Boost Control:

The G-Charger (G-Lader) produces more boost than the engine can efficiently use. Excess boost pressure is controlled by a mechanically operated boost control valve and the idle stabilizer.

The mechanical boost control valve is bolted to the throttle valve housing and operated by the throttle linkage. The boost control valve moves in the opposite direction of the throttle valve. As the throttle valves opens, the boost control valves closes.

The mechanical boost control valve is open idle and part throttle. This directs the majority of the boost pressure back into the intake side of the G-Charger.

The mechanical boost control valve closes approx. 5 degrees before full throttle. This directs boost pressure direct into the intake manifold for maximum engine performance.

The boost control valve linkage is located on the underside of the throttle housing and is adjusted at the factory.  Before making any attempts to re-adjust the linkage consult an expert.

Boost pressure in excess of 0.8 bar is controlled by the idle stabilizer. The idle stabilizer will open when the intake manifold pressure is above 0.8 bar and vent the excess boost pressure to the intake side of the G-Charger.

G-Charger Lubrication:

The G-Charger is supplied oil lubrication from the back of the cylinder head. The oil pressure needed to properly lubricate the G-Charger is approx. 0.3 bar.

The oil pressure to the G-Charger is regulated by the length and inside diameter of the oil supply line. The length is 750mm and the inside diameter is 0.9 mm.

Oil is returned to the engine crankcase via an oil return line. The return line is attached to the bottom of the G-Charger and the engine crankcase near the oil filter housing.

Intercooler:

The intercooler is used to cool heated, pressurized air from the G-Charger. The intercooler is located below the left headlight.

The heated air is directed through cooling tubes with cooling fins. The Intercooler is capable of cooling the heated air from the G-Charger as much as 100 degree Fahrenheit. This increases the air density which boosts the engine's output and at the same time reduces knock sensitivity.

Digifant Engine Management System:

The Corrado G60 uses the Digifant Engine Management System. The fuel system is similar to the Digifant II System. The air flow sensor has been eliminated. A manifold pressure sensor is used to sense engine load.

Idle Stabilizer:

The Idle Stabilizer is a piston-type. The piston slides in a cylinder with two ports. With the ignition off, the piston completely closes off the ports.

When the engine is running, the piston is pulled toward the idle stabilizer motor to regulate idle speed. The current used to operate the idle stabilizer motor is similar to the Digifant II System.

CO Potentiometer:

A Potentiometer is used to adjust the CO mixture. The Potentiometer is located on the intake air duct before the throttle housing. A tamper-proof plug is used to prevent adjustments by non-service personnel.

An air temperature sensor is located within the potentiometer housing. The air temperature sensor is used to calculate air density.

Manifold Pressure Sensor:

A manifold pressure sensor located inside the ECU replaces the air flow meter. The pressure sensor is used to measure manifold pressure. This measurement is used by the ECU to determine engine load and manifold (boost) pressure.

A vacuum line from the intake manifold to transmit the manifold pressure signal. The ECU converts this pneumatic signal into an electrical signal. This signal, along with the engine rpm and intake temperature, is used to calculate fuel injection quantity.

The length of the vacuum line is 1 Meter (39 inches). The length of the hose is important. If altered, poor engine performance could result.

The manifold pressure sensor consists of a crystal chip and two semi-conductors. The crystal is shaped in such way that, when mounted on a base plate, it taps a small amount of air between the base plate and the chip.

The air under the chip allows the chip to flex when pressure is applied. The two semi-conductors attached to the top of the chip sense the flexing of the chip.

The flexing of the chip causes the semi-conductors to alter their shape. This changes the resistance values of the semi-conductors. The change of resistance values is used by the ECU to determine the amount of manifold pressure.

Knock Sensor:

The Knock Sensor is attached to a casting hole plug on the left side of the engine block next to cylinder #2.

The reason for the relocation of the knock sensor, when compared to other 1.8 liter engines, is due to a resonance that is produced by the G-Charger which could affect the knock sensor operation.

Knock sensor regulation is basically the same as the Digifant II system used on the Golf and Jetta.

If an ignition knock is detected, the ignition timing is retarded by 3 degrees for the cylinder affected. The ignition timing can be retarded as much as 12 degrees to reduce ignition knock. The maximum difference between two cylinders is 9 degree.

If an ignition knock is still detected and the ignition timing is retarded to the maximum of 12 degrees, the Digifant ECU will select a lower boost pressure curve to reduce ignition knock.

The boost pressure is reduced by opening the idle stabilizer valve and venting the boost pressure to the intake side of the G-Charger.

The ignition timing is then advanced in 0.33 degree increments. Ignition knock is then controlled by the lowered boost pressure.

If ignition knock is no longer detected and the ignition timing has returned to its normal map boost pressure is returned to its normal curve.