Hello,

I have a 2011 Audi Q5 (8R) with a 2.0 litre TFSI Engine. Engine code is CNDB.

The car had started experiencing and issue with loss of power, the issue seems to come and go seemingly more noticeable when its properly warmed up but not entirely sure if that's just my perception.

Under moderate acceleration the revs build up and all seems fine then they drop about 500rpm and it feels sluggish. Sometimes the revs jump back up and drop off again, sometimes they don't! Definitely feels like a boost issue.

There are no error codes.

Checks done so far are:

System scan with VCDS - no errors logged and timing chain adaptation is around 3

Cleaned MAF, spark plugs and air filter

Smoke-tested with machine and bung after MAF, a little bit of smote came out from underneath the upper timing chain cover. A bit of a concern but not convinced its the cause of this issue. Otherwise no other leaks

"Checked" the turbo actuator not sure what the correct thing to do is here and access is very limited however I could get my fingers around it and no movement could be felt in it. If the car's started it doesn't move but if revved hard I have seen it move back (towards the front of the car) and seemed to be quite smooth

Without an error code or anything obviously wrong I'm a bit lost with where to go next. Any advice on how to take this one forwards? I'm particularly interested in how to diagnose the actuator as this seems like a pretty likely suspect but I can't see an issue with it!

Checking actuator is fairly specialised. My understanding is it’s measured with a vacuum pump. If it loses pressure then it’s the actuator. Even if you can diagnose the actuator, then it needs to be calibrated to the turbo. Only had issue before and identified similar issue with Allroad 2.0 TDI. Purchased genuine Garrett turbo from turbo-diesel.co.uk. Audi were charging daft money for basically the same part. Oil feed lines need to be changed as a matter of course as union nuts often leak.

Have you also looked at HT leads? Any misfires? If you have access to live data on VCDS you might be able to run actuator. There’s a dedicated forum on Ross-Rech that you should look at and potential find answer there.

Thanks, really hoping I can track it back to something simple now!

Ross-Tech looks like a good forum sill have a look on there.

Coils were all replaced around 18 months ago. It isn't showing any misfire codes and doesn't feel like a missfire as still runs smoothly when the power fades. I do have a couple of the old, good coils that I can try swapping in to see if they make a difference.

Any other ideas for easy things to check are welcome!