AEM 30-6821 Series 2 Plug & Play EMS - Manual (Page 4)

Page 4 of 21
Variable Valve Control (VVC)
The Variable Valve Control table in the
EMS can be used to control the STI’s AVCS system,
which is used to change the airflow characteristics of the engine by advancing the timing of
the intake camshafts. The AVCS outputs (pin A28-A29, Injector 9-10 outputs on the EMS)
advance the phase angle of the intake camshafts; this will have effects similar to moving an
adjustable intake cam gear. This is controlled by the VVC 1 (RH camshaft) and VVC 1B (LH
camshaft) outputs; VVC position is monitored using the T2 and T3 inputs for independent
closed-loop feedback. The VVC settings can be adjusted in the VVC tab (which may be
hidden in the default AEM workspace).
This system is active on this EMS when used with the provided startup calibrations and can
be adjusted through the use of the ‘VVC 1 Target’ map. Adjustments to the intake cam timing
are made by changing the values in the ‘VVC 1 Target’ map per Engine RPM and Engine
Load. The values in the ‘VVC 1 Target’ map can vary from 0 degrees for zero intake cam
advance to 50 degrees for full intake cam advance.
The channels ‘VVC 1 Advance’ and
‘VVC 1B Advance’ show the measured position of the camshafts.
WARNING: Improper use of the Variable Valve Control (VVC) in the AEMTuner software can
lead to engine damage!
Be very careful when building or tuning unknown engine combinations or using aftermarket
pistons or valve train components. OEM engines and valve trains are not designed or
manufactured to allow valve to piston interference at certain cam angles. AEM will not be
responsible for engine damage resulting from improper use of the VVC function on engines
with valve trains designed to allow mechanical interference.
Please note that some Subaru camshaft sensors will send ‘false signals’ under some
conditions (often light load and low RPM). This can be observed with an oscilloscope or
high-speed datalogger, and occurs with the stock ECU as well. These false signals will not
cause engine misfires with the Series 2 EMS, but will sometimes be reflected as quick jumps
in the measured ‘VVC 1 Advance’ channels.