General Tuning Info for Beginners

[Jim Wilson]

I'd like to start out with a big thanks to Damn Yankee and Chris for making this tuning section happen!!!

I'd like to share a link that helped me to understand the whole tuning process. I have a blower on my Tacoma and my buddy Steve (Gadget) put this document together to help us Toyota owners tune his supercharger upgrade kit. Yes I know...it's blaspheme to have anything related to a Toyota on a VIPER forum, but the theory is the same. I had to read it....read it again, then read it one more time for it to begin to make sense.

http://www.splitsec.com/tuneguide.htm

Here is another liink that has a wealth of information.......

http://www.innovatemotorsports.com/resources.php

I'm sure there are others out there, but these are the only ones I'm familiar with. Hope they are helpful.

 

[DAMN YANKEE]

Great links!

Here is what I developed, I found it worked for me very well...​

Glossary of Terms​

AF, A/F Air to Fuel = The ratio of mixture of fuel to air. See “Lamda”.

Adaptives = The means to properly address and adjust stock PCM operation through the use of the “in series” VEC3 system. Adaptives is a broad and somewhat general term referring to both the ability of the 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.”

Detonation = 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 hugeincrease in unburned hydrocarbon (HC) emissions. This can cause rough idle, hard starting and stalling, and may damage the catalytic converter . Lean mixtures also increase the risk of spark knock (detonation) when the engine is under load.

Duty Cycle = Refers to how long an injector is pulsed relative to the amount of time available (based on the position of the valves). If one needs to inject more fuel than time allows, one will need “larger” injectors (higher volume) to deliver greater amounts of fuel in less time. Generally there is 20ms of injector pulse time available at 6,000 rpm.


Engine Load = Measurement of how hard an engine is working. The higher the load the harder the engine is working. Heavy loads (WOT) provides for the transition between Closed Loop and Open Loop operations.

Forced Induction Engines = Forced induction is a term used to describe internal combustion engines that are not naturally aspirated. Instead, a gas compressor is added to the air intake, thereby increasing the quantity of oxygen available for combustion. This compressed air is normally referred to as Boost or charge air. A Supercharged engine is a good example of forced induction.

FTDI USB Driver = Software program required to allow the VEC3 to be recognized and interfaced with your laptop or 3rd party card reader/writer.

Fuel Injector Drivers = The VEC’s ability to recalibrate the ignition timing and fuel curves in conjunction with the stock PCM.

Fuel Rail = A component of the fuel system that provides pressurized fuel to the injectors. Modified engines may require higher volumes of fuel to be delivered to larger injectors, hence Fuel Rails may be upgraded to a larger capacity components.


IAC = Idle Air Control motor.

IAT Intake Air Temperature = One of many parameters required to properly derive the correct fuel to air ratio. The VEC3 has no internal air temperature sensor, rather it uses the offset of the stock PCM to compensate for temperature.

Ignition Timing = The timing of ignition relative to the position of the piston in an internal-combustion engine.

Injectors, FI = Fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure to add fuel to the air stream entering the combustion chamber.
Injector Pulse Duration The PCM provides for the duration of time in which the fuel injectors are pulsed or “open.” Setting up for the proper use of standard or larger fuel injectors, administering their required pulsing while accounting for all the additional parameters are done through the PCM and VEC3.

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.
LTFT Long Term Fuel Trim. See below.

Long-Term Fuel Trim = Adaptives When setting up the VEC3 to provide tuning capabilities, the first requirement is to determine what long-term fuel adaptives are being employed by the stock PCM. These long-term adaptive values are first set as close to “zero” at idle as possible through the use of a scan tool and the VEC3.

MS, Milliseconds = One thousands of a second.

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 .

MPS Manifold Absolute Pressure = Sensor used to transforming the load signal into an electrical response that the ECU uses to determine the appropriate injector pulse duration among other operations.

OBD2 = OnBoard Diognostics A diagnostic device plugged into a cars ODB2 port providing a set of diagnostic data by reading and allowing reaction to “trouble codes”

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.

Oxygen Sensors = See “WB, WBO, Wideband”

PCM = Pulse Code Modulator, a term referring to the stock factory “on board” engine monitor/computer.

Pull = Creating the conditions required for “Closed Loop”, hard acceleration, full throttle or boost. Used for logging to review data and tune the engine.

PWM Pulse Width Modulation = A selectable, user configured output of VEC3 used to activate a relay or switched device like a “shift light” or Nitrous system.

RPM Revolutions Pre Minute = A unit of frequency, commonly used to measure rotational speed, particular in the case of rotation around a fixed axis. It represents the number of full rotations of the crankshaft within one minute.

SC = Supercharger

Smart Card = Computer storage media. A credit card sized media used to transfer data to the VEC3 system. VEC3 can also write to these cards, storing programs for future reference and/or use.

Spark Advance = The timing of ignition relative to the position of the piston in an internal combustion engine.

Spark Knock = See “Detonation”

Stoichiometric air/fuel ratio = 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 the Greek letter "lambda."

Throttle Position = The relative position of “openness” of the throttle body, the higher the position the more air is being delivered to the intakes.


WB, WBO, Wideband = High performance oxygen sensors used to monitor the level of unburned oxygen in the exhaust. The amount of oxygen that's left in the exhaust following combustion is a good indicator of the relative richness or leanness of the fuel mixture. These are usually placed in the collector of the exhaust manifold, prior to the Catalytic converter. See ”lamda”

W/M = Water/Methanol injection.

WOT = Wide Open Throttle, the highest/hardest acceleration. See “Load.”