Page 1 of 1

Ambient air temp. reading

Posted: July 14th, 2012, 11:52 am
by bjf
Hi.
Did some logging today, following my fmic install.
Since i was on a holiday trip i didn't go in to much detail, but i watched the ambient air temp and boost air temp.

Anyways, noticed something strange about the ambient air temp. reading:
The outside temp. was suppose to be around 20C according to wheater services, the cars info display also read 20C.
However, VT read a value of 31C as ambient air temperature.
How is this possible, where does VT pull the ambient temp from?
IAT was NOT logged at the time.

/Bjorn

Re: Ambient air temp. reading

Posted: July 14th, 2012, 4:34 pm
by mituc
Only Gen2 reports the AAT (Ambient Air Temperature) through OBD2. Most probably what you were looking at was the Intake Air Temperature which is close to the ambient only during high speed cruising (around or above 50mph/80Kmph).

However, if you own a Gen2 then it's possible that the ambient air temperature sensor to have been heat soaked previously and not ventilated enough to read the AAT correctly.

P.S. wherever you are, I think I'd like to live there. I'm getting tired of tuning my car in +40C weather during summer or -30C during winter. :)

Re: Ambient air temp. reading

Posted: July 15th, 2012, 8:39 am
by bjf
I'm in Finland, 20C is pretty normal in the summer.

I got an 06 MPS 6.

Did some further logging today and logged both ambient air temp. and intake air temp and sadly they DO NOT correlate.

Actual air temp today was 20C, VT read ambient 34C, intake temp. 49C :(
What might be going on here?

Re: Ambient air temp. reading

Posted: July 15th, 2012, 10:38 am
by Steve @ VersaTune
Gen1 3 MPS does not support ambient air temp via OBD. I'm not sure where that sensor is located. The ambient baro sensor is on the ECU PCB.

Try logging all of these temps after the car has been off for a long time (overnight) and all sensors should be reporting the same temp. They should read very close then.