The 3.9 liter and 5.2 liter engines featured a throttle-body fuel injection system which is a computer-regulated single-point system that is controlled through the SMEC which monitors the ignition period, A/F mixture, emission devices, the charger and the idle speed which is also responsible for fault coding. This unit holds the regulator, the fuel injector, the throttle position sensor, the throttle body temperature sensor as well as the idle speed control actuator, in case of the 5.2L engine. Getting to the throttle body, the air cleaner has to be removed, fuel pressure has to be reduced, the negative battery cable has to be disconnected and vacuum hoses and wire harness connectors have to be disconnected and marked. The throttle return spring, accelerator cable and bracket, as well as any speed control cable/transmission kick down linkage should also be removed next; the fuel supply and return hoses should be disconnected and the throttle body bolts loosened to allow lifting of the assembly clear of the intake manifold, a new gasket required when reinstalling the assembly. For the throttle body temperature sensor one has to remove the air cleaner, then disconnect the wire harness connector and then unscrew the sensor to have the heat transfer compound applied each time it is fixed back. Similar to the fuel pressuriser regulator, the procedure begins by disconnecting the negative terminal of the battery, then removing the vacuum hose from the regulator. The regulator is then unscrewed and has its gasket and O-ring replaced before being reinstalled. Aqually tricky are the fuel injectors, solenoid type-to get to them, one has to clearing the air cleaner assembly, relieving fuel system pressure, and disconnecting the negative battery cable as well as removing the holder clamp and then the injector carefully but with correct alignment and ensuring that they are lubed before they are put back. The removal and installation procedures of the throttle position sensor and idle speed control actuator are the same, with the removal of the negative cable and removal of the wire harnesses, with adjustment to the idle speed control after fitting. The Manifold Absolute Pressure (MAP) sensor differs a little across the models: the vacuum hoses and electrical connectors must be disconnected, after that the sensor must be unscrewed or unclipped to be replaced. This is followed by the Single Module Engine Controller where the air cleaner duct has to be cleared, the module has to be unscrewed and the wire harness has to be disconnected before it is screwed and installed back in a reverse manner.