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RPM Ignition
This is where the main ignition timing is programmed. There are 38
Rpm ranges in total just 4 are shown in photos above. The first 3
are always 500,750 and 1000. Above that RPM steps are in 100,
250 or 400 increments, with RPM RANGE settings of 4500, 9750,
or 15,000 respectively.
Ignition Programming
Ignition timing requirements differ widely between various types of
engines and fuels used so we can only offer general guidelines for
ignition values.
SERIOUS ENGINE DAMAGE CAN OCCUR with
improper values entered.
Excessively retarded timing can cause
high exhaust gas temperatures while advanced timing can lead to
pre-ignition and detonation.
Default values may not be correct
for your engine!
Ignition Advance and Retard vs.
Load(manifold pressure)
These 64 settings allow programming of ignition retard or advance
with reference to load on the engine. Load information is from the
MAP sensor. RET refers to retard, and ADV refers to advance.
RETard reduces timing, usually done at higher MAP to prevent
detonation (left photo above).
ADVance adds to your timing, usually at lower MAP to help fuel
economy (right photo above).
ADVance will be added to RPM IGN, RETard will get subtracted
from RPM IGN.
If too much retard is programmed, power output from the engine
may be reduced significantly.
Advance may be useful to improve fuel economy. Advance can be
programmed by pushing the minus key.
To the right is a generic example timing map to show how
RPM Ignition and the RET-ADV/LOAD work together.
Some
advance is used under low MAP to help fuel economy, and some
retard at high MAP to help prevent detonation. The CPi2 will read
engine RPM and lookup the RPM timing for that RPM range. Next
the CPi2 will read the Manifold pressure via the Map sensor, and
lookup the RET-ADV for that Manifold pressure range. Software
uses the RPM Ignition amount and adds Advance or subtracts
Retard from the manifold chart to get the final timing.
Example: RPM is say, 1600, RPM Igniton=23, and lets say manifold
pressure is at 21.9” where we have 3 deg Advance, so total timing
will be 23+3Adv=26 degrees. Another example, RPM=1500, RPM
Ignition=23, Manifold pressure at 38.1”, 4 Ret, so 23 minus Retard
of 4 = 19 Degrees total timing.
