Quote:
Originally Posted by GregWeld
Neither one of my 8 stack motors run a vacuum referenced fuel regulator.... and both run EZ EFI.
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You have to run a vac reference to the regulator because the EZ does know how much fuel pressure you are running. If you don't it wont work properly.
All engines with EFI should have the vac referenced to the regulator.. here is why.
You are trying to tune the fuel curve. If the pressure/vac below the injector changes.. and it does, if you don't compensate for that you will be tuning the fuel curve and the pressure differential too. By keeping the pressure differential constant the ecu just tunes around the actual fuel curve and not the curve and pressure differential. Pressure across the injector remains the same.
This is a basic setting on the EZ that "Bob" forgets. When you enter the fuel pressure in the hand held, it is asking that because it is using the engine vac to determine what the fuel pressure is and tuning based on that.
This is basic EFI101 but even some of the "experienced tuners" out there miss this one.