RomRaider

There are several special functions and thresholds in the MS41 ECU that don't necessarily need a sub-group of their own so I have combined them into this one. I'll update this post as I define more of them.

Closed Throttle - Throttle Threshold
If throttle is less than this value, "Closed Throttle" mode is active.

Intercept - Engine Speed Threshold
If Engine Speed is less this value, allow "Intercept" mode to be active. The Intercept function is generally used in calculations to promote a smooth transition from a decelerating engine to an idling engine. It can be used to adjust Ignition Timing, Fueling, and Idle Speed Regulation.

Rapid Engine Speed Drop - Integral Additive
If "Rapid Engine Speed Drop" mode is active, the Integral component of the PID loop used to regulate Idle Speed is immediately increased without obeying any Integral limits to help prevent an undershoot when approaching the Idle Speed Target. This tables determines how much the Integral is increased if this function is active.

Rapid Engine Speed Drop - Engine Speed Gradient Threshold
If the throttle is closed, and Engine Speed is less than "Intercept - Engine Speed Threshold" and Engine Speed Gradient is less than this value, "Rapid Engine Speed Drop" mode is active.

Dashpot - Nominal
The Dashpot function acts like a throttle lever damper on a carbureted engine. It is used when closing the throttle to promote smooth torque reduction. It may need to be adjusted for large diameter throttle bodies because even a small change in throttle can result in a large percentage difference in airflow, especially at low throttle angles. The values in this table are immediately applied when they are increasing but are only allowed to decrease gradually using "Dashpot - Decay Limitation".

Dashpot - Decay Limitation
These values are used to soften the torque reduction when the throttle is closed. Smaller values result in a more gradual closure of the IACV and therefore a softer torque reduction.

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This has the potential to be extremely valuable for the LWFW guys. I never liked the idea of simply bumping the idle to trim out the idle drop. Having the ICV 'jump in' sooner on its way down would be perfect. I shall test, i have a UUC 8lb fw car here now.

Yes. Also play with the Derivative table from the ISR folder.

Good point, this might be good, I had to raise my RPM due to lighter weight flywheel (def not 8lbs though), but also it helped with the chatter, especially with AC on. My clutch is a ceramic multi puck clutch, which is probably the most annoying thing in the world (it's either on or off, hardly any feathering possible), so raising the idle RPM keeps me from potential stalls.

Hello

I mounted a m3 intake on my m52b28, I also switched to ethanol. since the assembly I have a problem that I can not solve, I have a hole in the acceleration with very lignt throttle under 2000rpm.

I tried everything in the map fuel, it does not change.

while doing research I found the dashpot, or it is explained that it is necessary to modify this map if one changes the throttle, because it influences the light throttle as it is explained.

but how to modify this map?

thank you

Don't think the dashpot function has nothing to do with that. The reason could just be the m3 itb setup which has just too big runners for stock m52 or close to stock. I have seen low rpm breathing broblems in many setups.

thanks for your answer, the engine is not stock stock, it also has cams shrick, line 2x60 stainless steel exhaust manifold

Hello

About "Dashpot - Nominal" values. Do smaller values result in a more gradual closure of the IACV?

Thanks

Added MS41.0 328i maps for comparing:

I'm going off memory but I believe larger values would result in a more gradual reduction of engine RPM.

SO if I understand this correctly, the dashpot values can be directly responsible for the rev hang (or even sometimes increase) when changing gear below 3500rpms?

This has been driving me nuts for a very long time and haven't been able to come up with a solid conclusion as to what causes it.

If M52B28 search for pazis post for rev hang delete at this .
Setup works well.
Rev hang is caused by for e.g. driving comfort. There is a document out there which descripe a lot about.

Possibly.

i have this issue in a 323ti 1998 with ms41.2
where is this post to delete the rev hang?

tks!