hyperion

iTrader: (2)

I was all set to perform a relocation of the intake air sensor (which resides under the upper intake manifold) when I decided to do some testing. So I placed the sensor inside an aluminum tube and hit it with a hair dryer. Here's what I learned:

1) It takes about 3-5 seconds for the sensor to respond at all.

2) It took about one minute for the sensor to rise from ambient (about 15C) to the temperature of the air flow (about 60C).

3) Left to cool with no forced convection, the sensor took over ten minutes to cool to 37C.

4) With forced convection, this same cooling period took about one and a half minutes.

5) The IAT is very sensitive to the temperature of the brass base. Just by holding this with my hand, I could get the sensor to move several degrees.

All of this has me questioning the value of relocating the sensor. I guess that the relocated IAT will cool down faster than the stock location, which should provide better protection from lean conditions when the intercooler gets really cold. But what it won't do is allow the ECU compensation tables to be used in real-time.

On a related note, I plotted the temperature-resistance curve for the sensor. It looks a little like this:

30C: 1.6 kOhms
40C: 1.2 kOhms
50C: 0.9 KOhms
60C: 0.6 kOhms

This measurement was not super accurate, as I had to pull the sensor each time and measure resistance. But the curve looks pretty linear. Does anyone know if this is a standard sensor curve? If so, one option might be to purchase a K-type thermocouple and get an amplifier to convert the signal into something the factory system can use. I already have one of these for my SPA gauge, but I could get another one...

Any reactions? Anyone have a log of their relocated IAT from the dyno?

-ch

clayne

Thanks for this.

I'm going to be going with a different sensor manufacturer in the future, anyways. But the ohm readings are very valuable for calibration of a diff. manuf. sensor.

SomeGuy_sg

You can use back-pin probes to get the measurements from the sensor with out taking it out . For a more accurate reading

hyperion

iTrader: (2)

SomeGuy_sg: I had trouble getting probes in past the water grommets on the wires. I guess I could use a pin or needle--I'll try this tonight.

-ch

felix_is_alive

i used to run an additional injector setup where the injectors where on the inside part of the uim so i had to reposition my iat sensor ,...so i did ,it didnt seem to affect the quality or performance of my car one bit ,or at least i didnt feel anything.