Idle and part load fuel map tuning

[nyb]

Hi guys ,

Would someone please guide me to the right maps in Tuner Pro that need to be modified to enrichen part load maps on the MSS54HP that currently runs on a CSL US map?
The engine has on the intake side a Cat Cam 280 and stock S54 exhaust . So far managed to alter the fueling map KF_TI_N_RF_VL while on a dyno session and i was able to richen the mixture but at part load KF_TI_N_RF_WL (is this map the the part load KF_TI_N_RF_WL?) no matter what i did i was not able to correct the fueling . During cold start enrichment AFR stays between 13.6- 14.5 afr and as soon as it engine is warming up 50-60 degrees F ( engine temp) mixture goes to 16 -17 AFR ) .I have attached a screenshot of a log ( throttle vs AFR ) . The o2 sensor logger is correctly calibrated and displaying correct values .
Much appreciated ,
Adrian

[R3VM3UP]

Are you running CSL software with a MAP sensor, or are you just attempting to run alpha N on the regular US MAF software?

If you are trying to run alpha-N, I think the map you are probably looking for is KF_RF_N_AQ_REL. I'm pretty sure this is the engine speed (n) vs. throttle angle (or normalized position 0-100%) table that contains base injector pulsewidth. I would expect that at part pedal you should be in closed loop lambda control though, so even if the base fuel calculation is lean, your fuel trims will pull things in a bit. Do you have closed loop fueling disabled? If not, are you 100% sure that your o2 sensors are not swapped bank to bank?

It seems like some of the key fuel and spark portions are missing from the readily available funktionsrahmen docs but if anyone happens to have them I'd be interested.

[nyb]

HI,
Running CSL sw with a map sensor . O2 sensor are not swapped for sure . Where would i go on on the map to set it at closed loop ? The engine is in a dedicated race car .Going to the track tomorrow for logging and some test and tune for an upcoming race and hope to sort out this 0 to 60% range that it swing a too lean . I am not staying around that throttle opening for too long but i need to correct it .
Much appreciated !
Adrian

[R3VM3UP]

I think I misunderstood the tables I was looking at in my last post. The values in KF_RF_N_AQ_REL are not injector pulsewidth... it appears that this is the primary alpha-n volumetric efficiency table.

KF = map
RF = relative filling
N = engine speed
AQ_REL = relative cross sectional opening

The values in the table seem to represent a normalized captured air charge in the cylinder, where 1 = 100% full. This is referred to as relative filling (RF) in the BMW/Siemens jargon, but is commonly referred to as 'load' in the american auto industry. I believe the CSL software still heavily relies on this table and it's probably the key table that you would need to tune. Higher values in this table mean the DME is calculating that there is more air in the cylinder and it will fuel accordingly. So you'd need to figure out what speed and throttle angles you are having issues with running at and increase the corresponding values in this table.

What modifications have been done to your engine? What MAP sensor are you using, and do you have the correct transfer function calibrated in your tune? How are you measuring AFR? Wideband o2 sensor at the headers? Are you 100% sure you don't have any exhaust leaks?

The reason I asked about whether your O2 sensors might be reversed is because it can wreak havoc on closed loop fueling when this happens. e.g. if sensors are flip flopped and one bank is slightly lean, the closed loop control will try to add fuel to the bank it thinks is lean to get it to stoich, but the controller will be adding fuel to the wrong bank. The lean condition will persist and the controller will keep adding fuel. Meanwhile the other bank will be reading rich and the controls for that bank will do the opposite. A good way to double check that this sort of thing isn't occurring is to just unplug the o2 sensors.