Print Page - NA to SC throttle / my TB study and how i fixed part throttle

its been about 4 months but i got my car working 100% as it should. med9 has a trick that i dont think me7 has because nobody had pointed it, so i had to go and find it, and now im bringing it here. this is not IDEAL, but it WORKS. call it what you want, a hackjob, or whatever, it works 100%. and i do intend to make a more elegant solution as prj said, implementing a multiplier to the TB flow maps, but for now, at least the car drives fine. i think posting this here will help more than harm.

in summary: yes, you need to tune KFMIRL, KFMIOP. yes, you need to tune TB maps (KFMSNWDKVP and KFWDKMSNVP), because the flow that the TB sees now is higher because of boost. no, it is not ideal, because these maps are originally created in a bench, and they use the speed of sound, and blablabla, but lets be real, theres a fkin air blower pushing power into an engine, so that ship has sailed. if someone needs info on these, i can reply here, but theres material about them all over here. what helped me was understanding its not about just increasing shit just because. you gotta log the inputs, which ill talk about in a minute, and that helps you tune them very easily, just by seeing how much the TB is opening from it. its not the end of the world.

first of all, understand the TB angle dont just come from one place. even the same map can have different input and provide different variables as outputs. this is basic stuff but im trying to cover everything i learned to this point. so here goes the FR sections that are important to us:

In BGWDKHF (Calculation of throttle valve angle from signal of main filling sensor):
(http://nefariousmotorsports.com/forum/index.php?action=dlattach;topic=22803.0;attach=39920;image)
KFWDKMSNVP (Throttle valve setpoint angle). X: msnhf_w Y: pspvdb_w
In general, either an HFM and/or an intake manifold pressure sensor is necessarily present as the main filling sensor for filling detection […] to calculate the angle of the throttle valve. As long as this calculated throttle valve angle [wdkhfu_w] is smaller than the throttle valve angle that is reached at 95% filling [wdkugd_w], the calculation model provides the correct throttle valve angle for throttled operation, provided there is no error in the filling sensor. If this angle is exceeded, the condition B_wdkhfu (unthrottled operation) is fulfilled. The calculated throttle angle wdkhf_w [now wdkugd_w] is valid and can be evaluated by other functions if the main sensor is ready for operation and throttled operation is present. The validity is indicated by the bit B_wdkhfg.

In FUEDK:
(http://nefariousmotorsports.com/forum/index.php?action=dlattach;topic=22803.0;attach=39928;image)
The target mass flow msdks_w is converted into a target standard mass flow via a division with umsnms_w (conversion of mass flow into standard mass flow). The air leakage ofmsndk_w learned via an adaptation in the %BGFKMS function is subtracted from this air mass flow and the standardized air mass flow msndkoos_w is obtained, which should flow via the throttle valve. With the map KFWDKMSNVP (inverse map to KFMSNWDKVP in %BGMSDK), the target standard mass flow is converted into a target throttle valve angle wdksbugd_w.

In BGMSUGD:
(http://nefariousmotorsports.com/forum/index.php?action=dlattach;topic=22803.0;attach=39922;image)
FKLAFUGD Output from KLAF for PSPVDKUG [originally 0.45. this is limited, after scaling, to 1.99 (FFFF)]
KFWDKMSNVP X: msndkoug_w Y: pspvdkug_w (Throttle valve setpoint angle)
WDKUGDN X: nmot_w (Throttle valve angle above which throttling no longer takes place)
This function calculates the mass flow rates at the throttle valve and EGR valve, at the unthrottled valve and when the valves are fully open. Unthrottled means that the pressure ratio from before to after the valve corresponds to 0.95 (PSPVDKUG). From this pressure ratio, […] the mass flow is calculated linearly from this point up to a pressure ratio of 1. For this linearization, the mass flow rates at UGD and with the damper completely open are required.
In the following drawing file, an unthrottled angle is calculated from the unthrottled throttle valve mass flow (analogous to the calculation throttle valve target mass flow - throttle valve angle).
(http://nefariousmotorsports.com/forum/index.php?action=dlattach;topic=22803.0;attach=39924;image)
(http://nefariousmotorsports.com/forum/index.php?action=dlattach;topic=22803.0;attach=39926;image)

[…] The mass flow is calculated at a pressure ratio of 0.95 at the throttle valve and EGR valve. The calculation is based on the following assumption:
Case 1: no EGR installed (SY_AGR=0):
psdkugd = 0.95 * pvdkds
rforidug = (psdkugd - pbrintug)*fupsrlug [for SY_DSS = 0]
The problem here is that pvdkds (Pressure before throttle valve from pressure sensor) comes from the atmospheric pressure. It is a calculated theoretical mass flow, not something that can be edited in a map. so everything from now on fucks with us, because our mass flow will be way higher than this guy that is calculated in OEM conditions.
so here comes my hackjob. my part throttle issues were being caused by the following portions, that come from the map that is the INVERSE of the one we've been talking about: KFMSNWDKVP. this gets the TB angle, and provides the corresponding air flow. so if you get one right, just copy paste the numbers into the other one, and you're good. but its not enough, because:

In BGMSDK:
(http://nefariousmotorsports.com/forum/index.php?action=dlattach;topic=22803.0;attach=39930;image)

In BGRLP:
(http://nefariousmotorsports.com/forum/index.php?action=dlattach;topic=22803.0;attach=39932;image)

YES, both portions compare the theoretical value i mentioned above (wdkugd_w) to whatever is obtained from real airmass flow, and proceeds with the MINIMUM between them. this means that whenever i got boost, my TB simply wouldn't open further, because wdkugd_w was following atmospheric pressure, up until a point where the ecu goes into alpha-n and then it just opened all at once. this means i had 0-~25% TB ok, then a gap from ~25% to 55% TB. like an on off switch, that went from ~25% TB and 0bar, to ~55% TB and 0.4 bar. the problem wasnt even how it opened, the feeling is like a turbo kicking in. the problem is that given the huge gap, any slight press/depress of the pedal made it kick in or close, so coming out a slow situation, such as 3rd gear leaving a roundabout.

enough talking, how i fixed it? if you notice the screenshot from the BGMSUGD routine, you'll see the input (msdkugd_w) is divided by a multiplication between FKLAFGD and frhovdk_w. frhovdk_w comes from ftvdk_w which in turn, comes from FTVDKTAVDK (Temperature factor for throttle valve flow). while FKLAFGD, is a 1x1 map, that simply contains the value from KLAF's axis corresponding to 0.95 (which is the limit between operating modes for the ECU). no idea why its got this constant value being set here, instead of just reading KLAF@0.95, but i dont care. maybe it would be less-costly, cpu-wise. well, all i did was log what i had as a theoretical output from this guy, in kg/s, and how much i had as actual airflow mass, just to see its about 3x more in most curve.
***keep in mind what im doing here will only work well if you have everything else well calibrated. why? because if by any chance you make wdkugd_w too high, it wont matter as the TB % comes from the other MINIMUM value. if its the opposite, and wdkugd_w is still the minimum value, by raising it here, at least it will be MUCH closer to reality and wont fuck your part throttle.

so since i wanted to raise my theoretical mass air flow value by 3x, i just divided FKLAFGD by 3. it was 0.45 and now its 0.15. this removed the ceiling i had reached because of wdkugd_w and now my TB works PERFECTLY as expected. zero hickups, zero gaps, no on/off.

hope this helps someone, someday. and i promise when i finish a more elegant solution to actually multiply the airflow by the boost, ill post here as well. so far im thinking of using pspvdk_w. its works as an absolute pressure theoretical value (since my car has no MAP sensor in the manifold), calculated from the MAF, but it seems to be very much in line with reality. im running 0.7 bar boost, and pspvdk_w shows ~1.702179 values. also matches lower boost numbers. so based on what PRJ said about using a multiplier into the tb airflow maps, ill study this as a solution. however, just eyeballing it, theres something else behind the math because to tune my airflow tables i didnt just multiply the values by how much more pressure i had in each point. i.e., for 18% tb, i more than doubled the air mass (130% increment), while for 23% TB, there was an 80% increment. if PRJ wants to help with directions here, id appreciate it, as i know he has tuned properly a PES kit in the past, without adding MAP sensor.

NefMoto

Technical => Tuning => Topic started by: lgtmelo on May 03, 2024, 01:41:05 PM