Audi A4 B7 TDI Intercooler Frozen - BRD 170PS

Hello everyone,

"Over the weekend, my intercooler froze on the left side (-12°C)! I was able to start the engine, but it ran roughly at idle and I couldn't get the RPMs above 1500."
Upon opening the hood, I observed that the hose connecting the left intercooler to the engine had almost completely collapsed due to the prevailing vacuum. Lacking any other options, I thawed the intercooler (or the connecting pipe to the right intercooler) using a pressure washer at a nearby self-service car wash. This took less than 2 minutes, and there were no further issues after that. Since then, there have been no problems, as the temperature has been a maximum of -5°C. Today, I removed the hose to the left intercooler, and I can see condensation with a slight oil emulsion. What can I do? Is this a known problem? Is there a leak somewhere?
On the right side, I haven't been able to check the hoses yet, as the air filter and other components need to be removed. Or, a lift would be necessary...
It should be noted that I purchased the vehicle with an AT (automatic transmission) engine. It's possible that something was tampered with.
How can I use VCDS to check the boost pressure (target values?) in order to rule out leaks without having to do a lot of disassembly?

Thank you very much for your help!

Hello,

Quote:

How can I use VCDS to check the boost pressure (target values?) in order to rule out leaks without having to do a lot of disassembly?

Measurement block 11.
However, the target pressure is easily achieved even with small leaks, which is why the air mass should also be checked under full load.

"This type of problem is new to me, but it could be conceivable with a lot of short-distance driving under light load. After all, the crankcase ventilation system feeds into the intake manifold before the intercooler (specifically, directly behind the mass airflow sensor and before the turbocharger), which ensures an adequate supply of moisture."

Does the engine oil look okay?

Best regards, Rainer.

Hello Rainer,

Thank you very much for the quick assistance!
The Audi drives 40 km to work and 40 km back each day, so it's not really short trips, although the maximum speed is 140 km/h with not much load. The problem occurred on Saturday. On Friday, it returned from work and then drove about 5 km in city traffic.
I will take a look at the oil tomorrow.

What I had assumed was that the loader could "compensate" for minor leaks.
Therefore, the idea of measuring the air mass is a good one! Which measurement block should I measure, and what value should I achieve under full load?
"Something I've noticed for a while is that the engine has a "turbo lag"; however, it's a delayed response of about 1 second at engine speeds of 1800-2200 RPM."
That should be normal for that engine, as far as I understand.

VG
Björn.

@Rainer: Frozen water in the cooling system is not a new issue; there was information about it in the "1A-Werkstätten" publication!

Hello,

@T3Surfer: Thanks for the information!

"@B.C.: In measurement block 3 (actual air mass), the significantly high air mass values at full throttle indicate a leak. It should be noted that air mass values tend to increase at lower ambient temperatures."
You can reliably detect a leak with this method if you have comparison values for your car, for example, from the previous winter.
Without reference values, the measured values are of limited significance because, for larger changes, the leak would have to be so large that it would be noticeable as a hissing or whistling sound when accelerating.

Best regards, Rainer.