VW Touareg Misfire Fix: Common Ignition System Issues

I experienced something very similar with my 2005 VW Passat. As someone with moderate experience working on VWs, those symptoms immediately point toward fuel delivery issues. My car showed identical problems, rough idle, cylinder misfire, and jerking during acceleration. After diagnostic testing, it turned out one fuel injector was defective, causing irregular fuel spray patterns and incomplete combustion. The repair involved: Complete testing of all fuel injectors, Replacing the faulty injector unit, Cleaning the remaining injectors, Basic recalibration of the fuel system Total cost was 515€ including parts and labor. Since the repair, the engine has run smoothly with no misfires or power issues. Before jumping to conclusions though, could you share: Current mileage on your Touareg? When was the last time spark plugs were replaced? Are you getting any specific error codes? Does the problem get worse with higher engine load? This information would help determine if you are dealing with a fuel injector issue like mine or possibly something else in the ignition system.

Thanks for the detailed advice. My Touareg has 138077km on the odometer. The spark plugs were actually replaced during the last service about 8000km ago, but no work was done on the fuel injectors at that time. The engine misfiring definitely gets worse under load, especially when climbing hills or during hard acceleration. The check engine light started flashing recently when the problem occurs. After reading about your experience with the fuel injectors, I am thinking this could be the root cause of my issues too, as the symptoms match up pretty closely. I will have the fuel injectors tested and cleaned as a first step. If that does not resolve the combustion misfire, I will look into having them replaced.

Thanks for the follow-up. After fixing my Passat injector issue, I actually encountered similar symptoms again about 15000km later. This time the misfiring under load and flashing check engine light pointed to failing ignition coils, not the injectors. Had all ignition coils tested and found two were deteriorating. The workshop replaced all coils as a preventive measure since they tend to fail around the same time. Also had them check the spark plugs, despite being relatively new, one was showing signs of carbon fouling. The complete repair included: New set of ignition coils, Spark plug replacement, Computer system reset Total cost was 380€ and completely solved the rough running and misfiring. Worth checking both the fuel and ignition systems since symptoms can be very similar. The flashing check engine light specifically suggests combustion misfire, which can be caused by either system. When your spark plugs were replaced, did they also inspect the ignition coils? They often get overlooked during routine service but are a common failure point on these engines.

Thanks for the detailed information about your experience with the ignition coils. This actually matches what happened when I took the car to my mechanic yesterday. They found that while the fuel injectors were working fine, two of the ignition coils had indeed failed their testing. Like in your case, they recommended replacing the full set rather than just the bad ones. The throttle response is much better now after replacing all the coils and I have not seen the check engine light come back on. They also cleaned and checked all the spark plugs while they had everything apart, luckily those were still in good condition from the recent service. Total repair came to 365€ which seems reasonable compared to what you paid. The rough idle is completely gone and the engine pulls strong again with no misfiring. Really glad I checked the ignition system rather than jumping straight to replacing injectors. Thank you for sharing your similar experience, it helped confirm I was on the right track with the diagnosis.