Intake Air Temperature Sensor for Audi ARL Engine

I can't find that part either in the engine compartment or in the documentation.
When using VAG-com for diagnostics, the intake air temperature sensor reacts very slowly to changes in load. Therefore, I wanted to check it.
The only relevant sensor is located in the pressure pipe between the coolant pump and the intake manifold. It has the part number 038 906 051A and four connectors.
According to the documentation, it should only be a pressure sensor.
Does anyone know more details?

Hello Felix!

As far as I know, the sensors installed in the pressure pipe (after the low-loss fitting) are combined temperature and pressure sensors.
On my AGR engine, this combination sensor is located on the front left side of the engine compartment, precisely at the 90-degree bend in the pressure pipe that runs from the intercooler (IC) downwards and towards the rear to the intake manifold.

Regards,
Alex.

Hi Alex,

Thank you for the quick response.
I'm going to try swapping it out temporarily (borrowing it, not buying it, as it's too expensive).

Deleted upon request.

Hello Gustav,

My problem is that my car no longer reaches the same top speed as it did before winter.
It's about 10 km/h slower now. I unfortunately haven't performed a pull test according to Ulf's table, so any statements about acceleration are rather subjective.
I've been trying to find the cause since I put my summer tires back on.
There were no modifications to the vehicle during the winter months.
Only at the Volkswagen service center was the 90,000 km inspection performed, including a timing belt replacement.
According to their statement, both the clockwise and counter-clockwise positions are locked. Therefore, I can rule this out as a source of error.
Various diagnostic tests performed with VAG-COM did not yield any results.
The only thing I noticed was a slightly decreasing air mass curve in the higher RPM range. After that, I replaced the Mass Air Flow sensor (MAF) – completely free of charge after I showed them my measurements.
No change.
As the next step, I had a performance test done by my chip tuner specialist.
175 horsepower according to its dynamometer reading?
Then I measured the exhaust pressure before and after the catalytic converter.
0,29 bar vor und 0,25 bar hinter dem Kat. Sure, here's the translation:

"So, even I.O."
Currently, my only thought is that the PD elements might not be injecting as much as they should.
One indication of this is that I've been seeing slightly less smoke lately when accelerating in second gear.
The issue with the temperature sensor was just a red herring; it's illogical because if that were the problem, VAG-com would have to show a low amount of electricity being used.
I was just driving on the highway at full speed for a while.
The intake air temperature was approximately 40 degrees Celsius when the outside temperature was 19 degrees Celsius. I think that's a realistic reading.
Currently, I'm running with half a tank of diesel fuel mixed with a cleaning additive. Just now, the maximum speed according to the speedometer was around 220 km/h in both directions. That's slightly better than it was before I tried the cleaning process.
Before winter arrived, the car was showing a speed of approximately 230 km/h on the speedometer.

felix wrote:

The maximum speed, according to the speedometer, was about 220 km/h in both directions a little while ago. That's slightly better than it was before the cleaning attempt. Before winter, the car was showing a speed of approximately 230 on the speedometer.

Hi.

I don't put much stock in these "Vmax" measurements.

Once you have a tailwind of 5 km/h, and another time a headwind of 5 km/h, and that's enough to measure your "loss" at 10 km/h (under otherwise completely identical conditions!) .

With a wind speed of 5 km/h, you practically won't see any movement in the trees or blades of grass when viewed from below.
Even the smoke from chimneys still rises almost vertically...

Um... Ulf,

I entered "220" in both directions. That's when I didn't measure any loss at all.
I haven't exceeded this limit of 220 for months, and that's under specific conditions.

Deleted upon request.

Hello Gustav,

First of all, thank you for the tip about the tandem pump.
I'm going to make a fitting for my pressure gauge.
Regarding the speed at 220: It is approximately 4200 RPM.
I'm already driving with the increased tire pressure.
Regarding the accuracy of the speedometer reading: It's true that there can be a discrepancy, but the fact is that it has decreased by 10 km/h.
You're probably right that it won't kill you.
I'm going to increase the dosage of the cleaner now.

Thank you again for the tips.
I will report when there are any new findings.

felix wrote:

I wrote 220 in both directions.

I didn't measure any loss at all.
I have not exceeded this value of 220 for months under condition x.

Hi.

Okay, I missed that.

Have you had different tires since then?
Even the permissible tolerance in the rolling circumference for the same tire size , which is 0.5 / -2.5% compared to the standard value, can shift the speedometer reading by up to approximately 9 km/h at a speed of 220 km/h.

If you change the tire size, you might experience apparent changes in top speed of over 10 km/h }, even though the engine doesn't produce a single horsepower more or less.

Hi Ulf,

Unfortunately, it's not any of the other tires either.
Just the summer tire set from last year.

Gustav had already mentioned the issue of coking.
A friend also gave me this tip, mentioning that it is not uncommon for combustion gases to enter the injector nozzles and cause carbon buildup, especially in diesel engines with high power output and therefore high peak pressures.
Maybe the cleaner will help. By the way, it's called Pro-Tec and is available from Bosch service centers.
Are there any better products available?

Have you ever measured the turbocharger's boost pressure?

Have you cleaned the intake passages and intercooler (IC) etc.?

Hi Julian,
All target values, including air mass and boost pressure, are within the normal range.
It looks like we'll probably end up using Gustav's suggestion about the coking process.
I'm going to keep using this cleaner for a while longer.

Just changed the air filter?