Club 80-90 Forums

Whats the difference between a 251 907 393 D and a 251 907 393 C VW T25 2.1 Injection Idle control units

I know ones early and ones late but will the D one work on the C system

Suffix C is for DigiJet, ie DJ
Suffix D is for Digifant, ie MV

DigiJet has a vacuum advance/retard distributor, ignition amplifier and dls shift unit to faslsely retard spark at low revs whereas all of this is done by the ECU in Digifant, and Digifant has lambda in the exhaust so the ECU controls both fuelling and timing dynamically to achieve optimum 'clean' running; Digijet controls fuelling but spark timing relies on the externals much more and without feedback from the exhaust

another old link for Digifant stuff from 2001, US based

Solving driveability problems etc.....