Alpha N
Posted: Sun May 29, 2011 9:24 am
Hi Jeroen,
I own a 320is e30 and i was registered in the old forum.
I spent a few years (actually weeks considering that i didn't work on it 24h a day
) in the study of the Motronic software, trying to adjust it via the Ostrich eprom emulator to make the engine running removing the stock AFM and replacing it with a potentiometer (standard alpha n setup).
I have also a wide band lambda sensor + gauge.
I partially succeeded: i only could achieve the same stock power, no significant gain in terms of torque or torque moving along in the rpm range.
As far as i know the main injection algorithm is IT=Q/(nxK) where IT is the Injection Timing, Q is the "airflow parameter" which is assigned from the ECU via the Volt output of the AFM and the AFM volt transfer function. So this function does: AFM Volt -> Q . n is the rpm and K the injection constant (which i don't know where is it stored in the eprom, nor if its tuning can be effective if you are running the stock injectors).
The calculated IT is then compared in the PT table with the values stored in the load scale (they are IT values from 1.00 to 5.40ms) and the current rpm value.
So the correction to the IT is chosen among the 256 possible values.
In the end the actual IT* will be IT*=IT x it where "it" is the correction that can have a value from 0 to 2 (convert HEX in the table to DEC and divide by 128).
I started with a crappy setup, like this:
and end with this:
In the first case the possibility of tuning the idle signal (i set it @ 1,5V) by rotating D the driving shaft helps the fuelling correction (the stock AFM reads >2V @ Partial Trhottle, PT), in the second case it was a little more complicated, in fact the sensor can't be adjusted cause it has a idle/WOT switch function also (two plugs, one is a straight fit in the stock TPS female 3 pins). So it has to "click" @ idle and this put a limit to the idle speed signal (about 0,5V).
So in some way you have to increase the Q parameter by managing the AFM transfer function (i've found a excel file on the web to do it).
If you don't do that (or don't do other things which i don't know) the engine will stall (excessively lean due to the low Volt input).
Enriching only the it table won't do the job.
In both cases you will have to work on the PT it tables also.
In both cases i could find a configuration which worked outputting a steady A/F ratio and a smooth driving (i also gifted a couple of 320is users with the .bin files with a BIG disclaimer, they where satisfied 
) but there is always something that doesn't make sense (on the emulator reading) and to which i wasn't able to find a solution, like, in the second setup, when increasing to the maximum the load output, by pushing on the gas till the WOT, the emulator tracking light, on the PT tables, first move to the end of the table (as it must) and just one second before touching the end it jumps back to the beginning like the ECU is now reading low loads(?). This doesn't seem to have any effect on the A/F ratio, but i don't know if it is an emulator problem or my incorrect choice of the engine parameters (bet on the second ).
This is not happening with the AFM, even if the tracking light bounce everywhere in the PT corrections table, at high loads it is quite stuck where it is supposed to be.
In point of fact i didn't get things right, the interaction between the AFM transfer function, the load scale, the minimum and maximum values of load, the PT load scale, seems to be much more complicated than what i heve reported above. So the car goes, but i don't know exactly why and this is remarked by the fact that when i remove the A-N and reinstall the stock configuration, i can clearly feel things get better.
That is what i said to the 320is users who use my setup: "are you sure that the car is running better?" .
This is the link to the way i fitted the Ostrich Emulator in the 320is ECU:
http://freeforumzone.leonardo.it/discus ... dd=8880294
I own a 320is e30 and i was registered in the old forum.
I spent a few years (actually weeks considering that i didn't work on it 24h a day
) in the study of the Motronic software, trying to adjust it via the Ostrich eprom emulator to make the engine running removing the stock AFM and replacing it with a potentiometer (standard alpha n setup).I have also a wide band lambda sensor + gauge.
I partially succeeded: i only could achieve the same stock power, no significant gain in terms of torque or torque moving along in the rpm range.
As far as i know the main injection algorithm is IT=Q/(nxK) where IT is the Injection Timing, Q is the "airflow parameter" which is assigned from the ECU via the Volt output of the AFM and the AFM volt transfer function. So this function does: AFM Volt -> Q . n is the rpm and K the injection constant (which i don't know where is it stored in the eprom, nor if its tuning can be effective if you are running the stock injectors).
The calculated IT is then compared in the PT table with the values stored in the load scale (they are IT values from 1.00 to 5.40ms) and the current rpm value.
So the correction to the IT is chosen among the 256 possible values.
In the end the actual IT* will be IT*=IT x it where "it" is the correction that can have a value from 0 to 2 (convert HEX in the table to DEC and divide by 128).
I started with a crappy setup, like this:
and end with this:
In the first case the possibility of tuning the idle signal (i set it @ 1,5V) by rotating D the driving shaft helps the fuelling correction (the stock AFM reads >2V @ Partial Trhottle, PT), in the second case it was a little more complicated, in fact the sensor can't be adjusted cause it has a idle/WOT switch function also (two plugs, one is a straight fit in the stock TPS female 3 pins). So it has to "click" @ idle and this put a limit to the idle speed signal (about 0,5V).
So in some way you have to increase the Q parameter by managing the AFM transfer function (i've found a excel file on the web to do it).
If you don't do that (or don't do other things which i don't know) the engine will stall (excessively lean due to the low Volt input).
Enriching only the it table won't do the job.
In both cases you will have to work on the PT it tables also.
In both cases i could find a configuration which worked outputting a steady A/F ratio and a smooth driving (i also gifted a couple of 320is users with the .bin files with a BIG disclaimer
, they where satisfied ) but there is always something that doesn't make sense (on the emulator reading) and to which i wasn't able to find a solution, like, in the second setup, when increasing to the maximum the load output, by pushing on the gas till the WOT, the emulator tracking light, on the PT tables, first move to the end of the table (as it must) and just one second before touching the end it jumps back to the beginning like the ECU is now reading low loads(?). This doesn't seem to have any effect on the A/F ratio, but i don't know if it is an emulator problem or my incorrect choice of the engine parameters (bet on the second ).This is not happening with the AFM, even if the tracking light bounce everywhere in the PT corrections table, at high loads it is quite stuck where it is supposed to be.
In point of fact i didn't get things right, the interaction between the AFM transfer function, the load scale, the minimum and maximum values of load, the PT load scale, seems to be much more complicated than what i heve reported above. So the car goes, but i don't know exactly why
and this is remarked by the fact that when i remove the A-N and reinstall the stock configuration, i can clearly feel things get better.That is what i said to the 320is users who use my setup: "are you sure that the car is running better?"
.This is the link to the way i fitted the Ostrich Emulator in the 320is ECU:
http://freeforumzone.leonardo.it/discus ... dd=8880294