Common Fault: VW 1.4L TSI Piston Failures VW 1.4L TSI Twincharger CAV / CTH Engines: No Compression & Cracked Pistons All Head Services recently had a The piston issue surfaced early, There is your problem... This cylinder VW Tiguan 1.4L TSI “Twincharger” and Volkswagen started a service was missing from low compression CAVD engine sent in for a rebuild campaign (24S4) in 2010 to reduce its caused by detonation. due to low compression on number occurrence. It involved reprograming two cylinder. The engine was the ECU with recalibrated settings for dismantled for inspection, and the knock sensor. This may have been number two cylinder’s piston rings helpful; however, there was another had worn through the ring land problem that Volkswagen could not of the piston, and the other three control. pistons had cracks in the ring lands. These engines are designed to run These 1.4L TSI Twincharger engines on 95 RON unleaded petrol. RON are based on the EA111 engine family. stands for Research Octane Number They were designed on the idea of and the higher octane fuel allows “downsizing” in which a powerful and the engine to compress the air/fuel very efficiency smaller capacity engine mix to a higher compression ratio can do the same jobs as a larger less before detonation occurs. This makes efficient engine while consuming less the engine more efficient. However, fuel. In this case with a combination as you have noticed at the service from the engine. If it occurs for a of supercharging, turbocharging and station, the higher the octane rating, prolonged period, it will cause the direct fuel injection. These engines the more expensive the fuel gets. ring lands to crack, the rings will have won the award for best engine If the owners of these vehicles run break, which then start to wear their in the 1.0L to 1.4L class from 2006 the engine on 91 RON fuel because way through the ring lands (as shown to 2014 and was awarded the best it is cheaper at the pump, it will in the pictures). The first signs of this overall International Engine of the cause preignition, detonation or problem will be some rough running, Year for 2009. (See Tech Talk July 2007 pinging, which are all different then misfire related codes, but by page 2597 for system overview) names for uncontrolled combustion this time, the damage has been They are used in Volkswagen Golf, in the combustion chamber. This is done. A compression test should be Jetta, Scirocco, Tiguan, EOS, Polo and combustion which occurs too early conducted to confirm the issue. Passat. Also the Audi A3, Seat Leon which then tries to force the piston These small, high output engines and the Skoda Octavia from 2005 to back down the cylinder while it is still have been designed to perform very 2013. They have engine I.D. codes on the way up on the compression well when all of their requirements starting with CAV or CTH. However, stroke. are met. You should have a chat with trouble was coming. Uncontrolled combustion can occur your customers with these engines without any audible noise or knocking and encourage them to use 95 RON fuel, as recommended in their All of the pistons owner’s handbook. Otherwise, the had a crack in money they think they have saved the ring lands. by buying cheaper fuel, probably will not cover the cost of a rebuilt engine. We would like to thank Geoff, from All Head Services, for his technical knowledge & photos. www.allhead.com.au 4580 Tech Talk – September 2018.