[A4] Coil Pack Help

[Pbadore at aol.com]

The ignition control module was used on AEB Audi and Passat 1.8l turbo 
engines from 1997 model year through part of the 00 model year. After that the 
function of the ignition control module was integrated into the individual coils.   
Your A4 doesn't have a nice easy to change ignition coil pack. 
The problem that you are describing seems like too rich a fuel mixture. I 
have had a problem with 
similar characteristics which was caused by having a completely refueled car 
with a full tank of gas that then was left to sit in the driveway for about a 
week. The summer sun caused enough vapor pressure to flood the engine and 
cause it to run on only 2 or 3 cylinders for a few a couple of minutes.
If your A4's coolant temperature sensor is failing it is possible that the 
engine ECU thinks the temperature is low and then overfuels the car. The coolant 
temperature sensor is easy to change
and a lot of them have failed--but usually it is only the gauge part of the 
sensor function. The next 
component that I have seen failed intermittently is the evaporative control 
valve which vents the fuel tank vapor to the engine after the engine is warmed 
up. If the valve sticks open then the vapors from the fuel tank venting will 
collect in the intake manifold and make the engine run rich. Also an oxygen 
sensor that sends a wrong signal can cause a similar problem.   And I would guess 
that a manifold pressure sensor that malfunctions indicating boost when there 
is none would do the same. I have not had an A4 do this but my 90 Corrado G60 
supercharged engine with a bad MAP sensor would completely foul out a new set 
of spark plugs in less than two minutes of running.   With a number of 
possible reasons (there are more) for rich running you need to read the fault codes 
and measuring blocks with a tool like VAG-COM otherwise you will be in the 
"cut and try " mode of repair. Lastly, how old are the spark plugs in your A4? 
Sometimes the deposit build up on spark plug electrode insulators can cause 
random misfiring when the plugs are not at their operating temperatures.
Good luck.