VW Jetta TDI Engine Misfires and Jerks During Acceleration

Had a very similar issue with my 2014 VW Passat TDI last year. The symptoms you describe match exactly what I experienced, uneven running, jerking during acceleration, and check engine light. After some troubleshooting, my mechanic found a leak in the exhaust system that was causing irregular engine performance. The repair involved replacing a damaged section of the exhaust and cost 265€. The jerking completely stopped after the fix. However, these symptoms could have multiple causes in TDI engines. Definitely worth checking: Exhaust system for visible leaks or damage, Fuel injector condition, Crankshaft sensor readings, Engine misfire patterns Could you share: The error codes stored? Any unusual sounds from the exhaust? Does it smoke more than usual? When was the last timing belt service? This would help narrow down if your issue matches what I experienced or if its something different. TDI engines can be tricky to diagnose without complete information. Level of expertise: Some experience with diesel engines and basic maintenance, but complex repairs are best left to professionals.

Thanks for your detailed response. The error codes stored are P0234 and P0299, which point toward a possible turbocharger issue. No unusual sounds from the exhaust and no excessive smoke. My last service was at 72000km where they did a routine inspection and oil change. After running additional tests, I noticed the engine misfire becomes more pronounced during cold starts, and there is a rough idle even after the engine warms up. I think this rules out the timing belt since it was replaced during the 60000km service. Looking at the symptoms you described with your Passat, my situation seems different since the trouble codes specifically indicate boost pressure problems rather than an exhaust leak. Would a faulty crankshaft sensor cause these specific error codes?

Thanks for the additional details. The error codes P0234 and P0299 definitely point to a different issue than what I experienced with my Passat TDI. These codes specifically indicate turbocharger over-boost and under-boost conditions. While engine misfire symptoms can be similar, the root cause here is likely turbo-related rather than the exhaust leak I dealt with. In my case, the rough idle cleared up immediately after the exhaust repair. Your persistent rough idle, even when warm, suggests a different problem. The timing belt being recently serviced is good news and rules that out. The crankshaft sensor typically throws different error codes, so that is likely not your culprit. Based on my experience with these TDI engines, you might be looking at: Wastegate actuator malfunction, Boost pressure sensor failure, Clogged air filter affecting turbo performance, Vacuum line leaks When my Passat had a similar over-boost issue years before the exhaust problem, it turned out to be a failing wastegate actuator. The repair cost was around 450€ including parts and labor. Have you noticed any drop in power under heavy acceleration? This could help confirm if the turbo is the main issue rather than an ignition coil or fuel system problem.

The turbo issues you mentioned make a lot of sense given my symptoms. Yes, I have noticed significant power loss during heavy acceleration, especially above 3000 RPM. The rough idle and turbo-related codes combined with the power loss really point toward the wastegate actuator being the likely culprit. I checked the vacuum lines this morning and found no obvious leaks. The air filter was replaced during the last service, so that should be fine. Given the similar experience you had with your wastegate actuator repair, I will schedule an appointment with my mechanic to have the turbo system thoroughly checked. The 450€ repair cost you mentioned helps set my expectations. Much better than having to replace fuel injectors or dealing with more serious engine problems. Hopefully the fix will resolve both the rough idle and the acceleration issues. Thanks for helping me narrow down the problem. Will update once I get it diagnosed and repaired.