High Fuel Consumption, No Soot?

Hello everyone,
Since I'm new here, I'd like to introduce myself.

'My problem with my Audi A6 2.5 TDi, manufactured in 09/96 with engine code AAT, is that it has lost some power and is consuming 1.5 liters more per 100km. This happened suddenly, not gradually. I've read a lot here and have already checked the AGR valve and cleaned the intake manifold. Regarding the behavior, the power boost that used to kick in around 2200 RPM is now gone. Also, there's no more black smoke coming out of the exhaust pipe when accelerating hard.'
Can you help me with a good tip?

greets inside

P.S. The friendly people we have here in the northernmost state aren't very knowledgeable.

HI!

*Is the motor dry on the outside?
Mileage?
*Oil consumption?
Is the air filter clean/new?

Since the mass airflow sensor is potentially an issue, but not likely the main problem, I'd suspect a mechanical issue. However, it's also possible you just got a bad batch of fuel, especially if the problem appeared suddenly.

Wheel bearing?
*Brake caliper stuck (is the brake disc excessively hot)?

Hi!

@ Julian

The AAT still uses the mass airflow sensor, which is known for its reliability and rarely fails.

To me, that sounds like a lack of boost pressure!

Unfortunately, I don't have time for any more guesses!
Hot tip: Have the error memory read out!

Best regards,
Andi.

To me, that sounds like a lack of boost pressure!


Or that, or a lack of compression in the individual cylinders...

Hello,

*The engine is generally dry, but there's a slight leak on the valve cover, which it's had before.
*Mileage is currently 230,000 km, and it still has a bit of life left in it.
Oil consumption is approaching zero, approximately 1 liter per 10,000 km.
*Air filter is clean, replaced annually. Diesel filter is new.
The wheel bearings are fine, and so are the brakes. It makes no noise and rolls very smoothly.

What makes me suspicious is that it's no longer producing any smoke; it always used to. The performance remains consistent across the entire RPM range, but previously, there used to be a slight increase in power around 2200 RPM.

Bad diesel is also a possibility, and this has been happening for the last four tankfuls.

Could it be that the injection timing was misadjusted during the emissions test? The technician had to repeat the test three times because the probe had fallen out of the exhaust pipe.

Can I measure the boost pressure myself? If so, where? And do you have a pressure gauge?

Thank you in advance for the suggestions.

Greets inside

Okay. Install a T-connector between the intake manifold and the pressure sensor. It should be an 8mm hose.

Hello everyone,
First of all, thank you for the help. I just picked up the car from Bosch, and they gave me the following information: They read the error memory, but no errors were stored.
Funding start date dynamically checked, 2 degrees too late.
AGR system not functioning. Exhaust gas recirculation pressure sensor checked, found to be mechanically defective.
I just bought it from Audi (for €85) and installed it.

Timing belt replacement overdue, therefore a boost pressure test is not possible.
The good one has 230,000 km on it and still has about 10,000 km left until the belt needs to be replaced, or is it too risky????

It would be great if someone could give me a tip.


Then, during the conversation, it was mentioned that the water pump should be replaced along with the belt, and that the total cost would be approximately 700 euros.
Should it be done by a specialized workshop due to special tools, etc., or can a small independent workshop handle it? How does the warranty on the work performed stand?


Thanks to you both, and I hope the little one gets back on his feet soon.

Greets Inside

hello boys,
Could someone please post a picture so I know where I need to go? I have absolutely no idea.

Thank you for your help.

greets inside

Hi,
I can create an image, but I don't have a website to upload it to.
"Using a pressure cooker doesn't make the dish unhealthy, but it's generally a time-consuming process."
I had problems with an independent repair shop: the rear belt was too tight, the injection timing was apparently adjusted with an Edding marker and by feel, which was far too early, resulting in a limp mode.
To measure the pressure, you don't need a fancy timing belt, or are they planning to do it while the engine is idling with free acceleration? For a normal test drive, significantly less than 3000 RPM is usually sufficient.
You should still consider changing it, though. In my case, the rear belt broke after 110,000 km. It's probably not just a matter of mileage, but also of age.

hello boys,
Thank you again for the tips; they really helped me.
I just measured the boost pressure using a pressure gauge.
Hopefully, the results will be good.
When accelerating fully, the turbocharger pressure reaches approximately 0.9 bar at around 3000 RPM.
is that enough or is something missing???

I was told by Bosch that the timing belt, or rather, the timing was 2 degrees late.
The start of the financing period might be the reason for the increased fuel consumption (1.5 liters).
Does that work? / Is that okay? / Is that what you meant?

Greets Insidedev

Hi,

0.9 bar is fine. 3000 RPM is not necessarily required: If you're accelerating slowly, for example, on a hill or on the highway with full throttle, the pressure should be reached more quickly. However, when revving up quickly in lower gears, the pressure may not quite keep up.