Originally Posted by
ayousef
Well what you're doing sounds right for WOT tuning and to make sure it isn't limiting, however on a Forced Induction application, part throttle drivability suffers and will cause throttle surges unless you lower Driver Demand significantly, after which you have almost no throttle response left and would require 30% pedal just to keep the car at a steady speed etc...
Whats happening is the following:
youre driving in 3rd gear at 2500rpms and requesting (Driver demand) 40KW of power. At this RPM that equates to 150nm of torque, however Max Engine Torque is at 250nm, everything is fine. Now as soon as the car shifts into 4th gear and revs drop to 1250rpms (while you are maintaining the same pedal position) meaning you are still requesting 40KW but at 1250rpms that equates to 305nm while Max Engine Torque is at 200nm. The fact that you are requesting MORE than what the ECU thinks the max engine torque is causes it to swing the throttlebody open to "meet" the requested torque only to be hit with a big surge in power, overshooting the requested torque and then brought down via the intergral and proportional torque controls to where they should be.
The same thing happens anytime a sudden change in throttle position causes a large sudden rise in driver demand torque, approaching or exceeding Max Engine Torque.
The only way around this problem is to lower driver demand so it doesn't approach or overshoot the Max Engine Torque values which sucks, or find a way to INCREASE Max Engine Torque WITHOUT consequently increasing delivered torque.
In this case if my supercharged truck gives me a Max Engine Torque value of 300nm at 2000rpms and a high TPS, then I want to be able to change it to say 700nm without altering anything else.
Editing the Airmass torque tables unfortunately increases Max Engine Torque but also increases delivered torque (hence the reason why shifts become firmer).