Looking to buy an HFS-4, Question on configuration?

[Onetechyguy]

Hi,

I'm looking to buy the HFS-4 for my 2007 Mazdaspeed 3. I have to choose between two different vendors. My question is are the HFS-4's universal other than using the diagram for my specific car or does the unit need to be modified (soldered) to work with my application? Or do I just buy the unit from anyone and just install it? Thanks. Rick

[Richard L]

If you are buying the latest stock, HFS4-v3.1, there is no soldering required. The 2.5x pre-scaler and done by jumper links.

[Onetechyguy]

Ok, Thanks. I will make sure I buy that version.

What is the 2.5x pre-scaler? Will the wiring diagram for my vehicle tell me how to set the jumper for that?

[Richard L]

The 2.5x pre-scaler is for scaling up the duty cycle % of a direct injection engine. The MS3 maximum duty cycle is 30-33% at. This is because fuel is only injected when the inlet valve is shut, duration of spray is limited.