Charging Air Temp/Pressure Sensor: Do You Have It?

Hello,

I'm curious whether the AXR has a sensor for charge air temperature and pressure. I couldn't find anything related to that in a wiring diagram I have. Unfortunately, there's no information about it on the CAN bus, or I might have missed it. And any measurement values wouldn't be helpful because I need the values either on the CAN bus or as an analog signal.

If it has sensors for that, where can I find information about them?

Sure, I'd be happy to help you.

I've done a little searching, but I can't completely rule out the possibility that I've missed something. So, please don't jump on me right away for my first post .

Thank you and best regards,
Christian.

Sure, he has sponsors for it, and they are also included in the circuit diagram.

You have mail.

-piit- wrote:

I'm curious whether the AXR has a sensor for charge air temperature and pressure!? In a schematic diagram I have, I couldn't find anything in that direction. Unfortunately, nothing comes through on the CAN bus in that regard - or I might have missed it. And any measurement values wouldn't help me, as I need the values on the CAN bus or analog. If he has sensors for that - where can I find information about it?

Hi,

"The sensors" are typically combined into a single multi-sensor unit in the AXR, which is located in the engine control unit (at least in the G4 and Polo 9N models).
In the CAN bus, the values are not typically transmitted because they are only evaluated by the MSG (Message Generator).
You can, of course, directly measure the analog voltages (the two wires that do not carry ground or 5 volts) at the sensor: the LD signal increases with pressure, and the LLT signal decreases as the LLT increases.

Thank you for your answers .

I just did another short test run. It seems the charge air temperature is actually being read on the CAN bus. With an outside temperature of 20°C and a short burst on the highway, I was able to measure temperatures of around 60°C. That should be the charge air temperature. However, for some reason, it's labeled as "outside temperature."

The boost pressure, however, cannot actually be found on the CAN bus. That's a shame :/ I guess I'll have to deal with the analog signal sometime .

-piit- wrote:

The charge air temperature apparently is being read from the CAN bus. With an outside temperature of 20°C and a short drive on the highway, temperatures of approximately 60°C were measured. This should then be the charge air temperature. However, for some reason, it is displaying "outside temperature".

If this value quickly drops within the Pmax range and the gas is cut off (transitioning to thrust mode) after approximately 30 seconds, and remains about 5 Kelvin above ambient temperature about 1 minute later (at the lowest possible load), you have most likely found the LLT (Laminar Flow Transition).

Then I would be interested to know which other components, besides the engine, actually require this size.

Then, I would be (on the side) interested to know which other components, besides the engine, actually utilize this size.

Hello Ulf,

Neither of the two, except perhaps a visual display as a gimmick for the driver.

In the DBC file, you can find information such as boost pressure and intake air temperature.
However, except for developers, no other STG (Standard Transfer Gateway) besides the MSG uses these parameters, so you won't find the corresponding IDs in the production environment.

(at least, that's what I've observed in all my measurements).

Sure, here's the translation:

'@-piit-'

If the DBC file says 'Aussentemperatur' (outside temperature), it should actually represent that, or the DBC file is garbage. Feel free to send me a private message with the ID where you found it.

But I suspect there's a sensor that's not detecting what it should be.

Best regards, Jochen.

The signal is named MO3_OutsideTemperature... The DBC file is ANT_412_DQ.dbc.

As a comment, it states: "In the SDI system, the intake air temperature is displayed here."
FFh = Error.

Given that the values were very suitable, I am very confident that this is indeed the LLT.

Regarding boost pressure, it currently states "only available for Porsche" ... You would need to own a Porsche .

Hello.

This signal actually represents the charge air temperature from sensor G72.

However, this value is referred to as the outside temperature because, in vehicles without turbocharging (SDI), it can be used with a certain degree of accuracy as an outside temperature sensor. The measured value is then used in the instrument cluster if it does not have its own sensor.

HI.

In which measurement block is the charge air temperature displayed in VAG-COM?

Sure, here is the translation of the text from German to English:

"MFG" is an abbreviation for "Mit freundlichen Grüßen," which means "Sincerely" or "Best regards" in English.

pa-mm6 wrote:

In which measurement block is the charge air temperature displayed in VAG Com

Are you looking at VAGCOM log files (download) on the FA (Forum Auto) website?