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Author Topic: KFWDKMSN and KLAF tuning  (Read 3771 times)
ktm733
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« on: October 18, 2015, 08:50:00 PM »

Okay I've read over a couple of times and I'm still trying to wrap my head around the meaning and function of these maps
Can someone give me some insight
:KFWDKMSN
:KLAF


Sub-function BMLDKNS: Calculation of the normalised target air mass flows through the throttle plate (msndkoos_w)

The target air mass flow mlsol_w is calculated by multiplying the corrected target cylinder charge rlfgks_w by umsrln_w. Since the engine cylinder charge at start is obtained from the intake manifold, initially, no throttle opening would be required (umsrln_w = KUMSRL x nmot = 0). A minimum air flow through the throttle is predetermined by the threshold KUMSRL x NRLMN so that the throttle does not close at the start and then open when the engine picks up speed. The threshold NRLMN is set to 400 rpm since that is assumed to be the engine speed at start. The threshold NRLMNLLR is disabled so that the throttle will be closed during a speed drop, for instance when starting up.

The target air mass flow is reduced by the air mass flow which is directed into the intake manifold through the fuel tank breather (mste) since this amount must be made up via the throttle. The normalized air mass flow through the throttle (msndks_w) is calculated by dividing the target air mass flow through the throttle (msdks_w) by the corrected density, KLAF. The throttle valve actuator air bleed (msndko_w) will still be subtracted from this air mass flow via an adaptation in the function BGMSZS to obtain the normalized air mass that will flow through the throttle (msndkoos_w).

The discharge characteristic, KLAF, is addressed with the target pressure ratio psspvdkb_w. This target pressure ratio comprises the minimum of psspvdk_w = pssol_w / pvdkr_w (turbo) or psspvdk_w = pssol_w / pvdk_w (normally-aspirated engine) and PSPVDKUG together. This means that the target throttle angle only up to the unrestricted range, psspvdkb_w = 0.95 = PSPVDKUG, is calculated via KLAF. The remaining 5% is calculated in the sub-function WDKSUGDS for a normally-aspirated engine and in the sub-function WDKSUGDT for a turbocharged engine. If psspvdk_w > PSPVDKUG, condition flag B_klafbg will be set indicating that the characteristic KLAF is limited.

Sub-function BWDKSGV: Target throttle angle (wdksgv_w)

In this sub-function, the target angle (wdksgv_w) for controlling the throttle plate is calculated from the normalized target air mass (msndkoos_w). Up to the throttle angle for unrestricted operation wdkugd_w (output from the speed dependent characteristic WDKUGDN from the function %BGMSZS) the target angle is determined via the map KFWDKMSN. This is the inverse map of KFMSNWDK (from the function %BGMSZS) and is calibrated to the built-in throttle actuator. If the calculated value of the normalized target air mass flow from KFWDKMSN is greater than the angle wdkugd_w, then the condition for unrestricted operating B_ugds = true.
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