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open-element IAT sensor for 1JZ/2JZ

IAT Sensors standalone

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#1 JimmyHoffa

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Posted 03 October 2012 - 01:05 PM

I'm looking for an open-element IAT sensor that will fit in place of the stock JZ IAT sensor. I don't know why the dummies at Toyota used a closed element IAT, but my intake mani heat soaks if I sit and idle and the IAT heat soaks too showing upwards of 70C as my intake air temp when I'm sure it's nowhere near there. Then takes a while of driving for the IATs to come down to a reasonable value. It kinda helps on a boosted car to have fast response on something like IAT since at higher boost levels high intake temps can become a problem pretty quickly.

"JZXP - we get death threats" -Rayray
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#2 Foompla

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Posted 03 October 2012 - 04:40 PM

70C wtf? check out nissan's brah.

anything with a map sensor



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#3 Guest_gameface_*

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Posted 03 October 2012 - 07:25 PM

I have the same problem with a gm iat sensor(open element) although probably not the same extent, once I start driving it clears up. This is also with water to air intercooler where even at idle the air should be getting cooled seeing how its constantly circulated with fan running on the heat exchanger. I don't really like the gm iat but haven't experimented with others either. I have doubts about its reaction time.

I set MAT correction to start at 55c something like 15% at 70c figured also helps during extended abuse on the engine when iat will really pick up also. Pre det no thx.

#4 Kyle

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Posted 04 October 2012 - 03:50 AM

Get bung and weld in charge piping right after intercooler?

I've been wondering how the stock ecus work with this for awhile now. I monitor that shit with the emanage and on my non vvti shit temp quickly shoots sky high. With my vvti shit the iAT is in the maf and the temp is pretty consistent with what ambient temp is. I know that after being compressed and ran through heatsoaked piping it isn't the same as the ambient temp and I also know that on the non vvti setup it isn't 200+ degrees either. Since I'll probably be strictly vvti here shortly I've been thinking of using the MaF in blow through fashion since I'm mostly fueling by pressure anyway and this way I'll get a correct-ish reading. Guess I can log timing changes as well.

Let us know what you go with.
Maybe it's a cultural thing? I mean, we saw the British coming. India, they did not.

#5 JimmyHoffa

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Posted 05 October 2012 - 08:42 PM

I'm likely going to go with a welded bung in the IC piping just before the TB and usd a GM open element sensor from an old 80s/90s Buick, Pontiac or Chevy. Gotta get this sorted before I dyno because I don't trust the stock IAT. On most of my data logs it's reading lower temp under boost doing WOT pulls than at low load cruise on the highway, and that's lower than idle air temps by like 20 degrees. I assume since the sensor is getting less manifold heat soak and actually seeing enough air to effectively read at WOT.

"JZXP - we get death threats" -Rayray
-1987 AE86 Corolla with 20 valve swap SOLD
-1985 MX73 Cressida 1.5JZ Holset HX35 & MS3X
Toysport and 935 Motorsports suck. Don't buy from either.


#6 JimmyHoffa

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Posted 22 November 2012 - 06:54 AM

I got a GM open-element IAT and aluminum bung from DIYAutotune. I'm going to disconnect the stock intake manifold temp sensor (fucking thing doesn't measure actual IATs for shit), and run the GM sensor in my intake piping before the TB.

To show how bad it really is, driving around with the ambient temp at -2 degrees C (the car fucking loves this weather) the stock IAT reads around 25-30 degrees C. At idle in the same weather, around 50 degrees C...

"JZXP - we get death threats" -Rayray
-1987 AE86 Corolla with 20 valve swap SOLD
-1985 MX73 Cressida 1.5JZ Holset HX35 & MS3X
Toysport and 935 Motorsports suck. Don't buy from either.


#7 Kyle

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Posted 23 November 2012 - 05:27 PM

Move to jz/uz tech section? Let us know the difference on the temps. I've been thinking about this myself lately, how my emanage logs would be damn near all the same high ass temp catching heat soak from the engine and how IAT corrections would be fairly inaccurate. Been thinking of doing blow through maf to change this myself.
Maybe it's a cultural thing? I mean, we saw the British coming. India, they did not.

#8 JoeTheHook

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Posted 23 November 2012 - 05:37 PM

Im interested also post up results
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#9 Guest_FrozenChosin_*

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Posted 25 November 2012 - 07:18 AM

If the 1J has a CSI [Cold Start Injector] you can pull it and make a plate out of something that's resistant to temp change [like phenolic resin] and mount the sensor in that. Should slow down heat soak. Just another option.

#10 JimmyHoffa

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Posted 25 November 2012 - 07:26 PM

^ JZs do not have cold-start injectors.

The stock sensor is a closed element, so the entire brass cap heats/cools too slowly to give an accurate real-time reading, especially doing pulls when your intake air temp might go from 50F to 150F in a matter of a few seconds. The thermistor in the stock sensor is also not thermally isolated from the mounting plug/body. The GM sensor I got uses an open-element, so the thermistor sits in the middle of a plastic cage, not really hard mounted to anything thermally conductive (other than the wires that run to it), so it will give a lot more accurate reading of real-time intake air temp.

Open element
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closed element crap
Posted Image

"JZXP - we get death threats" -Rayray
-1987 AE86 Corolla with 20 valve swap SOLD
-1985 MX73 Cressida 1.5JZ Holset HX35 & MS3X
Toysport and 935 Motorsports suck. Don't buy from either.


#11 JoeTheHook

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Posted 25 November 2012 - 07:36 PM

I'm prob going to end up welding a bung in front of the tb. But with stock ecu? Gm reads the same voltage?
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#12 JimmyHoffa

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Posted 25 November 2012 - 10:10 PM

This is for standalones only. With the MS I can use pretty much any IAT sensor, I just have to calibrate based on three known temp vs resistance points (I usually calibrate with an ice bath, boiling water, and room temp, check resistance at those points, plug into TunerStudio, and voila).

The stock ECU is expecting to see the numbers that the stock sensor is going to read, even if they're not realistic intake air temp numbers. If anything, doing this with a stock ecu would cause problems and likely not yield any benefits.

"JZXP - we get death threats" -Rayray
-1987 AE86 Corolla with 20 valve swap SOLD
-1985 MX73 Cressida 1.5JZ Holset HX35 & MS3X
Toysport and 935 Motorsports suck. Don't buy from either.


#13 Guest_Radial_*

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Posted 26 November 2012 - 02:31 AM

Hmm...this is not good, as i'm planning on using that stock IAT for my setup. Maybe need to reconsider that.... funny thing this never is almost never mentioned...even at BIG hp projects.

#14 JimmyHoffa

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Posted 28 November 2012 - 06:14 AM

I know a few guys who have told me not to worry about the IAT signal being representative of reality and to just use it as a reference. Eg if it usually sits at 50 deg. C in the summer and it hits 75 or 80 to start worrying about pre-ignition, but I would rather spend 30 bucks on a sensor that will read accurately without much lag and allow me to run IAT based fueling and ignition correction so I can just keep mashing the pedal and not have to worry too much about shitting out my pistons.

"JZXP - we get death threats" -Rayray
-1987 AE86 Corolla with 20 valve swap SOLD
-1985 MX73 Cressida 1.5JZ Holset HX35 & MS3X
Toysport and 935 Motorsports suck. Don't buy from either.


#15 Guest_FrozenChosin_*

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Posted 28 November 2012 - 10:01 AM

Interesting; I gotcha.
Does the GM sensor use the same signal [as temp goes up resistance goes down]?

How's it working? Do you still have heat soak with it?

#16 MX83MISSILE

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Posted 29 November 2012 - 07:04 AM

I'm running a map ecu2 and instead of the me2 IAT sensor and intake air temp compensation I run a early 90's Corolla IAT on the stock vvt-i ecu and disable the me2 intake air temp compensation . This setup works well as it reads the same resistance as the stock IAT in the maf and it plugs into a rubber grommet in the intake pipe before the turbo .
Posted Image
mx83 cressida 1jz-gt vvt-i 5spd
fx16 20v 5spd
Pete, MX83MISSILE

#17 JimmyHoffa

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Posted 29 November 2012 - 08:57 AM

I'm 95% sure the scaling of the thermistor range is different, so it's not going to be interchangeable, nor would you want to try it with a stock ecu.

I won't actually have any results until spring. My car is away for the winter since it's snowing and the roads are covered with salt. I'm sure that it will work as planned, or at least 95% better with this IAT before the TB than the stock sensor in the intake mani.

"JZXP - we get death threats" -Rayray
-1987 AE86 Corolla with 20 valve swap SOLD
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Toysport and 935 Motorsports suck. Don't buy from either.


#18 Guest_Radial_*

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Posted 29 November 2012 - 11:10 PM

I'm running a map ecu2 and instead of the me2 IAT sensor and intake air temp compensation I run a early 90's Corolla IAT on the stock vvt-i ecu and disable the me2 intake air temp compensation . This setup works well as it reads the same resistance as the stock IAT in the maf and it plugs into a rubber grommet in the intake pipe before the turbo .
Posted Image


Maybe i'm just being stupid resonating about this, and I very might be terribly wrong. but isn't half the point of an IAT is to compensate for hot air entering the Intake manifold.?
So by measuring the intake temp on the turbo, you are missing the heat buildup in the compressor in different attitudes and temps, and the cooling/heating in the IC in different speeds.....in other words, your temp measurements would be kinda useless in front of the turbo?

I know MAF's work that way, but they compensate for that by measuring the actual volume of air entering the turbo too.. that makes it more accurate as long as the system behind is within standards.

#19 JimmyHoffa

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Posted 30 November 2012 - 10:16 AM

A lot of MAFs have the IAT built in. This does completely disregard the fact that your actual IATs might go up or down depending on boost and how much cooling your IC does. The ideal place for the IAT is in the intake manifold or just before the TB. You want the temperature of the air that is entering the ports as close as is reasonably possible to the ports without the sensor heat-soaking or causing restriction/turbulence to the air flow.

"JZXP - we get death threats" -Rayray
-1987 AE86 Corolla with 20 valve swap SOLD
-1985 MX73 Cressida 1.5JZ Holset HX35 & MS3X
Toysport and 935 Motorsports suck. Don't buy from either.


#20 MX83MISSILE

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Posted 01 December 2012 - 07:15 AM

No vvt-i jz-gte's came with IAT sensors in the manifold like non vvt-i jz-gte's did so I used this sensor to satisfy the IAT signal requirements of the stock ecu . I have used this sensor for about six months now with no trouble codes and no tuning issues . I use Toyota Techstream to monitor obd data and this IAT sensor's siginal is dead nuts the same as the IAT in the stock maf . When I first installed the ME2 I used the resistor it came with to clamp the stock IAT signal , welded a bung just before the throttle and installed the ME2 IAT . It ran fine but it heat soaked and had a fit on hot and cold starts due to bad fuel trims it built because of the differential between coolant temp and intake air temp . I than moved the ME2 IAT to the intake pipe and it cut the trouble almost in half . I had a Corolla IAT around the shop so for shits and giggles I tried it and it has bean 100% like stock . I now have it running with no maf , the Corolla IAT in the four inch intake pipe before the turbo with the ME2 IAT compensation disabled , no trouble codes and good fuel trims .
mx83 cressida 1jz-gt vvt-i 5spd
fx16 20v 5spd
Pete, MX83MISSILE




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