Touran 2.0 TDI: "Lean Misfire" Troubleshooting

Hello,

Today, we're not talking about my car, but about my dad's Touran (manufactured in 2007).
As far as I've researched, it's the 8V 2.0 TDI with 140 horsepower and approximately 180,000 km, and the 16V model came later, as I understand it.

The car is experiencing a "jerky" or "stuttering" problem (I'm not sure how else to describe it), and no one wants to believe my father, or rather me (because I always try to explain it). VW keeps sending us away with the phrase "state of the art."

The car drives normally, but as you approach a red traffic light, you start braking gently. From approximately 15 km/h, the car starts to vibrate slightly. It's most similar to someone briefly tapping the brakes at very short intervals and then releasing them. You can clearly feel this inside the car; for example, your trouser legs might "flutter," and the steering wheel picks up these vibrations. A passenger will notice it very clearly, especially if they have their feet flat on the floor.
We installed new drive shafts (they were due for replacement anyway), completely new brake discs and pads, and also added brand new alloy wheels with brand new Hankook Evo 12 tires (17"). The shaking/vibration is still present.
Okay, so I had an idea to test some things in a parking lot. I started by doing a few full stops from low speed, then gradually slowing down to see if it might be temperature-dependent. Then, my father drove with the hood open, and I ran alongside the car, observing the engine as he slowly braked. I suspected a loose engine mount. Finally, I drove again and, while braking, I slightly increased the throttle, just enough to have a slightly higher idle speed. The jerking was completely gone! This can be reproduced 100% of the time, and it wasn't a coincidence. When the air conditioning is on, the jerking is also gone, which means it must have something to do with the amount of diesel being injected. So, either there's something wrong with the engine software (no chip tuning!), or, and this is my suspicion, the common rail injectors are starting to get clogged. The car drives well, the performance is good, and I can comfortably reach a speed of just over 200 km/h on the speedometer.

I've read online that VW has issues with this engine and the PD injectors, and that they sometimes offer cleaning using an ultrasonic bath. However, the dealers always send us home without providing further information, so I'm not sure what's going on. Does anyone know anything about this?

What do you think of my "diagnosis"? Could there be other causes, or did I more or less hit the bullseye by chance?
Is it possible to easily increase the idle speed using a diagnostic tool?

Thank you very much.

Best regards, Christian.

Hi,

If it's a 2.0 TDI 16V engine without a DPF (engine code: ACV), with control unit number 03G906016EH and software version 375893, then the problem is likely due to a software bug.

Please check if it's really an 8V! Engine identification code .

I'll do that as soon as I have the car in front of the door. It has a DPF, which I forgot to mention.

PS: I also have an old VAG-COM lying around that used to come with a cable from eBay (why can't I write that here?), and I'm not sure if I can still use it to read the exact software version.

Quote:

He has a DPF, I forgot to mention that.

Then it's probably an 8V model.

Quote:

VAG-COM flying around, what it used to be with an e B a y (why can't I write that here?)

Because it doesn't include a support key, and also no VCDS software from the Dieselschrauber Shop.

But that's why you should be able to write the word, right? Never mind, I seem to remember that it was only a demo version anyway. A few things could be selected, but many others weren't even included. I was able to query a few errors from the car with it, that's why I got it back then. I should probably look around to see where I have it, but I'd rather go to VW for that kind of thing; they have Bluetooth adapters now .

Quote:

Then it's probably an 8V.

In the evening, the car will be back, and then I can take a look .