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Big Stuff 3 Transient Tuning Combined MAP/TPS methodology

Practical Standalone Tuning

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Discussion and questions related to the course Practical Standalone Tuning

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I apologize up front for the long post. I have watched all of the transient webinars and the all of the practical tuning lessons. Everything in the Big Stuff 3 I have tuned before with no major issues but the transient just confuses me. Watching the HPA videos has definitely makes more sense if I was using those ECU and is more a purely TPS bases tuning.

This is where/why my confusion sets in. Big Stuff has 7 Transient tables 5 MAP based and 2 TPS base. For the MAP it has all of the normally rate of change, rpm adjustments, increase/decrease rate. The TPS only has rate of change and rpm modifier. All maps are 2d both MAP/TPS.

My thoughts if I only tune using the TPS settings is this. On my turbo car, once I stab the throttle and all of the asynchronous fuel is use but my MAP keeps increasing that I am out of transient fueling. In the long run, I will need to tune the MAP transient maps as well. Since they impact each other, should I just tune the map or what should my approach/steps be to ensure I am not over loading or over thinking this.

I greatly appreciate any and all help that is provided. I have included pictures and a descriptions of the each table for reference.

Power Valve (dMAPdt rate of change)

It is used to determine the percent fuel correction, either positive or negative, for a change in manifold pressure (dMAPdt). The ECU calculates the change in manifold pressure every 52 milliseconds (ms) as long as the throttle is moving. The ECU will increase or decrease the base pulse width relative to the dMAP Correction table’s % correction value (i.e. 100%).


dMAP RPM Modifier

Inputs to the table are used to increase or decrease the dMAP correction as a function of engine RPM. The positive or negative value inputted into the table is the percent (%) applied to the dMAP Correction table relative to the RPM.

MAP Accel Enrich Decay Rate

It is used to determine how quickly to decrease the Positive dMAP correction value after accelerating (throttle tip-in) the engine at a given coolant temperature.

MAP Accel Enrich Increase Rate

It is used to determine how quickly to increase the Negative dMAP correction value after decelerating (throttle tip-out) the engine at a given coolant temperature.

Run time Correction

. It only influences the Positive dMAP and dTPS Correction Values for a short period of time after the engine is running. (i.e. up to 8 minutes). The amount of Run Time Correction fuel is decreased as time transpires and the engine warms up. The first cell in the table, all the way to the left, represents the first ½ minute of engine run time. The cell all the way to the right represents the end or eighth minute of engine run time. The Run Time Correction table’s input values need to decrease as you work from the left to right.

TPS Accel Pump Shot

The ECU uses the Accel Pump Shot table value to compute the size of the Asynchronous Pulse Width (APW) for a given rate of throttle change. It does so by sensing the rate of the throttle change and then using the corresponding Accel Pump Shot table value to calculate the size of the asynchronous pulse width.

TPS AE position Correction

The ECU uses the AE Position Correction table value to modify the size of the Asynchronous Pulse Width (APW) relative to the throttle position at which the dTPSdt event occurred.

Attached Files

Hello, not a ECU I'm familiar with, I'm taking it you have read through the manual many times http://bigstuff3.com/pdf/GEN3%20User%20Manual%20-%20Feb%202011%20-%20Rev%202.2.pdf from page 80 onwards, it is very intense and lot of information to take in i think i would be starting with removing all accel fuel and then increasing the tps and asynchronous leaving the decel side alone first and data logging and data logging and more data logging before approaching the map-based side

Regards Ross

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