A8 3.0 DTI 2005 - loss of power - advise requested

[jamesc69]

I wonder if anyone of you guys can advise me.

In recent weeks the check engine light has come on. However it has always cleared itself before I could get the car to a garage. When the light was on the car appeared to run perfectly OK.

However yesterday the car idled ok, and ran ok on light throttle, but had no performance whatsover. No audible whosh of the turbo, unable to rev above 3,000 rpm (unless i held gears on tiptronic).
No warning lights were showing.

I left the car overnight, and the following morning the fault cleared. Full performance, turbo spinning freely.

This morning eveything was ok. However on returning to the car after some shopping again the car has no perfromance whatsover. Again no warning lights.

Any suggestions and advise is much apprecated.

James

[jamesc69]

thanks for the help guys.
I got the car scanned which returned code P0046 (Solenoid on turbo?).
However since the car was scanned the fault appears to have gone and stayed away.
I propose to wait and see if fault re-occurs. If it does I will take it to a speclialist.
thanks again
James

[jamesc69]

_Batty_ said:

jamesc69 said:

thanks for the help guys.
I got the car scanned which returned code P0046 (Solenoid on turbo?).
However since the car was scanned the fault appears to have gone and stayed away.
I propose to wait and see if fault re-occurs. If it does I will take it to a speclialist.
thanks again
James

if its not the solenoid it will be the turbo. a new one is £1200 and audi charge 1600 to fit.
a specialist will charge 1400 if you haggle.
i know as our A6 Allroads turbo just failed at 56k.
very unhappy tbh.

Bloody hell I hope its not the turbo ! Did you notice anything unusual on your Allroad before the turbo failed. Unusual noises, turbo bearing noises, varying performance etc?

Mine seems to be running perfectly (except when in limp home !) with no worrying noises?
However car does smoke somewhat when booted.

[jamesc69]

Batty and Tame Technician were right. Knackered turbo has been diagnosed. (Well sticking manifold / wastegate??)
Audi main agent price £1200 + VAT for turbo and £400 odd to fit.
I am going to try a local specialist who has been highly recommended by my local garage.
New turbo direct from Garrett £700 + VAT and approx £150 to fit. Sounds a lot better.

As a mentioned before the car was remapped 10 months ago. The guy at Garrett suggestedd the remap would not have helped turbo life. Perhaps this might be a warning to those thinking of getting their cars remapped.

My car has only done 60k miles by the way. Not happy!!!

[jamesc69]

I seem to be getting some conflicting advice. Is Tame Technician about??

The turbo supplier (AR Turbo Engineering Ltd) suggest the vacuum solenoid valve, and the boost pressure sensor should be changed before replacing the turbo.

However two local specialised disagree and say the problem will in all likelihood be a overboast due to carbon build up so the turbo vanes and will need replacing anyway.

Confussed? I am !

Any advice much appreciated.

James

[jamesc69]

Tame Technician said:

The vacuum solenoid or N75 isnt fitted to that car IIRC. Is it not a black box (electrically controlled) turbo?? For the fault of overboost is will never be N75 even if its got one, that would cause under boost.

Often Garages will change the boost pressure sensor first as is say £50 when a turbo is £1200. The fault you have could technically be generated by a faulty boost pressure sensor, falsely reporting the boost pressure too high when infact it isnt. But this is very rare indeed. Turbos failing in this way isnt.

You did get someone to diagnose this, rather than just reading the posts on here right??? I Work on Audi's every day, and know what I'm doing and have seen before many times, but without actually touching and testing the car properly I would risk the cost of a turbo.

Yes car has been scanned and returned fault code P0046. The garage did not mention the boost pressure switch just that the turbo will probably need replacing. I suppose I am a little concerned that the garage would prefer a £1200 turbo replacement job rather that a £100 sensor job. A little cynical of me i know but there you go!