MSD 2957 Atomic LS Master Early Truck Kit (GEN III 1999-2007) Installation - Manual (Page 18)

18 INSTALLATION INSTRUCTIONS
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A/F Targets: The Atomic LS provides an option to set an air/fuel
target for Idle, Part Throttle, Wide Open (WOT), Nitrous
and Boost. The Atomic will use its self-learning technology
to adjust the fuel delivery to meet the target air/fuel ratio.
The values are adjusted in 0.1 increments and range from
rich at 10:1 to dead lean at 16:1. The ideal air/fuel ratio for
cruising is called stoichiometric and is commonly referred
as a 14.7:1 air/fuel ratio.
Boost: The Atomic will switch to the commanded boost
A/F ratio once the manifold pressure reaches
110Kpa (approximately 16 psia - 32.5in/Hg)
(Figure 32).
Ignition Timing: The Atomic provides a base timing table for each
engine application. You can also modify these settings at
idle (closed throttle), part throttle, wide open throttle (WOT),
nitrous, and boost. Each setting is adjustable +/-10°. Note
that the values programmed are set for stock engines using
91 octane fuel. For lower octane fuels it is recommended
to retard the timing 5° as a starting point. Timing can be
retarded up to 20° in 0.1° increments. Note that in order
to alter the timing for nitrous use, the Nitrous Selection in
the Advanced menu MUST be programmed to ENABLE.
When the nitrous is activated by supplying 12 volts to the
Brown/White (Pin C) wire the timing will retard (Figure 32).
TPS Enrichment: To assist in throttle transitions the Atomic EFI
has a feature to increase fuel delivery by a prescribed
percentage any time there is an increase in throttle
position. If needed, make small changes in no more than
5% increments without further testing. Most engines will
find 25% sufficient. Most applications will accept 15%-35%
enrichment. Adjustable from 0-100% in 1% increments
(Figure 32).
MAP Enrichment: To assist in manifold pressure transitions the
Atomic EFI offers a MAP enrichment feature. This function
adds fuel based on MAP transitions while moving the
throttle. Large cam vehicles with low vacuum generally
required a slightly smaller number while stock/small
camshaft vehicles with a high vacuum may require more.
If needed make small changes of no more than 5%
increments without further testing, 25% is sufficient for
most engines but between 15-35% is normal. Typically,
the higher the vacuum the higher the percentage needed.
Adjustable from 0-100% in 1% increments (Figure 32).
2-Step: This setting will rev-limit the engine at the programmed
RPM when the Blue wire is activated with 12V. The 2-Step
setting is used in drag racing applications to help launch
the car at a consistant RPM. The blue wire is normally
connected to a clutch switch or a brake switch. The default
setting is 10,000 RPM and can be adjusted from 1000
RPM to 7500 RPM in 25 RPM increments (Figure 32). The
ignition cut should only be used on race vehicles with a
very free flowing exhaust. DO NOT use with catalytic
converters or severe damage may result!
TPS Enrichment
Igniton Timing
A/F Targets
Figure 32
MAP Enrichment Setting
2-Step RPM Limit