The IAT liesss

[Jake_rorx7]

So I've installed my own IAT sensor just before the throttle body. Its a common GM IAT sensor, calibrated by myself. The values correspond to another temperature sensor I have in the mouth of the vehicle for ambient.

The stock sensor lies - by a lot. At cruise, anywhere between 9-12c delta between my new sensor on the elbow, and the stock location, "fast reacting" iat sensor on the manifold underside. Just to be clear, the stock IAT reads well above my sensor.

Now there is a very slight difference in location, about 6 inches or so. But the different values are too high for the location to be the cause of this. I would personally put it down to the stock location being a heat soak prone material (metal), installed in a heat soak prone material (metal manifold), installed in a heat soak prone location (under the manifold). All sensors start out at ambient on engine start, but the stock IAT is diverging within 5 mins.

I see around 3-4c delta between my ambient temp sensor and my new IAT sensor. Until now, I was under the assumption that I have a 17c delta from ambient to intake. I've not done many harder pulls yet because I need to clear out the tank of meh fuel first, but still. Dont trust it! And if you have a custom ecu which uses that sensor data - maybe time to install a new sensor?

 

[RandomVillager]

Do you think the stock one has lost it's accuracy over the years?

I have heard the IAT on the RB series is basically a temp sensor for the cooling system so once that gets hot it takes ages to go down if at all till you let the thing fully cool off.

With a standalone you can put any IAT in the stock location I suppose and set calibrations to use that.

Could be worth maybe if possible using one pre turbo so see the delta better between the two locations. IC will show if it's getting heat soaked or not.

 

[Jake_rorx7]

Do you think the stock one has lost it's accuracy over the years?

I have heard the IAT on the RB series is basically a temp sensor for the cooling system so once that gets hot it takes ages to go down if at all till you let the thing fully cool off.

With a standalone you can put any IAT in the stock location I suppose and set calibrations to use that.

Could be worth maybe if possible using one pre turbo so see the delta better between the two locations. IC will show if it's getting heat soaked or not.

This particular sensor is only a few years old. I think it's just major heat soak.

If I can get my hands on one of those proper temp loggers with an array of tiny sensors I'll stick them all over the intake tract and get a better picture of what's happening and what's not. Pre turbo, post turbo, post IC, and around throttle body.

I think the key takeaway here is.. stock IAT sensor sucks.