idle & throttle-up fault...ecu?

[minky spiro]

i have a 1996 A4 avant. last week engine suddenly started shuddering at idle. initial thought was engine misfiring. mechanic investigated and changed coil to cyl 3 but no change. complete diagnostics today, no engine management fault light, ecu showing minor comms error but unable to rectify idle and throttle up fault....any ideas? thanks:confused:

[audimad]

What engine 1.8t?
If so try the ingition module on top of the airbox

[minky spiro]

cheers audimad...yes, it is 1.8T engine. being a complete novice, is this a big job or can a generic mechanic do it???

[mluton]

Does it do it all the time or was this a one off ?

[Crasher]

It is easy to change; it is right on top of the air box. They are very failure prone, especially the earlier one used up until the middle of June 97. The part number on yours should be 4D0 905 351 and they cost £201.96 from Audi but are available from other sources such as Bosch and Beru so you should be able to buy the part from GSF or Euro.

[minky spiro]

Does it do it all the time or was this a one off ?
car shudders all the time at idle and seems to get batter as revs applied...

[Crasher]

What fault codes were stored on the ECU? I know you say they were minor but I would like to know.