OMEM710 Hardware Manual 2v11
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Anti-lag keeps the boost pressure high and the turbocharger spinning by keeping the gas flow high,
but maintains drivability by controlling the torque. The gas flow can be achieved by jacking the
throttle with a solenoid, air bypass valves, or if a low level of anti-lag is used, often by opening the
idle motor. To control torque, the ECU retards the ignition and cuts fuel and sparks.
In reducing engine torque, anti-lag produces very high exhaust gas temperatures which can cause
damage to the manifold and turbo. If using anti-lag, monitor exhaust gas temperature very closely
when setting-up and consult your turbo manufacturer for guidance on maximum temperatures.
When the antilag input is satisfied, three tables are used to maintain engine speed based on throttle
position – an ignition retard table, an ignition cut table, and a fuel cut table. Once the engine speed
exceeds the speed in the table, the relevant soft cut option is invoked. If the speed is exceeded by
50rpm the hard cut option is added to increase the effect. The first torque reducer to use is the
ignition retard, then the ignition cut, and finally if required, the fuel cut.
The Ign Cut RPM table and Fuel Cut RPM table found on the Anti-lag tab are copies of those
found on the Rev Limiters tab.
If using the idle motor to give anti-lag airflow, then the option ALS Idle is the percentage duty cycle
added to the idle motor to open it when the ALS input is satisfied. This would often be 100%.
ALS Air Max is the air temperature above which ALS turns off and the ECU shuts its controlled
valves.
ALS Off Road Speed – If the ECU has a road speed input, this option allows the anti-lag to be
deactivated above a set road speed. This allows the anti-lag to be used as a launch control for
engines that require boost at low RPM for launch.
ALS Active Time is the longest time the ECU will stay in anti-lag mode before turning off to prevent
excessive exhaust gas temperatures if coasting downhill. ALS Inhibit Time is the minimum time
after turning anti-lag off that it can turn on again.
It is possible on some engines to create more boost in anti-lag mode by increasing the fuel. This is
done using the ALS Fuel Trim table.
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