Thread: Is your IAT sensor hurting performance? Find out here!

Originally Posted by TDCRacing

good point...when looking at the iat with the different intakes i never went under ambient temps according to my digital climate control vs. my iat gauge...so i guess it is not under accurate if you know what i mean lol (not reading under the temps that it actually is outside)

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Originally Posted by TDCRacing

.....you know what i am going to go try that test with the ice water right now TO SEE HOW FAST THE REFRESH RATE IS and i will let everyone know how it turns out....the sensor is sealed so i dont imagine it will hurt it...the test will be with the car not running.... STANDBY!!!!!!!!!!

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Originally Posted by TDCRacing

OK SO.....

The conditions:

69*F ambient temps (according to the digital cc)
IAT sensor removed from the intake tubing
IAT temps were at a steady 85*F for at least 10 sec before test was done
Test was done with a glass of ice water (32*F)

THE TEST:

With car turned off and key in the run position and the hpt scanner right in front of me and the IAT readings being a steady 85* for at least 10 seconds i submerged half of the sensor in whe cup of ice water ( not up to the actual connector even though it is sealed tight ) and the IAT temps on the gauge instantly started going down in at least 8 deg decreasements and took aprox. 16 seconds to reach 35* and stayed there contiunesly even at 35 seconds.At that time i stopped counting.Test was over.


OK well this is a 50 degree difference in temps. A 50 degree drop in temps is easily seen if you have an under hood open cone and have been stopped for any short period of time and then start driving again.This is not to say that the air that the IAT sensor is reading is not the temp that is being shown but rather a delayed measurement instead.



I dont think that there is a way to tell if the IAT sensor reacts quicker/slower to a majior temp change compared to a minor temp change.I would think that it's reaction time would be the same.


So yes the IAT sensor is delayed in reading the actual temps that are present.

Now a question: Could this delay purposely be made like this because the pcm would not be quick enogh to make instant changes like that? ex. to compensate for timng ect due to the cooler air temps.....

Just a thought

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Originally Posted by Reptile

So now what can we assume by a better IAT sensor....perhaps an almost instant drop directly to say 32 degrees instead of over 16 seconds?

I'm not sure that the PCM wouldn't be able to keep up, keep in mind that what you see on the scan data is what the PCM is reading as input from the sensor. Given how fast it reads O2 values and degrees of timing, I would doubt it couldn't keep up with temperature change which isn't near as drastic.

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Originally Posted by Reptile

Did you happen to count how long the interval was in between temperature changes to figure out the refresh rate?

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Originally Posted by SyntheticShield

This is extremely good info guys. Great work and even better information. It times like this that my joy abounds even more that this community was formed.

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Originally Posted by TDCRacing

1. Exactly!


2. Ok well not saying the GENERAL SPEED that the pcm is capable of is not keeping up with the temp changes (good example with the 02's) but more leaning twards it was not designed to,therefore getting a more accurate IAT may not matter.It may not be the IAT that is the problem after all.In other words it may be possible that the sensor is not the problem but how fast the pcm was DESIGNED to read the IAT temps may be lacking.


Or ...... I could be totally wrong and we may just need a better IAT sensor....Its a 15.00 part....It cant be made to meet to high of standards

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