Electromotive xdi, Installation Manual & Users Manual

Page: 26 / 36

XDI Manual Version 1.8 Page 26

2017 Electromotive, Inc.
5.4 External Advance Control
Up to 15 degrees of advance can be externally added to the timing curve. Typically this is used for
vacuum advance (Section 5.4.1) but the user has the flexibility to use this in combination with switches, knobs,
etc. to achieve custom functionality of the system.
The added advance is inversely proportional to the input voltage applied at pin 20 (green wire). This is
shown in Figure 16 .
Input Voltage vs. Additional Advance
0
2
4
6
8
10
12
14
16
0
0
.2
0
.4
0
.6
0
.8
1
1
.2
1
.4
1
.6
1
.8
2
2
.2
2
.4
2
.6
2
.8
3
3
.2
3
.4
3
.6
3
.8
4
4
.2
4
.4
4
.6
4
.8
5
External Voltage Applied at Pin 20 (Green)
A
d
d
it
io
n
a
l
Adv
a
n
c
e
When this wire is left disconnected, the controller defaults to 5V, resulting in 0 degrees of advance.
5.4.1 Vacuum Advance (a.k.a. Boost Retard)
Vacuum advance adjusts the timing based on the load on the engine. It improves engine response over
the entire operating range and brings timing closer to optimum.
The Manifold Absolute Pressure (MAP) Sensor hooks up directly to the XDI's +5V, GND and External
Advance Control wire, giving 15

of advance when the engine makes 30" of vacuum. This advance is in
addition to the knob selected timing.
At idle, vacuum is high (manifold pressure is low), and the engine wants more advance since cylinder
pressures are low. At wide-open throttle, vacuum is low (manifold pressure is high) and no additional timing is
added. You should retune your timing curve after adding a MAP sensor.
5.5 External Retard Control
Up to 30 degrees of timing can be subtracted from the timing curve. This can be used for nitrous retard
or for any other situation where variable amount of timing must be removed. The amount of timing removed
from the timing curve is proportional to the input voltage at pin 13 (orange wire). If this wire is left
disconnected, it will default to 0 volts and no timing will be removed. This is shown in
Figure 18 .
Figure 16
-
Graph of
input voltage
vs.
additional
advance
Figure 17
MAP sensor
connection