A6 1.9 TDI intermittant loss of power

[dougf]

I have a 1.9TDI A6 about 8 years old that has done about 70,000 miles.

It has been suffering from an intermittant loss of power for some time and no fault was been found by the local Audi dealer on a couple of occassions.

More recently, they carried out guided fault finding and decided the boost solenoid was faulty and replaced it. On road test they said the car "still has some turbo lag due to stiff turbo"

They have quoted me £1300 to replace the turbo but I have no confidence in their diagnosis and don't want to spend the money and then find it doesn't cure the problem.

Can anyone advice me whether or not it's likely to be the turbo itself, whether it could be repaired instead of replaced and is there anything I could do myself to check if it's definately the turbo.

Many thanks

[Peter D]

There are instructions in the How to Fix section for stripping and cleaning the turbo, however you need to remove the actuator and see if the vane actuator rotates without too much resistance. Regards Peter

[Clinterous]

Have a search on the forum for 'sticking turbo vanes' - this is an often discussed problem. If this is your problem, you can get some Innotec cleaner which might provide some resolution at a significant cost saving. You also need to get a fault code as more experienced forum members will be able to shed more light on the subject for you.

The code which relates to a faulty boost solenoid is usually a clue that the turbo vanes are sticking, especially after the solenoid has been replaced.

How does the car get driven - sedately? some forum members reckon a high speed motorway run to get the turbo nice and hot will help it to burn off any excess crap built up.

[Col]

some forum members reckon a high speed motorway run to get the turbo nice and hot will help it to burn off any excess crap built up.

I'm one of them.

A really good thrashing at least once a week is actually beneficial to any TDI with a VNT turbo.

[dougf]

Thanks to all for your suggestions.

I did a search on sticking turbo but don't understand these things too well and got confused by all the various possible causes. I am new to this forum and couldn't find the How to Fix it section.

The car is used mainly for local runs when it often struggles up hills and about once a month on the motorway when after a while it losses power and will only accelerate very very slowly taking ages to get back up to speed.

I don't know if the Audi garage did a diagnostic check after they had changed the solenoid - they just said I could either live with it or have the turbo replaced. Does anyone know of an independant garage with Audi diagnostic facilities in my general area ? (Tring, Herts)

The idea of a solvent clean sounds attractive - I will look into this.

Many thanks again for all the input

[mrp0ny]

you have a fantastic car there.....mine has 400K on it now, with no major work to either engine or gearbox....plus the other bits are well up to long term ownership...the comfort of the A6 and the economy and longivity of the 1.9tdi is awesome...

Mine also does the same now......if it bogs down, I just turn off the ignition, restart and thrash it a bit and then it's fine.....must get it sorted sometime though...

[bohoo]

have you had a hissing noise lately

[Marc1]

If the vanes are sticking, try this:-

http://www.innotecworld.com/images/document/Audi%20Driver.pdf

http://www.innotecworld.com/t-audidriver.aspx

It comes up on Ebay from time to time, or there's a guy on this forum - Crasher, who may be able to help you.

[mrp0ny]

thanks guys....very interesting.......I've done a lot of miles on a vegoil mix as well......but the article exactly describes the problem.......it's a bit irritating but can be fixed with a reboot of the system at the moment......but reading this I'd better get the turbo cleaned before I break it...

[paul b]

thanks guys....very interesting.......I've done a lot of miles on a vegoil mix as well......but the article exactly describes the problem.......it's a bit irritating but can be fixed with a reboot of the system at the moment......but reading this I'd better get the turbo cleaned before I break it...
My T5 van did exactly that, fine after a re-start. If you had it on a computer you may get overboost codes, I suggest you check the boost pipes (especially the intercooler pipe) first before touching the turbo.

Not sure where the intercooler pipe is on the A6 though, but one end will be in the EGR, its the other end that failed on my van.

[Marc1]

My T5 van did exactly that, fine after a re-start. If you had it on a computer you may get overboost codes, I suggest you check the boost pipes (especially the intercooler pipe) first before touching the turbo.

Not sure where the intercooler pipe is on the A6 though, but one end will be in the EGR, its the other end that failed on my van.

When you say intercooler pipe, which bit do you mean usually fails? Mine seems a bit slack at the EGR valve. Do you mean at the intercooler end or just anywhere along that line? Is this a pipe that often fails? I seem to recall seeing alot of Samco ones, wondering if that might be a better option if the fail regulary.

Sorry OP, slightly off subject, but may help a few people out, it all relates. ;)

[paul b]

When you say intercooler pipe, which bit do you mean usually fails? Mine seems a bit slack at the EGR valve. Do you mean at the intercooler end or just anywhere along that line? Is this a pipe that often fails? I seem to recall seeing alot of Samco ones, wondering if that might be a better option if the fail regulary.

Sorry OP, slightly off subject, but may help a few people out, it all relates. ;)
On my van it was slack at the intercooler end, however I believe a slack pipe/hose anywhere on that line would still cause power loss. It's a really fat pipe, cost £50 from VW for my van.

I'm not sure how often they fail, but they have metal lugs which can wear away over time. End result is they still connect, but loosely, causing a lack of power. Usually the car would smoke a bit more if this pipe was loose.

[Col]

I don't know if this is of any relevance but I've owned both a Passat and now my current A6 with the 1.9 PD TDI engine (AWX).

On the Passat (2002) the intercooler hose connections were made via the spiggot and springclip arrangement. Not very air or oil tight! I assume the earlier A6's also had this arrangement.

On my current (2005) A6 which would have had one of the last 1.9 PD engines to be fitted, the intercooler hose connections are made via good old fashioned jubilee clips and as a result are both air and oil tight!

If your having problems with the connections, it might be worth investigating the possibility of fitting the later / or jubilee clip hoses.

I'm very pleased my car does not have those spiggot and spring clip connectors to the I/C. There are one or two on the upper hoses (I'll need to have a good look) that still use the springclips though.

[Clinterous]

Should the large pipe joins going around back of the engine to the EGR be a tight seal, or is some slack acceptable?

[Marc1]

Cheers paul b and BigCol that all makes sense. Both rubber pipes on the intercooler line have some slack in them (EGR side leaks oil too), so I've just ordered both. £15 for the EGR side and £35 for the intercooler side.

I'll be using jubilee clips if they don't come supplied (I can't remember the fitting, but mies the last PD engine too).

Interestingly enough as I changed my main beam bulbs yesterday, I got a good chance to inspect the pipe at the intercooler side, which low and behold is rather perished. With a inch split (doesn't look to be all the way through, but certainly on it's way out).

Smoking more than usual too. So thanks all, and hope this all helps everyone else. :biglaugh:

[paul b]

I don't know if this is of any relevance but I've owned both a Passat and now my current A6 with the 1.9 PD TDI engine (AWX).

On the Passat (2002) the intercooler hose connections were made via the spiggot and springclip arrangement. Not very air or oil tight! I assume the earlier A6's also had this arrangement.

On my current (2005) A6 which would have had one of the last 1.9 PD engines to be fitted, the intercooler hose connections are made via good old fashioned jubilee clips and as a result are both air and oil tight!

If your having problems with the connections, it might be worth investigating the possibility of fitting the later / or jubilee clip hoses.

I'm very pleased my car does not have those spiggot and spring clip connectors to the I/C. There are one or two on the upper hoses (I'll need to have a good look) that still use the springclips though.
Very interesting info you have there Col.

My 2003 AWX has the spring clip arrangement, just like my 2004 (54) AXC had in my van. My A6 isn't oil tight round that area either, it does drip oil out of there for sure. And the metal lugs wore out on the van. My AHF 2000 Skoda uses jubilee clips and so far hasn't leaked a drop from the intercooler area.

Why didn't VAG just stick to the jubilee clips?

Hmm...