A6 Misfiring

[enda1]

Need some help/advice. My '99 A6 1.8T has developed a misfire and loss of power above 5K revs. The car has 67K on the clock. It's recently been serviced and all Audi parts were used. I don't have access to VAG.COM but I have a OBD11 scan tool and this is showing no faults. Before I bring it to the dealer to get the diagnostics checked is there anything obvious such as
1) Coil packs do they fail and can I check them with a multimeter
2) Fuel filter, how often does this need replacing
3) MAF, I know my brothers passat diesel has problems with these but are the petrol ones more reliable.

If there is anything I am missing, if so help would be appreciated.

 

[S4_dan]

leads and plugs? My dad had his car serviced with new leads and plugs etc, then driving under load / putting foot down car began to misfire....problem? A spark plug had cracked!

Simple repair but costly to trace as the garage searched for it. was too cold and wet for my old man to b bothered and have a look himself!

 

[enda1]

Thanks for the reply Dan. I changed the plugs but the problem is the same before and after the change

 

[dummi]

coil packs and maf are quite common problems on petrol engines

if you need any new VAG parts try www.vagparts.com , cheap than your local stealer

 

[HNH5]

an easy way to see if the MAF has died is to drive the car with the sensor unplugged - if it's the same with the sensor unplugged then you can be almost sure it needs replacing.

 

[enda1]

I used a CTools scanner check the engine faults. i got the following code
"45AA Tank Breathing Valve-N80 Open circuit". Anyone know where this valve is and how easy is ti to access