S3 8l - turbo lost, trouble shooting steps

[Nick8l]

Hi all,

I was driving along the other day and heard a little zishhh and instantly lost turbo function completely.

Could someone point me in the direction of a troubleshooting guide? all the connections that I need to check etc. Haven't been able to spot any split/blown off pipework.

Also would like to confirm that it's okay to still drive if need be? trying to avoid it until I fix it of course.

While I was examining the engine bay I also noticed this (photos attached). Not actually sure what the connector is responsible for but appears to have coolant or some gunk on it.

Also, if there's a comprehensive guide to all the other things that a new S3 owner should do when buying one of these cars that would be ideal. I've got the tools and immense patience, and these forums appear to be a goldmine of knowledge which I'm slowly working through (just a bit hard to navigate).

Cheers,

Nick
Auckland, NZ

 

[hydro s3]

That is your parking heater or after run pump.
It should run for about 5 minutes after you turn the engine of. It pumps coolant round the turbo to keep help it cool down. I got one of auto doc about 5 months ago only £45.
Hey, check out BOSCH Water Pump, parking heater in the AUTODOC app https://m.autodoc.co.uk/bosch/663444
There is also links in the stickies you might want to read about buying these cars.

 

[Nick8l]

Cheers Hydro.

Still haven't figured out the boost issue but have some updates.

From cold, I'll usually have boost from anywhere between 5-30 minutes. Then all of a sudden it's gone, so it's either an all or nothing kind of deal.

Pipework has been checked, no leaks.

Originally thought it might be the blow off valve getting stuck open. Removed it and cleaned it, don't see how it could get stuck. When boost is gone I'm still getting the zish when foot is taken off the gas which makes me think that blow off valve and valve control solenoid is functioning as it should.

Now I'm thinking that it might be the wastegate actuator getting stuck open? I can't really think of any other components that could result in a sudden complete loss of boost. How would I go about examining this? and are there any other things that could be causing these symptoms?

 

[<tuffty/>]

Checked for fault codes?

<tuffty/>

 

[Nick8l]

Checked for fault codes?

<tuffty/>

No haven't done this. Is there a thread somewhere detailing how this is done? cheers

 

[<tuffty/>]

Info on reading faults can be found here dude

IMPORTANT! - When posting asking for help... - PLEASE READ BEFORE POSTING (UPDATED)

Hi all... As most of the posts people make are generally asking for help with issues with their cars can you at least make sure you specify the year and model of the car in question as (believe it or not) it can make a big difference in understanding where to start diagnosing your problems...

www.audi-sport.net

The fact you have boost for a while then it goes suggests soft limp mode... (is it cold where you are currently? relevant for one fault in particular...)

If the ECU is unhappy about something and decided to go into soft limp then it will have logged a fault code (or two) so reading those (preferably with a version of VCDS) will help with diagnosing whats going on

<tuffty/>

 

[Nick8l]

Info on reading faults can be found here dude

IMPORTANT! - When posting asking for help... - PLEASE READ BEFORE POSTING (UPDATED)

Hi all... As most of the posts people make are generally asking for help with issues with their cars can you at least make sure you specify the year and model of the car in question as (believe it or not) it can make a big difference in understanding where to start diagnosing your problems...

www.audi-sport.net

The fact you have boost for a while then it goes suggests soft limp mode... (is it cold where you are currently? relevant for one fault in particular...)

If the ECU is unhappy about something and decided to go into soft limp then it will have logged a fault code (or two) so reading those (preferably with a version of VCDS) will help with diagnosing whats going on

<tuffty/>

Thank you for that, I'll order one of those leads now.

In the meantime, is there much else that I can do?

Don't think it's been below 15°C at any time that I've been driving the car.

I've also noticed that the boost seems to disappear quicker if I drive quite hard, shifting at higher rpms. Whereas the other week I drove 200km+ on the motorway without really pushing it and still had boost, but then when I got up into the hills and started giving it a good bit of throttle, I quickly lost that boost. Not sure if that makes sense/helps to diagnose the problem, I can't make sense of it.

 

[hydro s3]

I'd get rid of the blow of valve and put on a standard Bosch recirc one.

 

[Nick8l]

I'd get rid of the blow of valve and put on a standard Bosch recirc one.

Yeah I've been thinking of getting rid of the blow-off valve from day 1, I'll order a recirc pump.

Still haven't got vagcom so sorta lost at the moment, if anyone has any other suggestions in the meantime, would be much appreciated.

 

[<tuffty/>]

Need the fault codes really dude... issue sounds like the ECU is unhappy about something and only way to find out what is to read the codes...

Do you have a boost gauge? or at least access to one you can fit to get some visibility of boost?

As standard the boost is around 12psi... under limp it will be on actuator pressure which is around 7psi

<tuffty/>

 

[Nick8l]

Don't have a boost gauge yet but it's on the list.

Car booked in for vag-com tomorrow so I'll get the fault codes.

Was doing an oil change today and noticed this broken off on the rear left. Some sort of tie arm sensor? could this be triggering the ECU in some way? looks like it's been broken off for a while..... will look into fixing it tomorrow but unsure of its function at this point

 

[<tuffty/>]

Thats for the Xenon lights leveling... there will be a similar sensor on the front left hand side.... fairly normal for these to break off if someone has been in there changing a spring or similar.... they need to be undone prior to that else this very thing happens

<tuffty/>

 

[danny_dj3]

i bought the obd11 reader and its been a godsend for me. pretty easy to use, easy to clear faults. might be helpful to find them fault codes.

 

[Nick8l]

I'd get rid of the blow of valve and put on a standard Bosch recirc one.

It's taken me more than half a year but did this today.... problem solved.

Thought I'd update the thread for anyone that comes across this with a similar issue.

These were the faults I had:
2 faults:
17608 turbocharger recirc valve mechanical malfunction
17705 connection charger - throttle valve pressure drop (not quite sure if this problem is also solved, haven't had a chance to properly look into it).

Was finally able to enjoy boost for as long as I please, a very enjoyable test drive indeed.
Also much prefer not having the loud "zishhhhh" between shifts.

 

[hydro s3]

That's good news mate happy for you.