1.9 AFN Cat broken

Hi, my grandfather told me last week that his A4 Avant 1.9 TDI has lost power 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 by me. So, I disconnected it and drove again. No difference. Therefore, it's not the MAF. The intake passages were also sealed. The variable turbine geometry (VTG) was working smoothly. The turbo 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 tapped on a defective catalytic converter, which explains the noise and also the loss of power, he explained to me. The detached monolith is partially "blocking" the exhaust, and the engine is running against a wall. Let's see if the suspicion is confirmed during the detailed check. It would be quite bad if the catalytic converter is already broken after 125,000 km. My grandfather always drives the car around 5.5 liters, I need 6.5 liters when I drive, and I sometimes borrow it to "burn off" deposits. Have you also had negative experiences with catalytic converters? Best regards, D.

Hello,

Have you ever hit the catalytic converter with a hammer or something similar?
When dealing with loose internal components, a clear and distinct sound should be audible.

[Translating...]

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

It seems like it might be an illness!

Hello,

You just need to sit on a dirt road somewhere and use a KAT (presumably a small vehicle) to pick up a rock.

Best regards, Rainer.

You're welcome, then it's probably like that. New part: €395, plus small parts and assembly...
Maybe I should look for a used one at RAR for around €230.

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

Best regards,


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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). That's why the 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, even a small amount of ruthenium in the oxikat will be "combusted" or "oxidized" further. This is more of a positive side effect, however.
By the way, the nitrogen oxides are completely untreated and are released into the atmosphere in their original form!

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 unburned HC is expressed 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.

Sure, here's the translation:

"Best regards."

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