Audi Repair: Audi A3 1.6SE (2001), crankcase breather hose, sized holes

Question

Hi Jan,

Hoping you can offer some advice about 2 problems i am having with my A3 although i suspect both problems are related.

1st problem:- before Christmas dealers replaced the maf on my A3 because i kept getting the check engine light and the abs light flashing up on the dash. There was no change so i decided to look into the problem myself. Various places suggested replacing the air filter which i did and the problem went away for a month or so.
Stupidly (i now realise) i used super unleaded (reasoning that the engine could probably use the extra cleaning additives after having a dirty air filter fitted for so long). I suspect it was at this point my crankcase breather hose split because i could smell petrol when standing at the lights. When i repaired this the old MAF problem came back. I have managed to determine now when the problem occurs. The fault happens when decelerating in gear with speed under 30 mph going downhill, the error code i get relates to the air mass meter making an implausible calculation crosscheck ( i forget the actual error code & message but i can get the info if you really need it).After extensive searching i have found 3 pinprick sized holes on the piece of engine tubing after the maf near where it tees of to the oil filler/crankcase breather hose.

Do you think this may be the problem or is the MAF likely to be gash even though it's new?

2nd problem:- i think this is probably related to the first, when starting, hot or cold the engine starts normally then sometimes within seconds it starts to idle roughly for about 5 seconds before resuming normally. sometimes there appears to be an oily puff of petrol out the exhaust when it finishes messing about. Any ideas?

If you can suggest something and it's simple enough i can avoid a visit to the dealers!

Thanks

Chris

Answer
If you have any holes in the inlet, this will cause weird problems.  When you decelerate, there is a vacuum in the manifold, and any leaks will cause false Oxygen to be present in the manifold which will give problems. Make sure there are no leaks in the system between the MAF and the engine.  Jan