Differential Pressure Particle Filter: Causes & Solutions

Hello everyone,

I recently bought an Audi A3 8P with a 2.0 TDI engine, specifically the BMM variant with 140 horsepower.

It feels like it has a maximum of around 120 horsepower, in my opinion. It's lacking a bit of power.

'The boost pressure readings, smoke levels, and air mass values all look good. The engine has 100,000 km on it.'
Oil consumption could not be determined.

I only have a pressure difference at the particulate filter:

Motor standstill: 0 mbar.
Partial load: between 20 - 70 mbar.
Full load: approximately 300-370 mbar (this seems a bit too high to me; it should be no more than 300 mbar).

Offset printing at 10.5 mbar.

Ash content: 28 grams.

The car runs perfectly fine, but it feels a bit too tame; it reaches its top speed.
No error codes.

What could that be? I was planning to remove the intake manifold in the spring and verschandeln out any carbon deposits, but is it possible that the particulate filter is somehow restricting performance more than usual?

BMM is the 2.0 8V DPF engine.

Does it also have camshaft problems, like I read about recently from other people (I think it was on a BLS 1.9 8V DPF forum)?

That would certainly fit perfectly with your description.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Yes, that's the 8V one.

I have no idea if he's having problems with it. Unfortunately, I have to take the cover off to check, but I was planning to do that in the spring when it gets warmer. That way, I can see what's going on.

There are no clicks or other noises present.

The top speed is fine, but it feels sluggish.

My old A3 ALH with only 90 horsepower, manufactured in 1998, makes his life difficult up to a speed of about 150 km/h.

'Yes, in my opinion, the fuel consumption is a bit too high (0.5 to 1 liter) too much, no matter how I drive.'

Hello Darkcali!


If the box easily reaches its maximum speed and doesn't display any errors, what does the airflow look like?
Have you driven any other BMM vehicles for comparison?
Don't rely too much on your gut feeling.

The older A3 with 90 horsepower has a relatively short gear ratio compared to the BMM transmission.

DPF boxes usually need a little more diesel.


Greetings from FFM .

Hey T3 surfer, how are you doing?

So:

The air mass readings are good, there's no drop-off, and it's reaching the target value at every RPM.
Similarly, the boost pressure follows a textbook-like pattern.

What bothers me more than the somewhat weak performance is the fuel consumption, which I find too high.

The ALH engine typically consumed between 5.5 and 8 liters of fuel per 100 kilometers (full throttle), but on average, it used around 6 to 6.5 liters.

The BMW typically consumes between 7 and 9 liters of fuel per 100 kilometers, with an average consumption of 7.5 to 8 liters.

I find that a bit excessive. Different things like weight, translation, DPF, etc...

However, if anything is clogged or carbonized, I would like to locate and resolve the problem.

What do you say about the differential value? According to VCDS, it should be a maximum of 300, but I'm getting up to 370 .

Wie hoch geht der Diffwert bei frisch reg. DPF?

During a "filling phase," it's difficult to assess the value because no one really knows how much Russian vodka is actually in it.

Shortly after a registration, one should be able to assume that the system is "empty."

I also get a reading of 339.7 mbar difference when the DPF is empty (I've only logged this once while paying attention to it).

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hello Darkcali,

Okay, as always .

The old ALH is a VP engine, which was very fuel-efficient to operate. The BMM, on the other hand, is a PD engine that was adapted to meet emissions standards. These engines tend to consume more fuel, especially if they have the silly "green" cork installed from the factory, which likes to use an extra portion of diesel for cleaning.

If the DPF is almost clogged, then the load and air mass would also cause the fuel injection amount to decrease! Do you know anyone else who drives a BMM engine?

Unfortunately, I don't know anyone who would let me log data or do a comparison test.
Furthermore, it must also be a BMM (Best Matching Machine), otherwise it doesn't make sense.

I didn't pay attention to the filter regeneration status and took a trip 'in the middle' of it. I'll try using a freshly regenerated filter next time and see what value it reaches. I always thought that this maximum value shouldn't be exceeded, regardless of when it occurs.


The exhaust gas temperatures look good so far; I'm not exceeding 800 degrees Celsius before the turbocharger, according to the measurement block.

So, can I rule out a partially melted or clogged particulate filter?

Because the differential pressure is the only value that deviates from the expected range, while all other values appear to be within normal limits.

So, I went on another logging trip again:

Abnormalities:

Rotation angle at -2.0 to -2.5° KW (should a fine adjustment be made?).
How reliable is this value?

Exhaust gas temperature must never exceed 820 degrees Celsius.
BUT: Under full load, it naturally decreases because more fuel is injected. At partial load, after a quick drive, it remains at 800 degrees Celsius regardless of whether I'm driving at 2200 RPM and 130 km/h or faster. As soon as I give it full throttle, it immediately drops below 800 degrees.

Is it normal for the exhaust gas temperature (EGT) to remain at 800 degrees Celsius even when driving at a leisurely pace?

Injection volume: maximum 55 mg per dose.

Quote:

BUT: Under full load, it naturally goes down because more fuel is injected. At partial load, after a quick drive, it stays at 800 degrees regardless of whether I'm driving at 2200 RPM and 130 mph or faster. As soon as I give it full throttle, it immediately drops to below 800 degrees. Is it normal for the exhaust gas temperature (AGA) to remain at 800 even during relaxed driving?

Your particulate filter has been regenerated, and your assumption about full load is incorrect.

Do you mean active regeneration by that?

It should be visible on the display, shouldn't it?

I've experienced this observation multiple times, even on the same day. I haven't driven more than 200 km.

That would mean he regenerates very often.

Why is the exhaust gas temperature (EGT) decreasing at full load according to the sensor? I thought the fuel injection amount increases to a maximum to avoid critical temperatures, or am I mistaken?

Quote:

Do you mean active regeneration by that?

Yes.

Quote:

It should be visible on the display, shouldn't it?

No.

Quote:

I have observed this phenomenon multiple times, even on the same day. I haven't driven more than 200 km. That would mean that he regenerates very often.

Yes, or he won't finish it.

Quote:

Why is the AGA temperature decreasing at full load according to the sensor? I thought the injection量 increased to a maximum to avoid critical temperatures, or am I mistaken?

Cognitive biases.

Just take it for a test drive in an identical vehicle or have a performance test done.
Anything else, especially speculation, ultimately leads to nothing.