Hey guys...
First, you first calling Sean was the right way to go. It is very unusual that he didn't get right back to you. Here is his cell phone number, call him at a decent hour as the guy works very hard 904-535-4949.
First we start with terms for those that do not know them:
http://forums.viperclub.org/rt-10-gts-discussions/600255-glossary-terms-induction-engines-tuning.html
PCM to makes automated adjustments to the motor by the reading sensors and applying programmatic tuning (injector offsets as example) and, in regard to the VEC3, the ability of the VEC3 to apply more appropriate tuning in Open Loop operations.
Bar pressure sensor (BPS) Description of pressure, the VEC3 has an internal Bar Pressure Sensor that can read 30” Hg vacuum to 22 PSI boost pressure within the manifold. This provides additional data required top properly configure the adaptives interfacing with the stock PCM.
Boost See “Forced Induction Engines.” Compressed air, above what is considered “normally aspirated”, measured in pounds of pressure delivered to the intake manifold.
Closed Loop A term whereby the stock PCM is monitoring the oxygen sensors and making constant changes to the injector pulse to keep the air / fuel ratio in the factory programmed range. This is a low load condition, one in which the stock PCM has the ability to make adaptive changes automatically. See “Open Loop.”
Compression Ratio The ratio between the volume of a combustion chamber and cylinder, when the piston is at the bottom of its stroke and the volume when the piston is at the top of its stroke. The higher the compression ratio, the more mechanical energy an engine can squeeze from its air-fuel mixture. Literally, high ratios compress increased oxygen and fuel molecules into a reduced space, allowing for increased power at the moment of ignition. Higher compression ratios, however, also make detonation more likely. See “Detonation.”
Lamda = When air and gasoline are mixed together and ignited, the chemical reaction requires a certain amount of air to completely burn all of the fuel. The exact amount is 14.7 lbs of air for every pound of fuel. This is called the "stoichiometric" air/fuel ratio. It's also referred to the Greek letter "lambda." When lambda equals one, you have a 14.7:1 stoichiometric air/fuel ratio and ideal combustion. When the air/fuel ratio is greater than 14.7:1, lambda also will be greater than one and the engine will have a lean mixture. Having stated that, it is important to note that, under load, a normally aspirated motor may perform best at 12.9:1, while a forced induction motor may perform best anywhere from 11.5:1 to 12.5:1 depending on air temperature and other variables.
Lean mixtures improve fuel economy but also cause a sharp rise in oxides of nitrogen (NOX). If the mixture goes too lean, it may not ignite at all causing "lean misfire" and a huge increase in unburned hydrocarbon (HC) emissions. This can cause rough idle, hard starting and stalling, and may even damage the catalytic converter. Lean mixtures also increase the risk of spark knock (detonation) when the engine is under load.
When the air/fuel ratio is less than 14.7:1, lambda also is less than one and the engine has a rich fuel mixture. A rich fuel mixture is necessary when a cold engine is first started, and additional fuel is needed when the engine is under load. But rich mixtures cause a sharp increase in carbon monoxide (CO) emissions, generating more heat at the catalytic converter with resulting damage.
When the relative proportions of air and fuel are "just right," the mixture burns clearly and produces the fewest emissions. The trick is balancing the mixture as driving conditions, temperatures and loads are constantly changing.
Log, logging = Graphical and numerical visualization and verification of numerous performance monitoring sensors. Captured for a discrete period of time and displayed in a variety of manners, a log provides the user with concrete indications of current engine performance and tune. Form the data represented in the log, one can tune the engine to achieve a different performance outcome.
Manifold Pressure = The pressure in the intake manifold of an internal combustion engine. See MAP.
Manifold Vacuum = Engine intake vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere.
MAP, MP = Manifold Absolute Pressure Directly related to engine load, and used to help determine the Air to Fuel ratio and the appropriate timing for the ignition of the cylinder
Open Loop = A full throttle condition where the stock PCM switches out of “closed loop” operations. In open loop the stock PCM ignores input from the oxygen sensors and the normal adaptives are locked-out and pre-set curves come into effect.
VEC = Viper Engine Controller, a Roe Racing product that actively assists the Viper's own PCM in providing proper tuning.
PCM = Pulse Code Modulator, a term referring to the stock factory “on board” engine monitor/computer.
Throttle Position = The relative position of “openness” of the throttle body, the higher the position the more air is being delivered to the intakes.
WOT = Wide Open Throttle, the highest/hardest acceleration. See “Engine Load.”
The issue of the PCM throwing a "low signal" code when you go WOT. I am with Viper Tony on this one, you either damaged the MAP wire and are getting a diminished signal, have a bad MAP sensor (smaller chance of that) or have miswired the rig, In any event, its all an easy fix. And there Viper Tony is giving great advice as well. You should log the signals of BOTH the Vipers own MAP sensor (external VEC setting) against the VEC's own MAP sensor (internal setting). By looking at the two signals logged out you;ll be able to see if the stock MAP sensor is generating any signal and if it is, if it close to the VEC's own.
The issue of whether you can run the Viper by just using the VEC's own internal MAP signal. Yes, I use the VEC's internal MAP sensor for all my work and you can to. I would still completely resolve the stock MAP issues though.
The issue as to when the MAP sensor is actually used...in Closed Loop...Open Loop or both. In Closed Loop (90% of all of our driving) the PCM relies heavily on all of the sensors. The output of the MAP sensor is used in conjunction with intake manifold air temperature, throttle position, RPM, O2 sensors, etc., etc. as well as various other static tables to determine the amount of incoming combustion air and consequently the amount of fuel to be metered to get the rig close to LAMBDA. Now in Open Loop, the engine switches off these interactive tables and goes to a hard map. That map is set based on the tuning work that you will do based on your logs. So...in Open Loop the MAP sensor is not used but the VEC is still hard at work, haivng been instrumental at resetting the hard maps taking into account all the substantial modifications you have made that the stock PCM just does not have premapped.
