AFN Cat Adapter Broken: Troubleshooting & Repair

Hi, my grandfather told me last week that his A4 Avant 1.9 TDI doesn't have any power anymore and that it's making clunking and rattling noises. It's probably something with the exhaust...
I was test driving it, and he was struggling to reach 80 km/h. The mass airflow sensor (MAF) was replaced three months ago with a Pierburg unit. So, I disconnected it and drove again. No difference. So, it's not the MAF. The intake passages were also sealed. The variable turbine geometry (VTG) was working smoothly. The turbocharger had a consistent operation. Is the pressure sensor broken? Is the wastegate valve sticking intermittently? Because suddenly, it had full power again. Today, the mechanic at the dealership suggested a faulty catalytic converter, which explains the noise and the loss of power. He explained that the detached monolith partially blocks the exhaust, and the engine is working against a wall. Let's see if this suspicion is confirmed during the detailed check. It would be quite a problem if the catalytic converter is already failing after 125,000 km. My grandfather usually drives it around 5.5 liters per 100 km, I need 6.5 when I drive it, and I sometimes borrow it to "burn off" deposits. Have you also had negative experiences with catalytic converters? Regards, D.

Hello,

Have you ever hit the catalytic converter with a hammer or something similar?
When dealing with loose bowels, it should be quite noticeable.

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Hello, on my Passat, the catalytic converter came loose at 93,000 km.
It was awful, like a plague!

It seems like it might be an illness!

Hello,

You just need to sit on a dirt road and use a KAT (presumably a type of vehicle) to pick up a stone.

Best regards, Rainer.

You're welcome, it seems that's the case. New part: €395 plus small parts and assembly...
Maybe I should look for a used one on RAR for around €230.

To the best of my knowledge, the KAT (presumably an acronym) is not relevant for the AU (also presumably an acronym).
And besides converting Russian particles into smaller Russian particles, the Oxikat doesn't really do anything else.
(please correct, wrong).
Okay, so I recommend using a hammer and chisel to separate yourself from that broken cat.

Best regards,

Sorry, Tagessuppe, but I have to disagree with you from this point on!

The catalytic converter's primary function is to oxidize unburned hydrocarbons (HC) and carbon monoxide (CO) into carbon dioxide (CO2) and water (H2O). This is also the reason for its name.
The fact that HC tends to adhere to the Russian particles, thereby freeing the Russian material from its load, does not diminish the significance of soot, a component of the exhaust, in relation to the oxicat.
Certainly, a small amount of ruthenium will also be "combusted" within the oxicat. However, this is more of a positive side effect.
By the way, the nitrogen oxides are completely untreated and are released into the atmosphere in the form they are produced.

Regards,
Alex.

From what I've heard about TDI engines, their CO and HC emissions are supposedly zero.
Due to the high combustion temperatures, very little CO is produced. Furthermore, the excess of oxygen (in gasoline engines, a Lambda value less than 1 indicates an oxygen deficiency) results in almost no...
unburned hydrocarbons. And the presence of unburned hydrocarbons is indicated in Russian.
The real "problems" with direct injection engines lie in their NOx emissions.

Unfortunately, I don't know the exact emission data for a TDI engine, but to the best of my knowledge...
They are in the per mille range.

Best regards.

Regarding the issue of exhaust emissions, the following information is publicly available: