Audi idle speed problems

Engine stalls at idle speed or stalls after the start Vehicle has no idle speed

Coking causes the piston in the idle stabilization valve -N71 to jam.

Models affected:
ABK engine from MY 95
The idle stabilization valve -N71 should be checked according to the workshop manual. If the valve sticks: Attach the modification kit for changing the air intake point for the idle stabilization valve - Part No. 048 198 455. Replace the idle stabilization valve -N71 - Part No. 048 133 455
Idle speed which is either fluctuating or excessive

The idle speed components are lacking electronic adjustment after a voltage loss in the system (for example after the disconnection of the battery, control unit change and a problem with the voltage).
Models affected:
ABK, ABC engine

Referring to the workshop manual do a basic setting with V.A.G 1551 . Throttle valve potentiometers and idle stabilization valves have been unnecessarily changed too often because of lacking system adjustment. If the complaint is not corrected with the basic setting, then a component is defective. It must be located by referring to the workshop manual.
Engine stalls sporadically when disengaging clutch after overrun/in warm weather

Current engine adjustment.
After the overrun phase (overrun cut off), the fuel injection doesn't restart in time whilst in warm weather the air conditioning compressor is switched on.
Models affected: V6, 2.6 l, 2V, ABC engine, manual gearbox with air conditioning from MY 96 Optimized engine adjustment with engine control unit
Part No. 4A0 907 473 K or 4A0 907 473 L.
From Chassis No.:
4A VN 063 250
8D VA 219 000
8G VN 006 500
1. With optimized adjustment fit engine control unit.
2. (Vehicles without traction slip control) Part No. 4A0 907 473 K
3. (Vehicles with traction slip control) Part No. 4A0 907 473 L Only vehicles of MY 96: The relay for lambda sensor heating -J278 has been fitted should be investigated. Take away the relay for lambda sensor heating -J278 (if fitted) and bridge the contacts 30 and 87 to close the circuit. Position 1 on 3 connection carrier in the plenum chamber for installation location A4 (8D). Position 1 on 6 connection carrier on the passenger side of the A pillar for installation location A6 (4A):. Position 14 on 13 connection carrier under the passenger storage box for installation location Cabriolet:. Please Note: The control unit must be coded after the installation Workshop Manual MPFI Injection and Ignition System.
Poor accelerator response or the engine stalls when in the warming up stage whilst being stationary at traffic lights for instance.

In the control unit the cold initial running set is too thin.
Models affected:
AHL engine
Part No. 3B0 907 557 A for improved control unit.
Identification on the sticker "5WP4351", data version "D05".
Wavering idle speed with cold/warm engine.

A smaller vacuum hose branches off from the crankcase ventilation, which is routed as bypass around the throttle valve. Especially in winter the throttle hose and/or the vacuum hose can become clogged and/or iced up with crankcase condense water. Consequently the idle speed wavers by several 100 rpm during the phase of warming up, gradually dying down as the engine heats up. Pulsations in the air inlet hose are possible through the crankcase ventilation.
This leads mainly to wavering idle speed with switched on electrical consumers and air conditioning with a warm engine.
Models affected: ADP engine 1.6 l
Take away the intake hose complete with crankcase ventilation hose and vacuum hose. Clean the throttle hole, 2 mm (4) diameter, and hose of the vacuum (3). Take away the cylinder head cover, put in the new oil splash guard and get rid of the old one - Part No. 06A 103 544 - (unscrewed).
Adjust the cylinder head cover and intake hose. Do not lose the O ring and make sure it doesn't lose itself in the neck of the crankcase ventilation hose. A tiny wavering of idle speed by approx. 50 rpm when the vehicle is still rolling and the clutch is pressed down is no cause for concern and is normal.
When cold or even just after more than 20 seconds or so the engine doesn't start.
There is a vehicle breakdown and no fault is stored in the fault memory.

Engine adjustment.
Models affected: ACK engine (142 kW) from MY 96
1. Look at the fault memory of the engine control unit. Investigate the vehicle according to the workshop manual if a fault has been stored.
2. See if the basic setting of the throttle valve control unit is correct, if necessary reset it.
3. If the basic setting is all right and if no fault has been stored, take out the spark plugs and clean them, then replace.
4. Part No. 4D0 907 551 B - with data version D09 - Fit control unit.