Haltech E6M - Manual (Page 64)

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E6H/E6M applies the Battery Voltage Map to increase the injector on-time as the voltage
drops. This map should not be altered unless the system is connected to a fuel injector test
bench that will allow the injectors to be accurately flow tested over a range of battery voltages
and the corrections calculated accordingly.
8.3 The Ignition Coolant Map
The Ignition Coolant Map allows up to 10° advance or retard of the spark timing based on
engine coolant temperature. This Map should only be used if there is a need to adjust the
timing for low or high temperatures.
8.4 The Ignition Inlet Air Temperature Map
This Map allows up to 10° advance or retard of the spark timing based on the inlet air
temperature. Normally this Map would not need to be used, but in some cases such as high
inlet air temperatures on turbo/supercharged engine, retarding the spark may help preserve the
engine.
8.5 Barometric Correction
Note: The description that follows is targeted at advanced applications and
unless you wish to compensate for exhaust back pressure or are using the
throttle position as your load reference we suggest that you set the barometric
lock in the fuel set-up to “disabled” and bypass this section. If using a MAP
sensor for load sensing, barometric compensation is automatic as map sensors
are manifold absolute pressure sensors and the readings compensate for
barometric fluctuations. The only application using MAP sensors that would
require barometric compensation would be when the exhaust back pressure
must be taken into account. If using a MAP sensor we recommend that you set
“Barometric Lock” in the fuel set up page to “disabled” (i.e. barometric
compensation is enabled). However please note that if you are using throttle
position load sensing, instead of a MAP sensor, barometric compensation is
always required, ensure that all the bars of the barometric compensation map is
set to zero before any tuning takes place to ensure proper compensation. The
factory default map is zero. For naturally aspirated engines using throttle
position load sensing, barometric correction can be by means of a 1 Bar MAP
sensor connected to the wiring harness in the normal MAP sensor position.
This map sensor is used to measure barometric pressure and must be left open
to the atmosphere; no connection should be made from the MAP sensor input
to the inlet manifold.
Fluctuations in barometric pressure vary the density of the intake air to the engine. At lower
barometric pressure, the engine cannot breath in as much air, and therefore the amount of fuel
delivered to the engine must be reduced. This is necessary when a large change in altitude is
expected during a driving period (a Hill Climb event such as Pikes Peak in the USA is a good
example). The barometric correction on the E6H/E6M is a powerful and therefore relatively
complicated feature, this section aims to describe the different methods that can be used.