MSD 7531 Programmable Digital-7 Plus Installation - Manual (Page 9)

INSTALLATION INSTRUCTIONS 9
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GEAR SELECT
The Three Step Retard wires, Pink (1), Violet (2) and Tan (3) can also be wired to indicate the first
three gear changes to the ignition control. When selected from the Step Wire menu, the ignition will
know that the car is in second gear when 12 volts are applied to the Pink wire, third for the Violet and
fourth when the Tan wire is applied to 12 volts. By using this feature, if you lift off the throttle and get
back on it, the ignition will not count it as a gear change.
Note: When selected, this feature overrides the RPM Drop Gear Select values.
This is a sequenced series meaning Tan (3) will not become active until it sees 12 volts on Pink (1),
and Violet (2). This way, 12 volts do not need to be removed from each wire before the following gear
is selected.
Note: Five and six speed transmissions will have to use the RPM Drop functions for gears 5 - 6.
GEAR RETARDS
This program provides the ability to create a run curve for each gear. Up to six different curves can
be programmed from 800 – 12,500 rpm in 0.1° increments for every 100 rpm. You can program up to
32 different points on each Gear Map. Also, all of these points are interpolated every millisecond to
create a smooth (no steps) curve.
The number of gears is adjustable under the SHIFT menu, as well as the amount of rpm drop the
ignition needs to see before knowing that a different gear has been selected. Up to six gears can be
programmed. You can also use the Step Retard wires as Gear Select Indicators for the first four gears.
These retards are mapped out on the Gear Retard chart of the Graph View. In the chart, go to the
View pull down menu and select Trace Box. That will give you a small window to show the different
color gear traces so creating a different curve for each gear is easier.
If you want the same retard curve for all gears, compose the curve, select the Edit pull down menu
and copy the curve, then select Paste All.
BOOST RETARD CURVE
This timing curve can be programmed in relation to boost/vacuum pressure within the intake manifold.
The curve can be programmed from 2psia - 45psia in 0.25psia from 0°- 25° in 0.1° increments. Up to
32 different points on can be input on the Boost Chart. Also, all of these points are interpolated every
millisecond to create a smooth (no steps) curve. This curve can easily be edited using the Boost
Curve chart in the Pro-Data+ software. An MSD MAP sensor is required to use this feature and three
are offered:
1-Bar, for n/a engines, PN 23111
2-Bar, for 2-30psia, PN 23121
3-Bar, for 2-45psia, PN 23131
Note: The Boost Retard Curve default is 0° retard.
Rev Average: This allows you to program the number of engine revolutions that occur to
produce an average boost value. It is adjustable in 2, 4, 6 or 8 crankshaft revolutions. This
function is designed to help average the boost pressure to provide an accurate reading. The
default is 2 revolutions which should be ideal for the majority of applications.
PSI Sensor: This allows you to input the specification of the MAP sensor. Select a 15psia,
30psia or 45psia sensor. Default is 15psia.