Hello,

 

For the past 4 months I've been driving a 2011 1.6 TDI DSG Polo 6R, 90hp. In this period of time I changed all filters, oil (engine, power steering, brakes, transmission), and a few other components that failed in the meantime.

Recently I noticed a weird behaviour with the engine at idle. I managed to catch it on video this time. With the car in park/neutral/drive with the foot on the brake, engine revs jumping up and down as shown in the video. This happened after 5 minutes of driving. In adition, when this is happening, there is white-ish smoke coming from the exhaust, not that much that I can't see behind but enough to make it hard to see. Unfortunately because I am a beginner, I am not able to identify what type of smoke it is. After driving slowly for a bit, sometimes at idle it will stop revving up and down but it will stay at 980 RPM at idle, usually it stays at 910-920 and the engine will run and sound poorly.

 

From what I could find online, many results point at a vacuum leak, O2 sensor or idle air control valve.

 

Has anyone seen this behaviour before? I am trying to narrow down the possibilities as much as possible.

 

 

Thank you for your time

Edited 27 November, 20232 yr by Bogdanpolo

maybe check the intake temperature sensor or the manifold pressure sensor, if its giving false readings the car can have problems setting idle. buy and obd scanner and check the readings