Intake Air Temp

roachie

roachie

Taco Master
Joined
Nov 2, 2007
Messages
11,133
What is everyone seeing for the intake temps vs the ambient temps? Mine seems to be 50* warmer but it never changes. Hottest my temps get with twins is 121*. It just dont seem right.
 
That's about right. I logged a trip on my modis pulling enclosed trailer last summer with twins and my Intake air temp never got over 130 IIRC. I was very surprised how cool it stayed. The ambient temp was in the 90's
 
Hmm, I assumed it would be higher. After a hard run my hot side CAC pipe will burn your hand. Not sure how much I trust my sensor, it seems slow to respond.



CSnyder said:
Roachie, get on FB chat.
Click to expand...


I just now got back to a comp.
 
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The sensor reads air before its compressed....it goes up to 300 plus after its been squashed to 80mantain psi.
 
Depends on where your sensor is located...
Factory cummins sensor is near the back of the intake manifold, right by #6 cylinder so it reads the compressed air temp.
 
VP engines have an IAT and a MAP sensor in the rear of the head. They have nothing ahead of the turbo.
 
My 02 reads about the same, 50* over air temp. It is a thermistor, so the greatest resistance change is when it's cold. A few degrees change when it's hot doesn't matter much. The ECU seems to mainly use it for cold startup. A few years ago I played with changing the amount of resistance, to make it think that it was at a different air temp then it was. It did change the timing a few degrees (max of 7 if I remember correctly), but not enough to really care about. The biggest function it seems to serve is for the ECU to tell if the heater grid works. If it turns on the heater grid and doesn't see a rise in intake temps, it will set a code. On the 3rd gens, it uses the drop in battery voltage to see if the grid is working. It also uses it to tell how long a time to cycle the grid on. It uses coolant temp though to see if the grid should come on at all.

This is how it works on my 02 anyway. Different years maybe different.

Paul
 
Mine will read up to 40F difference while setting at idle. I noticed this in the hay field this year. It was 109F outside according to the overhead. The AIT was reading about 140-150 while idling in the field with minimual air through the CAC. Once on the road with 32K gross, even at 109F just having air moving across the CAC at 65 mph it would drop to about 130 on the AIT.
 
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