A4 2.0 TFSI Turbo Problem?

[ds77]

Hi everyone - I'm new here so please go easy on me! I'm wondering if anyone can shed any light on a problem I'm having with a 2007 A4 2.0 TFSI (50,000m)
Problem is that the power delivery is erratic and the turbo seems inconsistant. When I put my foot down the acceleration generally feels slower than it should until 4500 - 5000 rpm and then there is a sudden kick of power as if the turbo has just started working. The rpm at which the turbo kicks in can vary and occasionally it works as it should with a nice smooth power delivery up to red line. It feels to me like a valve or something is sticking and not working when it should all the time..
Anyway, the car is new to me, only had it a couple of weeks and bought it from a VW audi specialist with 3 month warranty. They had a look at it today and acknowledged that the power delivery was not normal but had no idea why.. There were no ECU fault codes and no engine warning lights. They checked all the hoses for leaks and also did a real time turbo check with the engine running and while driving. Didn't think anything was wrong. He thought the previous owner mainly used the car for town driving and that the variable geometry vanes on the turbo could be a bit sticky from carbon build up and suggested using a turbo cleaner and 'exercising' the turbo to try and free them up. If this doesn't work I can take it back for further investigation.

Anyone got any other thoughts? Any recommendations for a product to clean out the turbo?

Thanks for reading.

[ds77]

Looking online - does the 2.0 TFSI even have a variable vane turbo...? I think its standard isn't it?

[Roonster]

The diverter valves are extremely prone to failing. About 60quid from Audi and easy to fit.

[ds77]

Cheers. Got one ordered and in the post. Garage tried to convince me it wouldn't be this but after doing some research on the web it seems the DV can be failing without logging a fault in the ECU.


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[ds77]

Just to conclude this thread - changed the diverter valve and problem solved. The change in performance is very noticeable - full turbo boost now throughout the whole rev range.. Old valve didn't show any signs of being defective - no splits in the rubber but was obviously sticking. If you are having this problem change the DV!


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[zollaf]

did you fit a standard one or a proper one like a forge... ?

[ds77]

did you fit a standard one or a proper one like a forge... ?

Was the standard latest one. Think the one I took off was probably the original (9 years old). Had the rubber diaphragm so was the old design.