Recently a client presented their lovely Audi TT to us with an engine misfire.
After we performed a compression test and a cylinder leak-down test it was conclusive that the fourth cylinder was virtually inoperative and sitting at 90% leak-down. Up to 15% is considered within normal specification.
The cylinder bore was then inspected using a laparoscope to determine its condition, and mild scoring damage was found.
Our Pace technicians also removed the engine from the vehicle in order to strip it down. This revealed the fourth piston had suffered catastrophic failure in the ring land area, breaking apart the compression rings, oil control ring and piston itself.
However, the engine cylinder bore had only suffered minor damage, so all four cylinders were re-honed. The engine was then rebuilt with all new pistons, new bearings, and all gasket and seals were replaced.
The cause of this type of failure is difficult to pinpoint. However, the most likely cause is detonation, a nasty effect from the fuel burning unevenly in the combustion chamber, a result of running on regular 91 RON fuel.
We recommend always using 98 RON or 95RON at the very least for all German cars in order to maintain optimum standards.
The engine is now in new condition and running beautifully. It will be good for several thousand kms and many years to come. The total cost was around $14,000 saving the client thousands in the process.
If your vehicle is experiencing any issues, contact the team at Pace for an Audi repair or diagnostic service.