Digifant engine management system

Digifant is the outgrowth of the Digijet fuel injection system first used on water-cooled Volkswagen A2 platform-based models.

Digifant is an engine management system designed originally to take advantage of the first generation of newly developed digital signal processing circuits.

Changes in circuit technology, design and processing speed along with evolving emissions standards, resulted in the development of new engine management systems.

These new system incorporated adaptive learning fuzzy logic, enhanced and expanded diagnostics, and the ability to meet total vehicle emissions standards.

A limited number of 1987-1990 California Golf and Jetta models are equipped with Digifant II that features an on-board diagnostics system (OBD).

This system can also have carbon monoxide (CO), ignition timing and idle speed adjusted to baseline values.

In 1991, California Golf, Jetta, Fox, Cabriolet and Corrado vehicles were equipped with expanded OBD capabilities.

Another characteristic of Digifant II equipped vehicles in California is a switch mount on the dashboard which has a "Check Engine" symbol.

Digifant I models in California feature a Check Engine light, with the display of codes done by a special Volkswagen tool under the shift boot, or by a jumper and an LED by the home mechanic.

Vehicles using engines equipped with Digifant fuel injection typically operated both efficiently and smoothly when new but suffered from a number of issues as the car aged, even by a few months.

In the 1980s and 1990s many Volkswagen / Audi designs did not incorporate sufficient engine compartment grounding, and when the car's engine compartment became soiled with dirt, oil & road salts from several months / years of use, the fuel injection system would fail in often inexplicable ways.

Later versions were improved by providing multiple grounding paths, but the early Digifant systems suffered poor service reputations.