A8 - 4.2L

How do I adjust the idle speed on an D3 A8?

Andy@Ross-Tech

Bentley manual sez: "Idling speed Not adjustable "

A8 - 4.2L

There are no engine fault codes being thrown. Also another symptom is that during a cold start, fast idle feels like it's missing(?) a wee bit - not dead smooth. Idle seems to jump between 700-600 with it being nearer to 600 in the past few weeks causing vibration. Just got my vag-com yesterday and I was really hoping to find something.

Thanks!

Andy@Ross-Tech

I'd start by checking for damaged motor mounts.

A8 - 4.2L

Everything else is dead smooth until engine speed drops to about 600 then there is a slight "lumpiness". So slight, only I the driver notices it. Plus the idle is jumping around between 750-600. If I just touch the pedal and raise the rpms above 650 it's glass smooth.

quickaudi:STFA

when's the last time that you cleaned your throttle body and did a throttle body adaptation?

A8 - 4.2L

Any threads/references in the forums relating to this procedure?

diagnosticator1

other ECUs have idle speed adjustment via adaptation channel 001. (ECU PN and firmware version dependant,) The default setting is 128, +001 increases idle speed by 10 rev/min up to 135. -001 decreases idle speed by 10 rev/min steps, minimum 125(?).

quickaudi:STFA

to do a throttle body adaptation, look up the instructions on RossTech's website

A8 - 4.2L

I got to this channel, but it does not allow me to change the default value of 128.