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Old 07-29-2003, 03:02 PM   #1
mdcatlin
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Question Factory Manifold Air Temperature sensor signal -- can it drive a gauge?

I recently hooked up the hosing & nozzles for soaking the intercooler down out of the windshield sprayer reservoir, but have to wonder when is the IC hot enough for this to be useful? Naturally I'd like to have a guage displaying air intake temp (post-boost) but don't want to open the can of worms associated with mounting a new sensor in a potentially pressurized tube.

In various WRX ECU Pinout profiles I've seen posted in forums & on personal websites (ie http://www.northursalia.com/m...ng/wrxpin.html ) , I see that pin B27 (brown wire) is described as "Intake air temperature sensor signal"

Does anybody know where this sensor is physically placed? Is it post-boost, post IC, or just measuring ambient air? Is it a PWM signal, or an analog voltage? Will the signal respond fast enough to temperature changes that I can use it in a closed-loop feedback control system to drive the sprayer automatically?

Any info or discussion would be great
Micah
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Old 07-29-2003, 03:12 PM   #2
mlambert
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John Felstead utilized IAT with his water injection system


....scanning for writeup....


here it is!

http://www.scoobynet.co.uk/bbs/threa...hreadid=233790
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Old 07-29-2003, 03:32 PM   #3
SysRq
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IAT sensor is an integral part of MAF sensor. In other words, it shows ambient air temperature which makes it pretty much useless for your purposes.

There's no manifold air temperature sensor.
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Old 07-29-2003, 04:34 PM   #4
vile
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not sure if it can drive a guage.....might be able too, cuz some of these a/f controller out there tap into these type of signals all the time

but for in intercooler spray kit.....it's not really neccessary to make the system so "smart"......i was going to build a controller which will monitor the ambient temp and boost, and based on that, it'll come on at X% duty cycles, then i realize, "hey, it's only an intercooler spray"

so instead of all that, i just made a variable duty cycle board, so that i can turn on the pump at anywhere from 25%-100% DC.

but one way of monitoring ambient air is just to pick up a set of thermocouple, run the signal thru a dac, based on that, you can then determine if the pump is on or not

or u can just buy a pressure switch which will turn on the pump at certain boost level
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Old 07-29-2003, 05:45 PM   #5
Red Rocket
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Quote:
Originally posted by SysRq
IAT sensor is an integral part of MAF sensor. In other words, it shows ambient air temperature which makes it pretty much useless for your purposes.

There's no manifold air temperature sensor.
This is correct.

Does anybody know who offers a guage and probe kit?

Thanks,

Kevin
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Old 07-29-2003, 07:42 PM   #6
mdcatlin
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Okay, it looks like John Felstead tapped & threaded a hole in his IC just before the outlet (by the BOV), and mounted a thermocouple to get a good reading on the actual charge air temp. I had hoped that such a sensor already existed and the ECU was using that...

Now I definitely do notice that on 105 degree afternoons, my boost will not go over about 8psi even near open throttle. If the ECU only knows ambient temp (from the integrated MAS Airflow / temp sensor) then it seems like soaking down the IC isn't even really going to work. The ECU will still sense high ambient temperature and will waste the boost, right?

Or is the boost limit I'm seeing a response to actual knock events rather than pre-emptively based on the temp? In that case I guess having a wet IC would truly prevent the knocks and let the ECU keep the boost rolling..
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