I tested my Intake Air Temperature sensor going by this chart previously posted...



... and it read 3.4 at 70 degrees which is pretty much right on the money.

So I put a hair dryer on it for a few seconds, and it went down to 1.0 fairly rapidly (within 5 seconds) which also seems normal going by the chart. But when I took hair dryer off the sensor and allowed it to come back to room temperature, it didn't happen in 5 seconds, it was a VERY slow climb back to 3.4 (took 90 sec to 2 min).

Is it normal for the IAT sensor to have rapid response readings in one direction, but slow response readings the other direction?

[This message has been edited by Skybax (edited 05-17-2021).]

Might be more of an accurate "speed" test, if during the cool-down portion, you keep the blower aimed at the sensor with the heat turned off.

Good suggestion, I will try that tomorrow afternoon when I get home...

quote Originally posted by Patrick: Might be more of an accurate "speed" test, if during the cool-down portion, you keep the blower aimed at the sensor with the heat turned off.

Yes, w/o air moving the sensor have enough mass that cooling down just w/ convection can be slower.
air moving the NTC element should follow air temp.
air not moving NTC element is slower and the likely see temp and/or even lower air flow from sensor case too.

Note: When you drive then shut down, then sensor and air can get heat soaked for awhile and actually reads higher before whole engine bay cools. V6 w/ sensor in air cleaner doesn't get really hot. 87-88 w/ sensor In the Intake Manifold sees hot temps even at idle.

NTC element that reads air temp is inside and can be hard to see depending on "screen" design protecting the element.
Plus If has metal screen then the element is electrically insulated adding mass to cool/heat the part to read. Plastic screens then element maybe insulated or not.
In ECT and others you never see the element, only tip of case to seal as one piece.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Ok, I did the test again both ways, interesting results...

- Again it read 3.4 at 70 degrees, good
- So I put a hair dryer on it and it went down to 1.0 fairly rapidly within 5 seconds, good
- Turned hair dryer on cool and it came up 2.5 fairly rapidly within 5 second, again good
- BUT the 2.5 to 3.4 at 70 degrees took several minutes, and that seems odd to me

I realize the temperature swings inside the air cleaner are minor and/or slow while driving, and the IAT is functioning within range and operating temperatures so it would be able to go with the flow per say, however I find it odd for it to be super slow in the 2500 to 3400 climb only.

PS: Orge, mine is original to the car (first time removed since assembly line) and it doesn't have a screen, just open windows.

[This message has been edited by Skybax (edited 05-18-2021).]

When the sensor is in the car with the engine running, air should be rushing over it fast enough so the response time is OK.

Sometimes air temperature can change fast. For instance, start and drive inside a closed parking garage, then drive outdoors into -30 °C weather. Very fast temperature change.

quote Originally posted by theogre: Note: When you drive then shut down, then sensor and air can get heat soaked for awhile and actually reads higher before whole engine bay cools. V6 w/ sensor in air cleaner doesn't get really hot. 87-88 w/ sensor In the Intake Manifold sees hot temps even at idle.

Even the stock V6 gets some sensor heatsoak.

To reduce the sensor heatsoak, I found it worthwhile to relocate the sensor to the water separator.

Modification of the sensor to work with a grommet, rather than 3/8" NPT threaded hole:


Installed in the water separator:


I would say that with the stock location, you could get about a 10°C rise in temperature measurement after a shutdown. With the modification, it's more like 3°C.

Eventually, I installed Rodney Dickman's cold air intake kit (essentially a corrugated tube that replaces the water separator).
http://rodneydickman.com/pr...o.php?products_id=70

A slightly longer tube with a sensor bung replaces Rodney's tube:




Similar heatsoak performance as with the sensor in the stock water separator.

[This message has been edited by pmbrunelle (edited 05-18-2021).]

Nice mod

quote Originally posted by pmbrunelle: When the sensor is in the car with the engine running, air should be rushing over it fast enough so the response time is OK. Sometimes air temperature can change fast. For instance, start and drive inside a closed parking garage, then drive outdoors into -30 °C weather. Very fast temperature change. ... Even the stock V6 gets some sensor heatsoak. To reduce the sensor heatsoak, I found it worthwhile to relocate the sensor to the water separator. ... I would say that with the stock location, you could get about a 10°C rise in temperature measurement after a shutdown. With the modification, it's more like 3°C.

While First 2 statements are True...

You think that mod matter just how? Because 10°C after shutdown is nothing and ECM doesn't care.
As soon as you start the V6 again, the V6 ECM sees very close to Ambient temp in seconds in the OE location.
The sensor is made to handle over 200°F 100°C because IAT/MAT often sees 150°F/65°C and more every time you run many engines...

ECM/PCM is Programed to have a sensor where they put them. You getting away moving IAT on V6 is just luck.
Run a scanner on 87+ Dukes and others and you see way higher temps even in Winter. And if you relocate to anywhere but in the Intake Manifold for Dukes, you will cause problems tripping various "codes" or not. I watch MAT go from > 150+°F to < 30°F and ping ponging all the way to work in winter trying to find Bogus DTC 45. MAT was cooked by a backfire but not dead and temp error flipped out ECM cause 45 at idle for a traffic light etc that keep engine at idle for awhile. After replacing the sensor didn't stop ping ponging but stopped 45 code. Why? read "Temperature Sensors Vs. Errors in Reporting" in my Cave, Sensors Quick Ref

And 87+ L4 and all V6 Fiero uses Same sensor. ACDELCO 213190, DELPHI TS10077, STANDARD MOTOR PRODUCTS AX1, etc.

Heat soaking a Thermistor after shutdown doesn't matter unless way over Operational Temps.

ECT uses same NTC sensor curve but expects to get heat soaked even higher temps as Coolant Flow stops but engine still have a lot of heat to dump.
IOW Engine Coolant at X°F w/ running engine gets Hotter After shutdown in some areas then finally cools. Is why many vehicles w/ coolant system problems "Boil Over" After Shutdown.
You may not see that happening on Dash Gauge or Scanners because location often matters and often need coolant flow to read right.