EMS Light intermittent - Air Mass Meter/breather pipe

[tusken]

I recently purchased an x reg 2001 a3 1.8 t sport, private sale.

the ems light came on the day after i bought it. it hadnt been on when i test drove it, when the rac checked it out, or when i drove it 50 miles home after i bought it. The light came on the following day.

i had it checked by the main dealer (yes, i know, mistake!) who plugged it in to vag com and said it was due to needing a new air mass meter , and a faulty breather pipe (sorry i didnt get the actual numerical codes). since this work was going to cost 300 inc labour at the dealer, i thought i would shop around.

before i got the work done, 3 days later, the light went out, and it stayed out for the next two weeks - driving it short journeys every day.

I did a 150 mile round trip this weekend - drove like a dream.
then on monday, EMS light comes back on again. it goes out again four days later - so its off at the moment

my questions are these:
1. the car drives well even when the light is on - any symptoms i should be noticing with those faults?
2. am i doing any damage to other engine parts/systems by my "lets just wait and see" method?
3. im sceptical about rushing into changing parts when the light goes on and off - reading these forums shows that it often isnt the first thing they change that fixes the EMS light problem. Any advice people can give on this? so how confident can i be that the error codes that come up, are the real problem? could it be the sensor?
4. where is the breather pipe and is it easy to change myself? (i think i can change the air mass meter/maf myself)
5. could it be anything to do with the lambda sensor?

thanks for your help in advance

[a8 tech]

Ok welcome to the broadband lambda fault.You need to get some info out of the engine control unit.DONT CLEAR THE MEMORY.The fault code is or codes will relate to bank 1 lambda multiplication lean/rich.Basically what is happening is the lambda is trying to inform the ecu that there is a unburnt fuel issue/air leak hence lean/rich.After the lambd has tryed and failed to correct this it tells the ecu its outside of its settings and the light is put on.Measured value block 32 is critical as it holds the long term fuel trim readings which will help in determining the source of the problem,this info is lost if the fault codes are cleared and may take 100 miles to record again.The light is on then off then on as this mixture problem may not be there when motorway journeys,and may be at part throttle.Theres alot to take in but basically you will have a unmetered air leak or fuel pressure issue.Are you using more fuel when light on and is the exhaust tail pipe full of black carbon,does the cat stink.Try and get the fault code and 32 readings and dont clear the memory.BEST REGARDS Jon

[tusken]

Thanks Jon for your technical help. I did wonder if it might be the lambda. However, when i took it to the main dealer, they didnt tell me there were any error codes to do with the lambda, only the air mass meter - although should i trust anything the main dealer says?

I must say when its cold in the morning, it does run very lean, it doesnt stall but i can tell the engine is labouring slightly at low revs. It only does this when totally cold - after that its fine.

So are you saying i shouldnt relace the air mass meter myself yet? i was going to do that as it didnt seem too difficult.

i guess i should try and find a friendly person with vag com in the Reading/Berks area - are there any kind souls out there?

am i right in thinking the error code can still be read, even tho the light has gone out now?

thanks for your help - and sorry for the extra questions. I really dont know a huge deal about cars - what i do know ive picked up from reading on the internet rather than any actual practical experience

Russ

[a8 tech]

Do you recall the fault code or description of the air mass meter fault.If you recently visited audi you will have a job number on your invoice,ring them and quote the number and ask for a copy of the diagnostic print out.They have to keep a copy for h.s.o audits by audi.Russ it maters not to me if you have limited experiance of repairs/diagnostics,as long as you have some common sense thats more important.The fault codes may have been erased but if you can retrive them from audi it would allow me to guide you in the right direction.I prefer to keep the technical side to a minimum as it could confuse and that wouldnt help you.Regards Jon

[tusken]

Thanks Jon - right i will ring the dealership and get a copy of the print out. i'll post back here in a week or so when i have the results