This post is to help others who may have this issue where you perform a throttle body alignment but it doesn't actually work. This is what happens with my car.
Every time the cars battery is disconnected it loses it's throttle body settings (this is normal) but for some reason the alignment process doesn't seem to work on my car and I always struggle to get the throttle body re-aligned which means that the cars idle fluctuates.
At traffic lights or junctions when coming to a stop the idle will drop and go very low before it jumps back up to the normal level, but sometimes it will go too low and the engine will cut out. Therefore you have to keep your foot on the accelerator to stop this from happening which is very awkward.
I've tried aligning the throttle body by leaving the key in the On position for a few minutes, and also by using VAG-COM to do the re-alignment (http://www.ross-tech.com/vag-com/cars/throttlebody.html
) but I still get the idling problem.
I found an interesting article about prerequisites to performing a throttle body alignment:
The main points are:
No DTCs in the engine controller. So clear all your fault codes!
Battery voltage at least 11.5v.
The throttle body must not be dirty (carbonised).
The coolant temperature must be between 5 and 95 degrees.
So I cleared all my fault codes, made sure my battery was above 11.5v and my coolant was above 5 degrees. I didn't really want to be taking my throttle body apart to check if it's clean or not as I knew that the previous times I had taken my battery off and tried re-aligning the throttle body it had always worked, but not straight away, generally after driving around for a few days or weeks with a large amount of fiddling with VAG-COM (but I couldn't remember exactly what I did).
So I did this and still no joy and then I found a post where one guy said he just turned his Air Con on to stop the car from cutting out at traffic lights (as by switching it on it automatically increases the idle).
This gave me an idea as I heard you can adjust the idle yourself using VAG-COM. Idle Speed Adaptation (http://www.ross-tech.com/vag-com/cars/audiB5.html
You have to Login to do this using the code 01283 to be able to set the values.
The value in the field was 128 so I tried 130 and tested it and it raised the idle. I tried revving a few times and it seemed a bit better. I then tried 132, then 124 and it seemed a lot better. I then put the value back to 128 and everything was perfect! No hunting idle, no cutting out, just back to normal. So if anyone is having this trouble try doing an Idle Speed Adaptation using the values 130, 132, 124, 126 then finally 128 and leave it there.
Hope this helps someone! Cheers.