Jols

Hi, My 1997 A8 4.2 Quattro with the ABZ engine continually wants to stall when I slow down from high speed.
It is fine when I slow down in traffic, but usually suffers froma lumpy idle and sits just above 600 rpm.
On start up it is fine (cold). This only happens when it has warmed up.
It rarely does stall, but the battery light flicks on, but it recovers.
If I coast down from speed, then it is fine.
This happens in both normal auto AND Tiptronic mode.

I have replaced the spark plugs, air filter (standard filter - will change it for a K & N), and will also clean the MAF.
Any other advice will greatly help.

Regards

PaulW

If so...what are they? If not, you need to pull the codes.

I have never heard of an ABZ engine stalling, but it does sound like a bad/dirty idle control valve...the thing that controls how much air is sent to the engine during idle...it is pulsed with 12 VDC by the ECU during idle conditions...

Or you could have an air leak on your air hoses between the air filter and engine.

Jols

OK, I do not have a VAG-COM system to pull the codes.
I have had the air hoses off various times (cam cover gaskets, air filter etc etc) and it has not changed.
Where is the Idle Control hidden, see if I can clean it at all.

Thank You!!!

PaulW

It's the silver piece in the picture to the right of the red box.....it is called Idle Air Control (IAC) valve -N71-, the piece furthest back in the engine bay against the fire wall.

<img src="http://www.audipages.com/Tech_Articles/enginemechanical/SP4.jpg">

It bypasses air via a solenoid inside that is pulsed with 12 VDC based on required duty cycle of the engine to maintain speed.

A lot of Audi's in the past had these valve gunk up and no longer were free mechanically and could not open/close fast enough to maintain proper airflow. Clean it with some brake cleaner and see what happens.

If you work on your own car (even if you don't) do yourself a favor and buy the ross-tech software and the Bently, the best $300 you'll ever spend, it makes my life easier too! ;-)

Jols

Thank you. Will try that this coming weekend. The car has go 180,000 miles (UK), so it might well be gunked up.

Will let you know if this has worked.

QuattroMarko

Hi:
Yours is an older post about your A8 stalling-did you ever get to the bottom of it-I'm having same issues with my 98' when decelerating -Thanks-