Frequency MAF sensor

Hi,
i want to use a Bosch HFM6 MAF sensor, which outputs a frequency signal.
That is the characteristics curve:


Sadly the MAF sensor input doesn’t allow me to use a digital input as frequency input. Is it possible to add this to the SW?
I atm workarounded it by connecting it to Turboshaftspeedsensor Digital 5 and set MAF as a function of Turboshaftspeedfrequency:


…but i don’t like this solution.

In addition this MAF sensor outputs also a low frequency signal as a corrective faktor for the airmassflow (in original SW something like temperature correction is written). The frequency is around 20Hz. Sadly the emu pro seems not to be prepared for low frequencies, since all frequency inputs have the unit kHz, which results in too small numbers to handle them.
So is it possible to add custom inputs which give the possibility to read low frequencies?
I think this could also be useful for other stuff.
Best regards

Hi,
Please provide the datasheet for that sensor.
Is this low-frequency signal just another wire for a separate digital input?

We can add a frequency signal type for the MAF sensor.
We have something similar for the accelerator position sensor.

Hi,
yes it is a seperate wire to a digital input.
So 2 signals…main signal and corrective signal.
It is a Bosch HFM 6. I actually don’t have a datasheet for it and can’t find any in the internet. I got my infos from OEM SW Docu and stock engine calibration (Audi S5 V8 with MED9.1 ECU) and verified it with measurements on the vehicle.
Let me summarize all data i have…maybe it helps someone else:
HFM 6 with Bosch PN 0 280 218 214
It is wired to MED9.1 like that:


Pin1: Airmass main signal (frequency)
Pin2: Korrektive factor for main signal (frequency)
Pin3: IAT signal
Pin4: ground
Pin5: +12V supply

From OEM calibration i got the characteristic curve for main signal:

Bosch HFM 6 seems to be availbale in 2 versions and from the MED9.1 SW docu i got the infos for the corrective signal:


with the subfunction for correction TPKMHFM_W:

tpmshfm_w = frequency/periode duration of main signal
tpkhfm_w = frequency/periode duration of corrective signal
tpkmhfm_w = corrected frequency/periode duration of main signal
mshfma_w = airmassflow
MSHFMTPH = characteristiccurve of the sensor
TPSOLL is a reference periode duration/frequency for calculating the corrective faktor. In my case the oem dataset showed 52ms=19,23Hz and i confirmed this by vehicle measurement.
In my engine this value was always at 52ms and also in OEM there seem to be versions without this according the SW docu, so i guess it is no neckbraker to not have it. But it would be nice to at least have the possibility to add it via a costum frequency input and then somehow a 3D table in MAF characteristic curve.