I own an A4 Avant 2.5 TDI 180BHP / 132kw Multitronic 216,000km fully serviced. Recently it has developed what I would describe as a lag between receiving an acceleration order and accelerating correctly, happens mainly in slow town driving i.e starting and stopping, but also when trying ¨kickdown¨. The symptom is a gradual acceleration with revs going up but the turbo doesn't kick in until it's overdue. As if the engine is holding it's breath. Any suggestions? I have an appointment for Wednesday afternoon in my Audi dealer, however he maintains that if nothing shows up on the Diagnostic computer, it may be quite tricky.????

 

yor diverter valve might be leaking. its a common thing with the stock audi ones. it is allowing air to go back to the intake and not letting spin the turbine. untill yo give it a high enough demand.

also your maf sensor may be getting the wrong voltage

and maybe your tps is not getting the right voltage

vaccum leak maybe

any of those things will do it