HFS4 with the 5v output to pin 16 on the DME - issues

CantSitStill

Private
Jul 22, 2022
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Hello!

First post here and I'm hoping someone can help me.

I'm attempting to run a flex fuel map expect based on meth flow instead of ethanol flow. Now this should be fairly easy and Wedge is onboard to help me tune it.

The HFS4 has a 0-5v meth flow output for general use. Much like the twisted tuning meth flow sensor one thats on sale. On Pin 16 with nothing plugged in to it I reads 4v in MHD. This is normal.

The HFS4 reads 0.5v with no meth flow if I read it directly from the controller pins with nothing plugged in to it. Again this is as it should be.

The issue comes when I connect the HFS4 output to the DME pin 16. The voltage reading then drops in MHD to 3v or just below. So it's like the HFS4 output does not have the current to override the DME voltage and I'm getting some reading in between but I know little about voltages ect.

Can anyone help as to why this might be and what special sauce does the twisted tuning device have that the HFS4 does not? I read another post with the same issue but with the fuel IT ECA. There was no solution at the end.


 

CantSitStill

Private
Jul 22, 2022
32
14
0
Sorted. Needed to increase the HFS4 controller current output with a mod, see my posts later in the thread

 
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