Monday, January 26, 2015 - 08:05 pm, by: Brett Harrison(Bretto)
I'm aware the IAT in the standard location on the manifold gets very heat soaked and generally sends misleading information to the ecu in regards to the actual intake temps. It's also a very slow sensor in that it takes several minutes or more for it the change to changing temperatures. So once heat soaked can have marked effects on ignition advance / fuelling despite possibly cool intake temps.
Just wondering if anyone else has changed there stock sensor, or relocated it elsewhere. I was thinking just before the throttle body.
Tuesday, January 27, 2015 - 05:35 am, by: Blake Gloyn(Blakenz)
you are exactly right. The IAT v ignition table in the ECU robs tens of kWs once the plenum is heat soaked. It certainly gives a wide band of protection, but kills performance. I think anywhere between the intercooler and the throttle body will be fine. Sure, you are still limited by the speed of the factory sensor, but i think this drawback will be a lot less exposed if it was relocated as discussed. If you get an alloy threaded boss made, to relocate(and perhaps a plug for the hole in the plenum,) Id be keen to have one done at the same time. So would a couple of mates, actually. To give you an idea of potential, my car ran a heat soaked low 12 sec pass at 114mph with intake peak of 69 degrees C, and ran over 120mph with inlet air peak of 29 degrees.
Tuesday, January 27, 2015 - 10:27 pm, by: Brett Harrison(Bretto)
Blake, yeah anywhere in the IC piping I guess. Possibly further towards to IC than the throttle body to reduce heat soak, or chance of. I believe the vvti runs the iat in the AFM, so the same setup as the 1UZ. This could also be a possibility for our cars, would be much easier and cheaper to just simply place the IAT inside the air box.
Out of interest the engine coolant sensor, runs the same resistance and readings as the IAT, so at roughly 20 deg C, it's reading around 2kohm.
Boris the 1J uses an old design closed element sensor, newer cars have open element. Closed element, takes a lot longer to respond to changes in air temp. The airflow in the manifold doesn't compensate, poor location possibly but largely just becoming heat soaked would be my guess.
Blake, I would possibly just leave std sensor in place, unplugged and get a new sensor, they are fairly cheap.
Tuesday, January 27, 2015 - 10:37 pm, by: Blake Gloyn(Blakenz)
mine is a Apexi power FC, which uses all the factory sensors. The sensor takes AGES to correct. One I was at the drags, and the car(which had a best of 117mph) was going one second slower on each pass i.e. 14sec, 15 sec, 16 sec. Inlet temps were 70 degrees. Hot day/under bonnet heat soak. I drove home, cruising gently. it took 40 minutes before the IAT dropped down to 40 degrees! I think it is most likely a slow reacting sensor, PLUS the alloy acting like a giant heat sink and heating up the sensor. Any tuner installing a more modern computer ALWAYS say they don't want to use the factory IAT sensor, or its current location.
Wednesday, March 11, 2015 - 03:57 pm, by: Ricky Liddy(Padrickz88)
If anyone does this keep us updated on the results.
In terms of relocating, would it be easier to weld a bung to a piece of plate (think of how an oxygen sensor looks) then get another plate welded into the intercooler piping and then maybe put some teflon plate in between to stop heat transfer to the sensor, but would still be getting a fairly accurate reading.
I've seen people use it for home made style manifold insulators so it may work right?
Does this even sound possible? or am I dreaming that it would be that easy?
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