You dirty MAF
 

I noticed some error codes on a recent scan for the mass airflow meter (MAF) and also the lambda sensors downstream. This was coupled with some hesitation on idle after starting, which cleared after 20-30 seconds or so.

I removed the air filter box cover and air filter and assumed the electrical gubbins at the bottom was the MAF but then realised it's located in the top part. A quick dousing with electrical contact cleaner and a 10 minute drying out in the sunshine and I put it all back together. Car starts perfectly and on a quick test run, it just seems smoother on the auto gearbox changes as well as being slightly more peppy.

(Note - I didn't remove the MAF from within the round plastic part as that seems to be secured with two Torx-headed bolts, but these aren't normal Torx, and they're not even M&S bolts... lol. The heads look like they have a little raised spot in the middle, in an effort to stop people fiddling/cleaning it properly/removing it. Perhaps this is AudiTorx, mmmmm.)

The MAF sensor is typically held in place by security bolts, which have a raised "pimple" in the centre.
Then, just to make life difficult, it's often a non-standard tip, such as 5 points, as well.

But MAFs are normally supplied in the housing (with end covers) anyway, it helps protect them and keep them clean, and being just bits of plastic the price difference is negligible.

They are indeed security Torx heads, and are meant for exactly what you say... to stop people fiddling. I've found them more often in electrical items rather than cars.

You learn something new every day...
 

Thanks chaps for the input.

I've learnt that there are indeed 'Security Torx' bits available, although my problem is now sorted. Ironically, I was just watching a YouTube video for a dirty MAF on a Mk1 Focus C-Max and the car in question had the very same security bolts on the housing.

I'm hoping that my quick fix on the Audi stays permanent, and I'm going to attempt the same cleaing operation on my friend's car - similar MAF issues.

Update
 

Pleased to report that the cleaning operation on my dirty MAF seems to be working well. No further codes and the car starts beautifully. I had my father in the car with me when a traffic light challenger rolled up next to me, and stopped the usual half a yard in front of other cars... whilst edging forward anticipating the change from red to green. Half throttle was used to get the old barge up to speed and my challenger retreated swiftly, followed by my father saying 'Crikey!'.

I think the change in performance could be partly of a psychological nature but there's definitely a marked difference in terms of responsiveness and the gearbox seems smoother too. Very happy chappy with my cheap and quick fix, which took 10-15 minutes. :love:

Well done JQ, glad to hear you're having some fun in her again +++

Indeed, the love has returned. I was thinking of selling due to my recent problems with the fuel pump/fuel tank as I'd spent over a grand and it's still not fixed since it runs out of petrol at the 3rd segment mark on my fuel gauge. I was looking at a more recent A5 sport quattro but changed my mind after seeing both vehicles at the same time whilst parked up. You just cannot compare the two, in my opinion. The D2 is such a classic design. I just keep the old girl filled up now.

Cheers, and see you later Ron :)