This something I found on forum B this morning
Quote:
"From Hector:
"I took your BD TSB questions to our engineers. Here is what they have come back to me for you all":
Background – Torque Management:
Torque management is solely an artifact of the programming within the powertrain control module. Manufactures program newer vehicles to reduce the allowable torque output for a number of reasons including but not limited to reduced driveline shock, reduced strain on the transmission and reduced engine exhaust emissions. This aids both reducing the manufacturer’s warranty costs as well as increasing engine peak output while not exceeding the torque limits of the transmission and driveline components in the lower gears. This has become increasingly important as vehicle manufacturers continue to complete in the horsepower and torque figure arena. This torque reduction occurs during a plethora of conditions including if the vehicle is stationary, the transmission is currently changing gears, if the vehicle is in top gear, if the engine temperature exceeds safe limits and many other reasons.
With sufficient technological capabilities, a powertrain control module may be modified by altering the calibration tables that are referenced in the operating system programming. This process is usually referred to a tuning or altering the calibration. It is then theoretically possible to reduce the torque management or eliminate it entirely. This is very rarely done fully or correctly as there are many factors at play, for example the transmission control strategy may signal the engine controller to reduce torque, which leads to tuning both modules or completely rewriting the operating system of the engine controller; there are so many torque management tables in modern vehicle computers it is often not possible to map all of them out. For this reason control module tuning or recalibrations often do not correctly increase the desired torque and the torque management tables in the controller but instead simply increase injector duration to simulate this effect, often in conjunction with some torque management changes. This is why some will still find improvements with an add on like the BD Throttle Sensitivity Booster even with a tune.
BD Throttle Sensitivity Booster:
This product connects to the accelerator pedal position sensor (APPS) also known as the throttle position sensor. The BD module then alters the signals from the accelerator pedal to the powertrain control module. The powertrain controller uses these signals to look up the desired torque that the driver is demanding and de-rates it according to its torque management program. The BD module manipulates the torque demand signals so that they ramp up faster than normal. This means that although the torque management is still enabled and still limiting power output to the same level, the driver is able to realize all the torque the powertrain control module will allow, rather than a portion of it as may be the case with a slower responding torque demand signal input.
At the end of the day, the BD Throttle Sensitivity Booster will help get you up on power quicker but does not eliminate torque management and does not increase total power. Thus it is warranty safe and will not alter your vehicles exhaust emissions – something that no aftermarket tune or recalibration can provide.
Regarding fuel rail modifications:
We have no empirical data to support physical modifications to the fuel system on a late model Cummins engine will in any way reduce the apparent lack of acceleration or torque management experienced. If anything, it may be a detriment as there is an increased risk of foreign material ingress, and the feedback control of the powertrain controller may be jeopardized, leading to less consistent fuel rail pressures.
The fuel system is a high pressure direct injection common rail setup. It uses closed loop PID control over injection pressure to ensure that regardless of the size of the restrictions in the fuelsystem, the high pressure pump output will compensate and maintain fuel rail pressure. Additionally, if the fuel rail pressure does deviate up or down from the desired level this does not mean the engine will receive more or less than the correct amount of fuel. The program in the controller is to adjust fuel injection duration to increase duration if rail pressure decreases to ensure consistent quantity delivery.
From our testing, we have seen lags in fuel pressure response during tip-in on modified vehicles with very large fuel demands due to large injectors and increased injection duration. However, the quantity of fuel required at initial take off is very minimal when compared to wide open throttle operation where the engine may be operating at a pressure ratio of 2:1 rather than 1:1, high engine speed and the increased allowable torque fuel demand may be eight times higher. We have on the other hand noted improvements in this transient area with using higher output high pressure fuelpumps but this is not a requirement on a stock vehicle.
Hector McLean
BD Diesel Performance
Sales & Tech Rep.
1-800-887-5030
heck@bd-power.com
BD Power - The Leaders in Diesel Performance"
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