IAT heat soak

[WHYTRYZ06]

Thank god for a0014...lol

[mistermike]

I believe that until we can accurately measure the intake aircharge near the valve, with a sensor that isnt prone to inaccuracy due to its own body becoming heatsoaked, we will be constantly chasing our tail. Until then we have the bias tables to estimate the temp as well as misreporting sensors. No wonder we end up pulling our hair out & using what we can to get as close as possible.

Well, I'm almost there, with a cruel twist. I'm running a Starr supercharger setup with an IAT sensor literally stuck in one of the intake ports. The bad news is that it's a brass threaded sensor screwed into an aluminum manifold. I never see anything below about 115 F and to add insult to injury, as with any F/I setup, I'm constantly "modulating" my IAT with the heat generated by the compressor. Stuck in traffic, fuhgettaboutit. DELCO is probably the only guy equipped to make sense of something like this, since he has the same setup, and I believe he invented the A0014 table anyhow.

[98 tigershark]

Place the sensor by the air filter if you have not already as the motor super heats the motor compartment air and the air by your filter is the accurate intake air temp no mater how you look at it.
98 tigershark

[mistermike]

Place the sensor by the air filter if you have not already as the motor super heats the motor compartment air and the air by your filter is the accurate intake air temp no mater how you look at it.
98 tigershark

The combustion chamber is a long way from the air filter. There is ample opportunity for the temps to change along the way. The air/fuel molecules detonating in the combustion chamber don't care a bit what the temperature used to be when they started their journey.

[redhardsupra]

The combustion chamber is a long way from the air filter. There is ample opportunity for the temps to change along the way. The air/fuel molecules detonating in the combustion chamber don't care a bit what the temperature used to be when they started their journey.

absolutely correct!

[98 tigershark]

I believe the question was IAT heat soak.
What you are talking about is an entirely different issue. If you want the correct air temp that the car is taking in then the sensor needs to be next to the air intake filter. The molecule thing sounds impressive and is something to consider in the start up table but not the IAT as the question again was heat soak and the IAT sensor, right. After all the IAT temp is the IAT temp not the valve temp and the density of molecules as once started the IAT has priority on most all 1997 to 2005 PCMs
98 tigershark

[joecar]

The PCM is using IAT (and other values) to estimate how much air just went in... so while the molecules themselves don't care what temperature they started with (at the IAT sensor, a long way away from the CCs), the number of molecules is dependent on the IAT (and a few other things).

[Chevy366]

Why not have dual IATs then , one at the filter and then one at TB ?
Like I have seen , some older models have the IAT in the intake manifold behind the TB , couldn't get much better than that , but yet they moved the IAT out to the filter location .

[redhardsupra]

yes, you can fix heatsoak, but in the process completely lose the point of having an IAT. you're supposed to be estimating temperatures of the airmass in the intake, not air outside, that's just called the ambient thermometer

[98 tigershark]

Joe and Red hard Supra are right I think. The IAT on most 1997-05 PCMs is to do a few things and does have a high priority in the computations. I thought heat soak was when the O2 sensors are to warm to accurately communicate with the PCM. The IAT/ETC AND THE BARO blend determine the amount of air density entering the cylinder or known as the charge temperature.
98 tigershark