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Motor control Digifant II DF-1

Digifant is the name for an engine control unit series of the Volkswagen Group. The made-up word Digifant is made up of “digital injection” and “white elephant”. The Digifant is a further development of the Digijet and the ignition system (Dignition) and combines both individual systems into one engine control unit. The aim of this summary was to obtain the lowest possible emissions and economical consumption with optimal performance. It has been continuously developed, with additional functions being added or changed depending on the engine type and year of manufacture. The Digifant was finally replaced by the successor system Simos .


The Digifant is an electronically controlled injection system with programmed maps for injection time and ignition point. It has overrun fuel cut-off, lambda control, cold start, warm-up and full load enrichment. Depending on the type, the injection valves are activated simultaneously or sequentially and inject the fuel into the intake manifold in front of the intake valves. The ignition point is determined electronically in all Digifant variants. Most Digifant variants have electronic idle control with the aid of an idle actuator and knock detection with one or two knock sensors.

Mixture correction

Starter detection

The control unit recognizes the start of the engine. The switching of the fuel pump relay is ensured by the voltage signal in the event of a voltage drop in the battery. Digifant versions with sequential injection require two crankshaft revolutions when starting to detect the TDC of the first cylinder and only then cycle the injection valves.

Cold start

The injection valves are opened longer by the control unit in order to enrich the mixture. The opening time decreases as the cooling water temperature rises. The lambda control is deactivated. The idle is increased by the idle actuator.

Warm-up phase

In the warm-up phase, the idling is stabilized by the idling actuator. The lambda control is switched on from a certain cooling water temperature.

Load changes

The throttle valve switch and / or the throttle valve potentiometer send the idling or full load information to the control unit, which changes the injection time depending on the position of the air flow meter or the vacuum or pressure sensor in the control unit.

Change in intake air temperature

Detection via the intake air temperature resistance. The control unit responds by lengthening or shortening the injection time.

Speed ​​limitation

The control unit receives the speed information from the Hall sender in the distributor or from the Hall sender on the crankshaft and reduces the injection time between 6400 min −1 and 6500 min −1 . The water boxer engines this is already happening at 5400 min -1 .

Fuel cut-off

Detection via speed and throttle valve position; the control device stops the injection engine at operating temperature, wherein the accelerator pedal released and above 1500 min -1 .

Full load

Detection via speed and throttle valve position; the control unit also increases the opening time of the injection valves.

Lambda control

A lambda probe detects a rich or lean mixture, and the injection time is changed accordingly.

Ignition timing

The engine control unit uses the cooling water temperature, engine speed, load status and, if available, the knock sensor (s) to adjust the ignition timing. The idling is also stabilized via the ignition point.


The Digifant variants are very different. Due to constant further development, new functions were added or changed. The first Digifant variants had a baffle flap air flow meter, an additional air slide, a throttle flap switch and injected fuel simultaneously. There were also Digifant variants with or without lambda control, which found their way into all variants a short time later. Knock detection with one or two knock sensors and idling control via an idling actuator were later integrated. In a smooth transition, the air flow meter for airflow flaps was replaced by a vacuum or pressure transmitter in the control unit and the throttle valve switch by a throttle valve potentiometer with or without an idle switch. The newer Digifant variants inject sequentially, are adaptive, so that the CO value and the idle speed no longer have to be set, and they cushion load shocks via the idle actuator. They also have various signal inputs and outputs for engine speed, speed and consumption information, idling speed increase, automatic transmission and immobilizers. Almost all Digifant variants can be diagnosed. Some newer ones have to be relearned when changing the throttle valve potentiometer or the idle switch (a so-called throttle valve basic setting). The Digifant was installed in almost all models of the Volkswagen Group from 1985 to 2005, but also in the Group's subsidiaries Audi and Seat.

Overview of the Digifant variants

model Displacement design type Cyl. kW / PS MKB construction time
2.1 l 2081 cc WBX 4th 70/95 MV 1985-1992
2.1 l 2081 cc WBX 4th 64/87 SR 1986-1992
1.3 l 1272 cc line 4th 85/115 PY 1986-1994
1.3 l 1272 cc line 4th 55/75 3F 1990-1994
1.8 l 1781 cc line 4th 77/105 RV 1987-1991
1.8 l 1781 cc line 4th 79/107 PF 1987-1991
1.8 l 1781 cc line 4th 82/112 PB 1987-1991
1.8 l 1781 cc line 4th 72/98 2H 1988-1993
1.8 l 1781 cc line 4th 72/98 1P 1988-1991
1.8 l 1763 cc line 4th 118/160 1H 1988-1989
1.8 l 1781 cc line 4th 118/160 PG 1988-1993
2.1 l 2081 cc WBX 4th 68/92 SS 1989-1992
1.8 l 1781 cc line 4th 154/210 3G 1989
2.0 l 1984 cc line 4th 85/115 2E 1990-1996
2.5 l 2461 cc line 5 81/110 AAF 1990-1993
2.0 l 1968 cc line 4th 62/84 AAC 1990-2003
2.0 l 1984 cc line 4th 85/115 ABK 1991-1998
2.0 l 1984 cc line 4th 110/150 ABF 1992-1999
1.6 l 1584 cc boxer 4th 34/46 ACD 1992-2003
1.8 l 1781 cc line 4th 66/90 ADD 1993-2005
2.5 l 2461 cc line 5 81/110 ACU 1993-1996
1.8 l 1781 cc line 4th 95/129 ADL 1994-1996

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