kendalll

I was flipping through the measuring blocks on vag-com and saw that the intake temperature seemed kind of high. Outside air temp was about 55°F (57°F according to dash gauge) and the intake temperature was showing 99.5°F (37.5°C actual reading) while idling. Thinking that this seemed high I drove around the neighborhood a bit and it dropped down some 77°F (25°C). Got onto the freeway and it didn't get any lower than 67°F (19.5°C). Is this totally normal for a normally apsirated 2.8l?

It seems like the intake temp should be pretty close to ambient since the air is moving through the intake relatively quickly and there shouldn't be much pressure to increase the temp since there is no boost. (no vaccuum either since it's before the throttle)

I'm not really worried about it, just curious if there is some sort of correction factor to take into account or if I should expect this to be accurate and mine is off because it is old and dirty. (181k miles on the engine!)

Thanks for your time!

(1998 A4 Avant 2.8L Quattro Auto)
//idling good again thanks to vag-com helping diagnose a bad MAF!

S4_Cinci (I S'edTFA)

cleaner (Quick Drying) that says it is safe for plastics. Your IAT sensor is in the plastic intake pipe along the firewall (just before it connects to the intake mainfold). There is a wire connector on it. It is held in by an allen bolt, IIRC. Remove it, spray it with the cleaner and then replace it - it only fits in one way so you can't screw it up. If there is dirt on the sensor, and there will be after 50k miles let alone 181k, this could cause it to read too high as the sensor works by seeing how rapidly the sensor is cooled by incoming air as the sensor uses an electrically heated element for reference.

Intake air will be heated slight over ambient typically, but should read fairly close to the outside temp unless there is an error in one of these sensors - could be bad data from outside temp sensor as well.

kendalll

cool thanks I'll clean it and see, not that big of deal either way yet

S4_Cinci (I S'edTFA)

a Torx security bit (star shaped bit w/ hole in the center for the little nib that comes out of the bolt - can't recall which size, maybe T-20 +/- one size thus T-15 or T-25). Both of these sensors collect extremely fine black dust on the wires and this affects the rate of cooling which can give false data. The only danger is a bit of wasted time, as cleaning these should make the engine idle smoother for sure and might even increase your gas mileage as an added bonus! CRC makes a cleaner that I got at Advance Auto Parts for like $4. That can will last you a lifetime even if you have like 3 or 4 cars. Good luck!