Q3 2013 TFSi Petrol Engine Misfiring

[Paulo71]

Hello I have a Q3 TFSI 2013 PETROL MODEL.  I have bought this from a garage in August and on one occasion I noticed that the car was juddering on the motorway.  I took it to a trusted mechanic and they ran diagnostics and detected one spark plug and coil needed to be replaced.  This seemed to resolve the issue.  Six weeks later the vehicle was used for a 60 mile round trip and the same problem started to occur on the motorway.  The vehicle was shuddering and losing power and then the cabin started to fill with petrol fumes.  I limped home and took it into Halfords Autocentre.  They look at the engine and reported that all the spark plugs required replacing and the the chambers were full of fuel.  This resolved the problem and then I have been using the car for 2 months.  A few days ago on another 150 mile roundtrip and the car has started again misfiring and a strong smell of petrol fumes.  This repetition of the same fault does not bode well and the car does not have alot of mileage since we bought it.  57,000 in jULY and 59000 now.  Any help on what the problem is, the action/repair required and likely cost?  This would be appreciated

[Magnet]

Hello Paul,

Thanks for being in touch. 

I would not like to claim this is the answer to your issues, but it could be that the car is overfueling/ running too rich and contaminating the plugs, rather than faulty plugs or coil packs. 

Does the car use any significant amount of oil? 

If it were mine, I think I would be considering a simply emissions test at your friendly local MOT station. 

Kind regards,

Gareth.