Could u be more specific - what is your car? year? model?
according to
http://www.aim-sportline.com/downloa...eng_091214.pdf
most VW supports ISO9141.
Obduino32K has ISO9141, ISO9141 slow & fast - and these slow and fast are KW1281 see
OBD KW*1281 Protokoll (KWP1281)
So first u should try as it is before asking for modifications that are needed.
Anw it would be very hard to help u if others do not have car with specific prototocol to test.