This 2.0T A3 came in for misfiring issues and some maintenance. After scanning the car there were no stored trouble codes, but is was very apparent what the car needed based off live data logging. As our mechanics started to disassemble the car to perform the carbon cleaning, the misfire issue was confirmed. A failed sticking fuel injector was forcing the car to misfire uncontrollably. So with the misfire issue found it was time to get to scrubbing. After the carbon cleaning service was done it was on to the next, the timing belt, spark plugs and coil packs were also replaced. After this work was completed we spoke with the customer and asked if the cam follower had ever been checked or replaced and our mechanic was concerned with the vehicles mileage. With the answer to that question being no, we were quite worried of what we would find.
The cam follower is a wear item that should be checked every 10-20k miles on any FSI engine depending on the modifications. This cam follower is part of the high pressure fuel pump and a key part that generates fuel pressure to the injectors. This high pressure fuel pump is a mechanical piston/plunger pump design and the cam follower rides along a designated lobe on the camshaft to actuate the pump. So, since this piece had never been inspected or changed we were worried what we might find. We pulled the pump out and there was a massive hole in the bottom of the cam follower, NOT GOOD. This piece was so worn through that it scored the cam shaft to the point of needing replacement. At this point we were quite surprised that the car didn’t not set a CEL for low fuel pressure. So the car was prepared for camshaft replacement. Before removing the camshafts our mechanic inspected the cam timing chain and discovered that there was typical slack in the chain for a vehicle with this mileage. So we recommended that while we were in this far, replacing the tensioner. With all the work completed, this A3 is now back together and running great.
Below is the carbon buildup these direct injection cars suffer from over time.
Below Right: Pictured is the worn through cam follower. Below Left: Where the fuel pump resides, you can see how the worn through follower had damaged the cam shaft
Below is the example of the damaged and score marks on the camshaft from the worn follower.