I've explained in other articles the benefits to measuring
fuel pressure; firstly it allows you to monitor the health of
your fuel system but more importantly it allows the ECU to know
the fuel pressure seen by the injectors, and therefore how long
the injection pulse needs to be to deliver a given volume of
fuel. So we highly recommend adding a fuel pressure sensor when
installing an ECU.
Most modified RX7s tend to convert to at least the secondary
injectors to top-feed style to increase the flow. Because the
factory fuel pressure regulator is mounted on the secondary
rail, this means that normally an aftermarket fuel pressure
regulator is added.
This provides a convenient place to connect a fuel pressure
sensor; because almost all aftermarket regulators have a 1/8 NPT
fitting into which you can screw a gauge. So it's very simple to
screw a pressure sensor into that location instead. The sensors
we sell are 0-150 PSI gauge pressure; you can use other sensors
but you must ensure they are rated for fuel use.
Once you've mounted the fuel pressure sensor and checked
for leaks, you can wire it in. There are two ways to do this if
you're using a plug and play ECU. The first is to wire it into
the dedicated fuel pressure input pin on the ECU. Cut the wire
that goes out to the loom, and connect the signal output of the
sensor to this pin. Then Tee the 5 Volt and sensor ground
connections to those that go to the TPS, MOP sensor and so on.
You can find these pins on the diagram in the software.
The alternate method is to wire the fuel pressure sensor
into the factory MAP sensor wires, and use the internal MAP
sensor in the ECU to measure manifold pressure. If you do this,
you'll need to select the (d) source for the fuel pressure as
coming from the external IMAP (intake manifold absolute
pressure) input.
To change the source and sensor type go to (a)" Input"
tab in Home Ribbon, then (b) select "Fuel Pressure Sensor".
You'll also need to (c) select the sensor type - 0 - 150
PSI gauge being the most common, and once you're satisfied it's
reading correctly, Select the fuel pressure as being "measured"
as opposed to "nominal" in the software, and the ECU will
automatically take the fuel pressure into account when
calculating the injector pulsewidth.
To change fuel pressure modeling, go to (a) "Output"
tab in Home Ribbon, then (b) select "Fuel System"