cruising and light throttle changes (less than half). Adjustments made with it affect the low load calibration of the PCM.
High:
This dial is called high because it is the primary way to adjust at high loads. High loads occur at heavy and full throttle acceleration. Adjustments made with it affect the high load calibration of the PCM.
Adjustment Procedure:
Begin with the controls set to the zero position. At these settings, the PCM spark and fuel curves are at original factory specifications.
Adjustments made with the VEC1 will affect the air/fuel ratio and ignition spark timing together. Turning the low and high dials to negative settings increase spark advance and decrease fuel. Positive settings richen the fuel mixture and reduce spark advance.
In our testing, the original calibration from the factory has shown to provide excessive timing advance and too little fuel at light loads. Under heavy loads, the engines are running excessively rich and have too little timing advance. The VEC1 will allow you to alter these conditions to improve throttle response and increase power.
Begin by adjusting the low control for improved throttle response at light load changes. While driving the car at a steady 45 MPH in 4th gear, accelerate briskly up to about 55 MPH. Adjust the low to a positive (+) setting, 2 positions at a time, getting a feel for the throttle response after each change. When you have found the throttle response to have improved in all but your last adjustment, back the dial off 1 position and retest. Cars with stock cams usually end up in a range of plus (+) 12 to 16 on their low settings for increased throttle response and driveability. Engines with forced induction or higher lift / duration cams usually need negative settings in the (-) 4 to 8 range to improve idle and eliminate service engine codes.
Once the low has been set, begin adjusting the high setting for improved power at heavy loads. In a suitable location, accelerate full throttle and note the air/fuel ratio. Begin adjusting the high control dial to a negative (-) setting, 2 positions at a time, watching the air/fuel ratio each time. Generally, the correct setting is found when the air/fuel ratio gauge is illuminating the last green to first blue LED (14.2 to 13.2 :1) in upper RPM / full throttle conditions. If you make an adjustment and the air/fuel ratio gauge shows a leaner condition under hard acceleration, abort the run and turn the high toward the positive (+) at least one position and retest. At this point the spark advance has increased by approximately 6 to 7 degrees and we have reduced the excessively rich fuel mixture. High settings on cars with stock cams usually range from negative (-) 12 to 16 for increased horsepower. Engines with forced induction or higher lift / duration cams usually need positive settings in the (+) 2 to 6 range to improve power and torque.
The low and high controls are somewhat interactive. Which may make it necessary to repeat the adjustment of the controls. Once set properly, adjustment of the high control by itself will affect the entire operating range.
To get the most out of your VEC1's tuning capabilities, we recommend the use of equipment enabling you to link to the PCM and also monitor the ignition spark advance. The VEC1's adjustment range is wide enough to cover many different engine modifications. The user is responsible for his own actions and adjustments. The VEC1 is intended for off-highway use by qualified individuals.
Battery Replacement:
If you replace the battery in your car, set the VEC1 back to 0 / 0 before starting the engine. While driving, return the low and high settings to their previously set values.
