Engine Power Loss?

[boufant]

Hi All, this is post number 1 for me, so here goes...

My '03 Passat tdi sport lost power on my way to work the other evening, ie:- it would not really accelerate, as though turbo not kicking in. (this may well be because it hates going to work, just as I do..)
Anyway, enough of that...
However, after my shift ended this morning I got in my car and it ran as normal on way home??

I did have an instance of sudden lack of power while going through gears a couple weeks ago (esp 3rd) but it quickly went away, until last evening, when it lasted all of my 12 mile journey to work.

I decided to take it to a guy I have used for years, VW nerds apparently, and after explaining my symptoms he straight away said 'Turbo Knackered'. (I didn't want to hear that!)
I questioned it, asking about sensors etc, but he said I should take it for a test drive as follows:-

Get car up to about 60mph, then drop it a gear or two and floor the accelerator....and if the car did not accelerate (Turbo kick in I suppose) he said I should quickly turn ignition key off (not all the way of course) and back on (some sort of reset), and if the car then roared away and accelerated normally it would prove that turbo is on way out.
I did this down a nice piece of road at least 7/8 times (at different speeds, sometimes dropping to 5th, sometimes to 4th) and every single time the car performed and accelerated as it should. One time I sat at 40mph in 4th, floored accelerator and sat as it roared up to 90 mph as it just about reached redline before I upshifted....so to say the least I am puzzled, and not convinced that my turbo is shot...but I ain't no VW guru!!

All advice will be greatly appreciated, thanks in advance.

Cheers

Mark.

[quattrokid]

It sounds like your cars going into limp home mode. The ECU will have sensed a problem and it does this to protect the engine from further damage but letting you still get home. It is Not necessarily a Turbo issue but it may be, what you need as a proper diagnostic scan done on the car and it sounds like there should be logged fault codes which should then point you (or the mechanics) in the right direction. Switching on/off the ignition simply re-sets the ECU and so the car will run fine until the fault re-curs.
Can I suggest you consider another garage to the one you have been using, because they should have advised you all of the above and my worry would be that left to their own devices they would be currently unbolting your Turbo/charging you for the privilege, a Turbo which may well be fine and doing exactly what it was designed to.
This may come in useful; https://www.google.com/maps/d/viewer...8.kMTwqF0PoXwc It's the location map for Forum users who have Vag-com (diagnostic tool) and you may find someone in your area who will do the scan for you for less than a Garage, I have not been on here that long so just found it myself. It may be an idea to also do a search on here as you will find others who have similar problems, sure I have already seen a few, all the best with it

[Rob69]

Hi Mark, welcome to the forum. The car is going into limp mode, it will do this if the ECU detects one or more of several operating parameters are out of range or tolerance for the engine load, speed, throttle position etc at the particular time it kicks in, ( experts please correct me!). To confirm if it is the turbo you need to get the car scanned for fault codes and if possible collect some live data, this can usually help diagnose the fault better than just changing expensive components. what can happen with the turbo is the variable turbine nozzle guide vanes can get sticky, which is intermittent at first, that is probably what your vw guy was meaning, but it could be something more simple like the N75 valve that operates the guide vanes actuator and a cheaper, easier fix. Most folks here seem to use VCDS for fault finding and diagnosis, ask your vw guy to do some more diagnosis before commiting to a turbo change.
If you post the engine type, size and code ( 1.9 tdi AWX same as my passat maybe?).

[niall campbell]

Sounds like a Mass Air Flow meter is away

Usually after switching off , it resets itself, then just as turbo goes to kick in it cuts out.

However a scan with an autel vag505 ( £125 ) or an OBD2 reader will see Stored codes

[boufant]

Thanks for the reply Quattro, rob69, niall
The guy at the garage plugged his laptop in, and there were no fault codes to be found.
He quoted me about £600 to short out turbo, just for information.....

[Rob69]

Reading your OP, you've booted it through the gears several times which can clear the VNT mechanism for the time being. Not sure why it hasn't logged a fault code, driving the car with the laptop hooked up and taking live data would allow turbo boost, MAF readings, N75, etc to be checked. Have you checked the basics such as split or perished vacuum hoses to the turbo vnt actuator, clean air filter?

[Crasher]

I find it hard to believe that either code 17964 or 17965 were not stored in the ECU so I suggest firstly you get a proper code read done BUT it is likely that the turbo needs rebuilding and this would show code 17965.

[boufant]

I haven't checked anything myself Rob.....a bit unsure as to what/where to look to be honest..

[boufant]

hi Crasher,
yes, no codes found when he plugged his laptop in, and since Wednesday evening she's ran fine.....
when I get time i'll seek out somebody to do another code read...will she be ok for a couple of weeks, I got some days off then?
Iv'e seen you mention the AMM before, is this a possibility?, but, if a rebuild is needed, what am I looking at as regards $$$$$$
Cheers Mate.

[Crasher]

It is a vague possibility it is the AMM but I have only seen it once and it was causing over-fuelling as well with accompanying black smoke but no boost leaks so it was easy to find, it left no AMM fault code, just an over-boost 17965. The turbo is a little easier to do on a 3B than a Golf and I would say you are typically looking at £850>£900 for a reconditioning of your unit including an oil change but not the oil supply pipe if it twists.