Q-generation STAG - LPG intelligent controllers

Q-generation STAG - LPG intelligent controllers

All new LPG controllers deciding on the strength of AC's current offer, not only in the Polish market, are referred to as Q-generation.

All Q-generation STAG controllers are built on new hardware platforms fitted with 32-bit processors dedicated for automotive applications and adapted to difficult operating conditions inside car engine compartments.

Memory size has been increased, thus allowing increasing Q-generation controller computing capacity  with a large excess enabling future extension.

Thus, a number of additional functions and components being separate units could be integrated into them.

Therefore, Q-generation has the chance to stay longer in the AC S.A. offer, especially since controllers are intended for software upgrading.

The modern hardware platform of new AC controllers enables implementation of advanced functions, including OBD auto-adaptation and ISA3 systems.

They have been developed to provide gas fuel dosing of the highest accuracy that is especially important due to accurate exhaust gas emission control systems used in modern  drive units. They detect any fuel dose imprecisely measured by the injection system as a fault.

Switching on the OBD auto-adaptation causes that the gas supply system doses LPG according to engine operating conditions and load, based not only on petrol injection timing, but using the petrol controller OBD corrections. Thus, fuel dosage is adjusted to the demand of the engine during normal use of the car.

The Intelligent Auto-adaptation System ISA 3 works in a similar manner in real time. With this system the gas map is created based on the petrol injection timing map acquired automatically within the full load range.

When the engine is later LPG fuelled, the system compares how petrol injection timing changes depending on the pressure inside the intake manifold (engine load).


Thus, if petrol injection times become longer within a specified load range, this indicates a lean mixture. The system starts to correct gas dosage, creating an additional map of corrections to the petrol injection map collected earlier.

The map is modified in real time depending on the engine crankshaft rotational speed and vacuum pressure, regardless of RPM correction to injection times.

When the reference petrol injection map is acquired, also engine temperature is taken into account. Also ISA3 recognizes the engine operating mode (loop status). Thus, the AFR is monitored all the time both during closed loop and open loop. Therefore, the gas-fuelled engine operating in open loop is always fed with a rich mixture, like for petrol fuelling. So, the risk of drive unit operation on a lean mixture is eliminated.

Switching on ISA3 does not exclude the use of OBD corrections. ISA 3 does not need them to operate but they can be displayed in the program and used for manual adjustment.

Both systems are particular about supplying the engine with a proper air/fuel mixture to minimise the risk of adverse effects of variable operating conditions, wear of the fuel system components due to LPG dosage changes.

Due to ISA3, older cars (without OBD system) get the chance to correct LPG dosage in real time. The fuel dosage will be automatically adjusted, e.g. to wearing autogas system components or varying gas fuel composition. The maximum correction is ±25%.

The new Q-generation AC controllers are equipped with one more interesting automatic system.

This is automatic OBD error acknowledgement system.  The cancelled errors must be previously strictly defined by the fitter who commissioned the system.

This is a useful option enabling errors unimportant for the safety of a drive unit, but being cause of concern to car users and unnecessary visits to service centres.

« back