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IAT RE-relocation

Old 07-12-2019, 09:46 AM
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IAT RE-relocation

Had a quick question. I believe I've seen a few people do this and was curious as far as results. My car was originally a MAF setup but I switched over to MAP when I upgraded to an EBL. I relocated the MAT from the plenum to the air snorkel and went to a cage style IAT sensor. This location isn't as pone to heatsoak as the plenum however, the TPI snorkel being right above the radiator will still heatsoak the sensor at low speeds or when the vehicle is not moving. Even doing a few laps on test pulls, while pulling over for 3-5 minutes to write and flash a new tune, at key-on the IAT will report a temperature of 115+F and then gradually settle back down as the vehicle is driven.

I am getting ready to do a ram air through bumper setup and was thinking of relocating the sensor again to one of the air boxes. What would be effective and practical: Towards the bottom of the box near the nose or closer to the top of the box near the filter? I'm thinking that placing the sensor too low may make it susceptible to mechanical damage from rogue rocks or sticks.
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Old 07-12-2019, 12:47 PM
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Re: IAT RE-relocation

I have wondered this: Relocation of the IAT or putting resistors in their place to show cooler air doesn't help.

You complain of heat soak, but the heat is soaking the air and is reflecting the temp of the air the engine is getting. Why is it better to lie to the computer and take a reading where the air is cooler? For true optimal tuning, wouldn't it be ideal to have an Air Temp Sensor in the actual intake runner (impractical I know)? It seems keeping it in the plenum gives the most accurate reading possible.
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Old 07-12-2019, 01:16 PM
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Re: IAT RE-relocation

Here's something to think about. If the reading in the aircleaner is more desirable than the reading in the plenum, why didn't GM put the sensor in the aircleaner? They obviously understood it was possible, all the six cylinders had the sensor in the aircleaner. Why would they produce two systems, and different sensors, and deal with the complexity, when they could have just put the sensor in the aircleaner on everything?

On TPI it's not Iat, it's Mat.
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Old 07-12-2019, 01:22 PM
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Re: IAT RE-relocation

Per the original post, the sensor is heatsoaking only at low or no movement because it sits directly over the top of the radiator. Not because the actual air going into the engine is that temperature. It's not "lying to the ECM".

TPI itself has nothing to do with the style of sensor. On MAF setups it was located in the plenum purposely to measure heatsoak. That's why it was referred to as an MAT. Its only purpose was to enable the EGR. On MAP setups, it was relocated to the air cleaner lid and actually influenced fueling calculations. It was then referred to as an IAT.
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Old 07-12-2019, 01:36 PM
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Re: IAT RE-relocation

I used to run that setup. I used ducting from the grill openings right to the bottom of the gutted filter panel. I ended up extending the IAT wiring, and I ran it in to the side of the ducting. It was protected from debris, and still did a good job of picking up temps. It was halfway up between the openings in the grille and the filters. I will say, that setup did a HELLUVA job keeping the air temps cool. I could go on an hour drive in 70 degree temps, and the plenum would be cool to the touch right after driving. It gets the filters pretty nasty QUICK.

I understand the difference in IAT and MAT, because I'm also living the EBL life. TPI only used the MAT for EGR, BUT the EBL uses it properly....as an IAT.

Put it somewhere in front of the filters. It'll be fine. Not like the sensors are terribly expensive. In the grand scheme of things, the IAT/CTS table will never be 100% perfect. Location of it is somewhat important, but I wouldn't lose too much sleep over it.
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Old 07-12-2019, 01:42 PM
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Re: IAT RE-relocation

Originally Posted by FireDemonSiC View Post
On MAP setups, it was relocated to the air cleaner lid and actually influenced fueling calculations. It was then referred to as an IAT.
Temperature relates to density, so no doubt influences fueling calculations.

I have both scanning software for the TPI's and my Challenger will display this information on the dash. Both exhibit similar bahvior... so did my TTA and my Mustang that I also used scanning on to read sensor data. The air is cooler at entry and temp will go up soem before entering the combustion chamber.

So to clarify, I am asking... why isn't it better to have it as close to the combustion chamber as possible? The sensor is reading the temp of the air in the area the sensor is... when air velocity goes up, temp drops quickly., but until then the slower moving air is affected by heat soak. This is the reason for ice bags at the strip.

What is the benefit at reading it near the filter rather than in the plenum? In a general sense, not just in the way the TPI was set up.
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Old 07-12-2019, 01:46 PM
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Re: IAT RE-relocation

Originally Posted by RJ IROC View Post
I used to run that setup. I used ducting from the grill openings right to the bottom of the gutted filter panel. I ended up extending the IAT wiring, and I ran it in to the side of the ducting. It was protected from debris, and still did a good job of picking up temps. It was halfway up between the openings in the grille and the filters. I will say, that setup did a HELLUVA job keeping the air temps cool. I could go on an hour drive in 70 degree temps, and the plenum would be cool to the touch right after driving. It gets the filters pretty nasty QUICK.

I understand the difference in IAT and MAT, because I'm also living the EBL life. TPI only used the MAT for EGR, BUT the EBL uses it properly....as an IAT.

Put it somewhere in front of the filters. It'll be fine. Not like the sensors are terribly expensive. In the grand scheme of things, the IAT/CTS table will never be 100% perfect. Location of it is somewhat important, but I wouldn't lose too much sleep over it.
Thanks for your help once again RJ. That is exactly how I plan to set it up!
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Old 07-12-2019, 01:57 PM
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Re: IAT RE-relocation

Originally Posted by Drew View Post
Here's something to think about. If the reading in the aircleaner is more desirable than the reading in the plenum, why didn't GM put the sensor in the aircleaner? They obviously understood it was possible, all the six cylinders had the sensor in the aircleaner. Why would they produce two systems, and different sensors, and deal with the complexity, when they could have just put the sensor in the aircleaner on everything?

On TPI it's not Iat, it's Mat.
Well gee... based off that logic you would have to think everything on the Thirdgen was perfectly optimized. Which it wasn't.. far from it on so many levels.

All Six cylinders did not have it in the Air Cleaners by the way. Near it sure, but not in it.
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Old 07-12-2019, 02:02 PM
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Re: IAT RE-relocation

Originally Posted by FireDemonSiC View Post
TPI itself has nothing to do with the style of sensor. On MAF setups it was located in the plenum purposely to measure heatsoak. That's why it was referred to as an MAT. Its only purpose was to enable the EGR. On MAP setups, it was relocated to the air cleaner lid and actually influenced fueling calculations. It was then referred to as an IAT.
Witch Doctor Voodoo aftermarket ECM setups aside, MAF/MAP makes no difference. GM put it where they did on TPI for a reason.

Originally Posted by FireDemonSiC View Post
I upgraded to an EBL.
I missed this squib, so nvm if your aftermarket witch doctor, voodoo, faith healing ECM requires something specific.
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Old 07-12-2019, 02:03 PM
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Re: IAT RE-relocation

Originally Posted by KyleF View Post
Well gee... based off that logic you would have to think everything on the Thirdgen was perfectly optimized. Which it wasn't.. far from it on so many levels.

All Six cylinders did not have it in the Air Cleaners by the way. Near it sure, but not in it.

Shut it fool. I have zero time for your stupidity.
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Old 07-12-2019, 02:20 PM
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Re: IAT RE-relocation

Originally Posted by Drew View Post
Shut it fool. I have zero time for your stupidity.
Mine? You are the one that thinks 80's technology is 100% optimized.

Not to mention your statement:
Originally Posted by Drew View Post
all the six cylinders had the sensor in the aircleaner.
Which they were not. Again I say, close, but in the tube. Also, Air Cleaner is two words.

So back to someone who make actually know the answer. What is the advantage to having the IAT reading the cooler air near the filter rather than reading the air temp closer to where it will enter the combustion chamber?

Last edited by KyleF; 07-12-2019 at 02:27 PM.
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Old 07-12-2019, 02:28 PM
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Re: IAT RE-relocation

IAT/MAT is only really relevant when running in open loop in any event, otherwise, the O2 sensors are going to correct fuel mixture (injector pulse width) when in closed loop. No matter where you put it, it really isn't going to have that much (if any) of an affect on performance. All the 'magic chip' (inline resistor on IAT/MAT sensor) hype aside, if changing the value of one sensor, would yield 50 more horsepower, and 10 mpg better, it would have come that way from the factory.......
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Old 07-12-2019, 02:30 PM
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Re: IAT RE-relocation

Originally Posted by KyleF View Post
Mine? You are the one that thinks 80's technology is 100% optimized.
Did I say that, or are you putting words in my mouth?

Originally Posted by KyleF View Post
Not to mention your statement: Which they were not. Again I say, close, but in the tube. Also, Air Cleaner is two words.
What do you call the piece of plastic or steel that houses the air filter? If attacking my spelling or grammar helps you compensate for being a buffoon, good for you.

Originally Posted by KyleF View Post
So back to someone who make actually know the answer. Why is the advantage to having the IAT reading the cooler air near the filter rather than reading the air temp closer to where it will enter the combustion chamber?
"Why is the advantage" LOL And you want to be the grammar police?

See ya around Kyle.
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Old 07-12-2019, 02:35 PM
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Re: IAT RE-relocation

Originally Posted by ploegi View Post
IAT/MAT is only really relevant when running in open loop in any event, otherwise, the O2 sensors are going to correct fuel mixture (injector pulse width) when in closed loop. No matter where you put it, it really isn't going to have that much (if any) of an affect on performance.
Thanks


Originally Posted by ploegi View Post
All the 'magic chip' (inline resistor on IAT/MAT sensor) hype aside, if changing the value of one sensor, would yield 50 more horsepower, and 10 mpg better, it would have come that way from the factory.......
Yes, I know of the resistor and relocation kits that popped up over the years that were snake oil. But to the last statement... there are a few pulley/tune or boost controlled combos that you would have to make an exception for.
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Old 07-12-2019, 02:40 PM
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Re: IAT RE-relocation

Originally Posted by Drew View Post

What do you call the piece of plastic or steel that houses the air filter? If attacking my spelling or grammar helps you compensate for being a buffoon, good for you.
Air Cleaner Housing, Air Cleaner Assembly? Maybe Air Filter Housing? Still, all V6 cars did not have them inside said housing. Some were in the tube near it.
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Old 07-12-2019, 02:41 PM
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Re: IAT RE-relocation

I stopped replying to anyone after RJ because I had the overwhelming sensation that this thread was fast track on the way to turning into a crapshow. I can't say I was wrong
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Old 07-12-2019, 02:47 PM
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Re: IAT RE-relocation

EBL flash moves it to the filter intake area on the TPI - its all in the tune guys.
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Old 07-12-2019, 02:51 PM
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Re: IAT RE-relocation

Originally Posted by FireDemonSiC View Post
I stopped replying to anyone after RJ because I had the overwhelming sensation that this thread was fast track on the way to turning into a crapshow. I can't say I was wrong
My sincerest apology for trying to help you.
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Old 07-12-2019, 03:03 PM
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Re: IAT RE-relocation

Originally Posted by Drew View Post
My sincerest apology for trying to help you.
Case and point
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Old 07-12-2019, 03:19 PM
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Re: IAT RE-relocation

Originally Posted by FireDemonSiC View Post
Case and point
All I said was to think about why professional engineers designed a system the way they did. I already admitted I missed the part about the aftermarket ECM, and to disregard my statements if they don't apply. Anything that happened after that, I can't take responsibility for. Blame whoever you like, believe whatever you like, but I was trying to be helpful. Sorry if that offended you.
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Old 07-12-2019, 03:43 PM
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Re: IAT RE-relocation

I can assure you that I'm not one of the one's on this post that took offense
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