EndlessCorners

Measured with VAG-COM.

Example

While cruising on the freeway after maintaining 75mph for the past 15 minutes.

Ambient External (dash reading) = 29C
IAT via VAG-COM = 50C
RPM = 2700ish

I noticed while the ambient temperature remained constant what I did with the throttle would change the IAT reading. Careful driving would get it as high as 56C while boosting would drop it to the low 40C range.

I ran the test in the FAQ, sensor came up nominal but I still suspect a possible failure which is why im asking.

Thanks for the knowledge!

ThetaTau87

Boosting lowered the IAT? That seems reversed. Is the sensor before or after the turbo?

SchwarzS6

the input air is warmed by the hot intake manifold. At moderate boost it does not have time to warm so the temp is a little lower. Then at high boost the heating from the compression of the air dominates.

What you are seeing is the same thing I see on my car with the TDS-1

UrS4boy

<center><img src="http://pictureposter.audiworld.com/15624/enginebaydevicelocations.jpg"></center><p><ul><li><a href="https://forums.audiworld.com/s4s6/msgs/150047.phtml">click for info on the IAT</a></li></ul>

EndlessCorners

excellent, Thank You! What intake temps are you seeing? Do you always have full boost?

SchwarzS6

When running on the highway I will see about 15C above ambient. If the car was run and allowed to sit for 15 minutes the heat will soak into everything and I might see a 40C above ambient temp until I am moving for 5-10 minutes. I do not remember the full boost temp rise at this time but if you need to know I do not trying a few times next time I am out

EndlessCorners

That would help. Im trying to determine if the ECU has a set intake temp where it defaults to base boost.

I keep on loosing full boost when my car warms up

-but-

If you always get full boost, even when hot, means I might be looking at the wrong thing.