Frelander 2. Manual - part 305
The position of the inlet camshaft is determined by the ECM using signals from the CKP sensor and the CMP sensors. The
ECM can then use the VCT solenoid valve to control the angle of the camshaft by controlling the flow of oil to the VCT unit.
The camshaft is secured to the rotor in the VCT unit. Oil pressure supplied to either side of the VCT unit from the VCT
solenoid valve can rotate the rotor and hence the camshaft in either direction. The VCT solenoid is operated by the ECM
using PWM, high frequency switching which provides rapid and precise control of the inlet camshaft position. The inlet
camshaft position can be adjusted within 40 degrees of crankshaft rotation.
Camshaft Profile Switching (CPS) Control
The inlet camshaft has, in addition to the VCT control, a CPS function which is also controlled by the ECM. The CPS control
can vary the valve lift height and duration of the camshaft lobes by adjusting the area of the hydraulic tappet which acts
on one of two cam lobe profiles. The CPS control is via two CPS solenoid valves, located at each end of the inlet camshaft.
The CPS solenoid valves control the position of hydraulic tappet assemblies which can be set in one of two positions; low
and high.
Two CPS solenoids are used so that the hydraulic tappets can be adjusted when no load is applied, for example the cam
lobes are off the hydraulic tappets and the cam base circle is acting on the tappet, this keeps the stress on components to
a minimum. One CPS solenoid supplies oil pressure to the hydraulic tappets of cylinders 1, 2 and 4 and the second CPS
solenoid supplies oil pressure to the tappets of cylinders 3, 5 and 6.
At engine start and at low engine oil temperatures (below 40°C (104°F)) the ECM does not direct engine oil pressure to
the hydraulic tappets and therefore the hydraulic tappets are in their spring loaded, low position.
For additional information, refer to: Engine - 3.2L (303-01, Description and Operation).
Ignition Control
The ECM calculates the optimum ignition timing based on pre-programmed maps and information from the following
sensors:
CKP sensor
CMP sensors
MAF sensor
ECT sensor
Electric throttle TP sensor
Knock sensors
TCM
Ignition coils.
During engine starting the ECM uses a fixed ignition setting. W hen the engine has started and the vehicle is being driven,
the ECM adjusts the ignition timing accordingly using other parameters such as engine speed, load and temperature.
Once the engine has reached its normal operating temperature, the ECM monitors the signals from the knock sensors. If
any of the cylinders produce knocking, the ignition timing for that cylinder will be retarded until the knocking has stopped.
The ignition is then gradually advanced back to the normal timing or until the knocking re-occurs.
The ECM uses information from the TCM to provide torque limitation during transmission shifts. The ignition timing is
adjusted to momentarily reduce the engine torque output to give a smooth transmission shift and reduce load on the
transmission.
Air Conditioning (A/C) Compressor Control
The ECM controls the operation of the A/C compressor and reacts to requests from the ATC module via the high speed CAN
bus. The compressor is a variable displacement unit and the ECM controls, via a solenoid, the displacement of the
compressor to adjust load during certain driving conditions.
During engine start-up, moving from a standstill and under hard acceleration, the ECM sets the minimum displacement of
the compressor to reduce the effect on the engine torque output. The ECM uses information from the ATC module, the A/C
pressure sensor, the electric throttle TP sensor and the ECT sensor to determine compressor control. The ATC module
transmits climate control and driver requests to the ECM and the ECM determines the priority of these requests over
engine performance.