salts from several months / years of use, the fuel injection system would fail in often inexplicable ways. Backfiring, stalls & other poor running were all too common. Later versions were improved by providing multiple grounding paths, but the early Digifant systems suffered poor service reputations. Most of driveability issues can be traced back to a few issues: Bad ECM earth/ground Bad o2/lambda sensor earth/ground Faulty Engine Coolant Temperature sensor (ECT) The engine coolant temperature sensor is located in the coolant flange,(under the distributor on the Polo Fox Coupe) on the front of the cylinder head (on transverse-engine vehicles). The bad earth/ground can be traced to an essential ground strap on the front upper transmission bolt. Without this, the ECU tends to earth/ground elsewhere, causing a specific trace to burn out on the circuit board and killing the ECU. This causes the injectors to stay open constantly, flooding the engine. See also Jetronic Motronic References Robert Bentley. Volkswagen GTI, Golf, Jetta Service Manual 1985 through 1992. Cambridge: Bentley Publishers, 1992. Volkswagen of America. "Digifant Engine Management". Engine Management Systems. Auburn Hills: Volkswagen Service Publications, 2006. 31–36. External links Volkswagen Group corporate website Fuel Injection theory Volkswagen Group engines Fuel injection systems Embedded systems Power control Engine technology Automotive technology tradenames