Haltech Platinum Interceptor - Manual (Page 9)

Interceptor Manual
9
made, resulting in the factory ECU base maps being well away from the required stoichiometric
fuel mixture. Modifications that would likely cause this are: larger injectors, higher fuel
pressure, modified cams etc.
Basic Ignition Tuning
Haltech Interceptor ignition tuning is quite consistent in its response across all vehicle
applications. The units in the internal tables are in degrees that are then added to the ignition
timing generated by the factory ECU ignition tables. It is important to realise that the ignition
tables are a correction, and not the actual ignition timing being run. The factory ECU should be
quite close to the desired ignition timing on an unmodified car, but performance gains can be
made if tuning for higher quality fuels or the factory ECU tune is very conservative. If the
engine is modified, large power gains may be possible. As always, it is important to monitor for
any pinging that may occur with too much ignition advance.
Unlike fuel corrections, ignition corrections can generally be made at any load and RPM site, as
there is no closed loop control of ignition timing. Often the factory ECU can be very
conservative at light loads, and noticeable gains in throttle response can be achieved with
additional ignition advance in these areas.
Knock Control
Many factory ECUs employ knock control to prevent engine damage due to pinging. Generally
the factory ECU will monitor pinging using the knock sensor and retard ignition timing to get
rid of it. The problem with this for the Haltech Interceptor is that in the quest for more power, a
tuner may advance the ignition timing, but this may cause pinging. The factory ECU then
retards the timing to get rid of the pinging, and the result is that the power curve becomes
inconsistent and makes no more power. Haltech recommends that before applying advance, the
tuner should retard the ignition timing to see if power is lost. If power is lost, then the advance
can be gradually added until max power is reached. It is recommended that the tuner run the
minimum advance that achieves the performance requirements. Haltech has found on several
cars that maximum power was achieved with ignition retarded from the factory ignition curves,
as the factory ECU was tuned to run on the verge of knock control all the time. Therefore more
power was made by pulling the ignition advance back to a level that would prevent knock
control operation and still make good power.
Diagnostic Scan Tools
Haltech strongly recommends the use of diagnostic scan tools to aid in the tuning of the Haltech
Interceptor. Some of the issues mentioned above can be easily diagnosed and worked around
with knowledge of the correction factors and modes of the factory ECU. The following
parameters can be very useful whilst tuning a Haltech Interceptor: