[Seat7A]

My 2016 TDI V6 with 91,000 miles recently developed intermittent power delivery causing hesitation and stumbling during light throttle application and light throttle lift. The issue is most pronounced when the engine is between cold and full operating temperature. There are no issues with cold or hot starts or idle. Full acceleration feels normal. The engine is throwing no codes.

Thankfully, my dealer was able to reproduce the issue multiple times and consulted with VW of America. VW decided, as a start, to replace all six injectors at their expense.

I'm putting this out on the forum in case anyone else encounters the same issue and will report back once the issue is fully diagnosed and fixed.

 

[volkswagens-for-life]

Let us know how it goes. My first guess would have been the injection pump letting go lol

 

[RocketTech]

At least then he'll have new injectors AND a new HPFP

Let us know how it goes. My first guess would have been the injection pump letting go lol

 

[volkswagens-for-life]

At least then he'll have new injectors AND a new HPFP

LOL

 

[Matthew Nelson]

One would hope that they have some sort of diagnostic data pointing towards faulty injectors. Throwing parts at the problem sounds more like incompetent technicians but hey who cares its their dime?

 

[Seat7A]

Update -- After three weeks my VW dealer still has the Touareg and is working diligently with VW of America engineers to solve the problem. Right now they're still unable to determine the cause of the power delivery problems. First, they replaced all fuel injectors. That didn't work. Fuel delivery pressure at the injector rail is normal, as is performance of the high pressure fuel pump. They drained and replaced the fuel. Just today they identified lower-than-normal pressure in the fuel return line, but so far they're unable to determine why that's happening.

They've given me a Tiguan loaner and are picking up all costs, so they deserve full credit for making a best effort. When the mystery is finally solved I'll report back again.

 

[Seat7A]

Finally, after more than one month, I have my Touareg back and it's running normally. The dealership, working with VWofA technical support, went through a series of tests and actions before arriving at a solution. The fix was, according to my service rep, reinstalling the vehicle software. Given the dependence of today's vehicles on computer software and hardware, one would think a software reboot would be one of the first things they tried, but it wasn't. They replaced all six injectors, removed and drained the fuel tank (which was pristine inside) and tested all electronic connections to all fuel and emissions systems components. Only then did they perform the software reload. Thank goodness this cost me $0. The extended diesel emissions warranty covered everything. The dealership gave me a 2021 Tiguan for the duration of the repair. Nice vehicle with updated electronics (e.g. Apple Car Play), but compared to driving the Touareg it was light, buzzy and felt like a bit of a toy.

My HPFP was fine. I credit its condition and the condition of the fuel tank interior, in part, to the Stanadyne fuel additive I've used with every tankful for 5 1/2 years.

I hope we can say the book is closed on this case, but if not I'll be back with another update. In the meantime, I hope this may have helped any other V6 TDI owners with similar issues.

 

[volkswagens-for-life]

Great follow-up, glad it's been rectified too!

 

[TommiT]

Yes, it does seem daft that you wouldn't attempt the easiest and cleanest fix before ripping a car apart at random.