Where to install IAT sensor post-TMIC?

[AZPete]

I'd like to know the temp of the post-TMIC air, so where did you install your sensor?

[SixStar]

Always as close to the throttle body as possible.

[Hindsight]

You can add a bung in one of your intake manifold runners and put an IAT sensor in there. I have an AWIC and I put one temp sensor in the post-plenum of it, and another one in the intake manifold runner. The one in the runner is for my ECU for speed density mode (which I haven't switched over to yet), and the one in the plenum is for my dual-zone IAT gauge (the pre-sensor is in the pre-plenum of the AWIC core).

[Mitch Wright]

I have mine mounted in the bottom TMIC tank about 4" from the Throttle body on the right side.

[Sgt.Gator]

Folks should be aware that the IAT in a aluminum intake manifold is generally discouraged for an SD only tune. The reason being the aluminum manifold will heat soak and hold quite a bit of heat for awhile. That heat soaks the entire sensor which again takes awhile to cool down. The results are IAT sensor temps reading too high, the ECU thinks the air temp is high (less dense) so compensates by leaning out the fueling, Too lean AFR = boom.

It's not a concern with a hybrid MAF-SD tune.

On my 2005 STI race car build I originally had planned on putting the AEM IAT sensor in my STI intake manifold but Cobb Surgeline strongly advised against it. They told me to move it to my FMIC piping close to the throttle body. The FMIC piping is very thin and will cool quickly when air is moving thru it once the engine starts running. Even then they told me a wideband AFR gauge or data display is highly recommended and to advise drivers first pulling out of the pits onto the track to keep an eye on the AFRs for a lap or too.

There was no room right in front of my throttle body and in my case moving a bit upstream put the IAT sensor directly above the turbo which I figured was a bad idea if I'm avoiding heat soak sitting in the pits/paddock. So I moved it further upstream, basically to the same engine bay location as the OEM MAF-IAT would be located. It looks like the coolest place in the engine bay for it to go.

I still have an unused 1/8" NPT hole available in my STI intake manifold so I may put an IAT sensor there just to log the delta between the two sensors for curiosity. I also have 3 x 1/8"NPT bungs available right behind my air filter I may use to compare intake temps at the filter to intake temps at the throttle. And if I make airflow changes in the engine bay if it affects the air filter intake temps. You can see the open available hole in the intake and the three 1/8" bungs in the coupling behind the air filter in the second image.

65920......65921

[AZPete]

Mitch, did you have to weld a bung on your TMIC, or just drill and tap?

[Mitch Wright]

Pete,

I just drilled and tapped the sensor into the tank at first and it was fine. But it is only maybe .100 of material in the bottom tank you have to work with which made me nervous and ended up welding bung for piece of mind.
Corbin Johnson sells a kit with a really nice wiring pigtail the sensor and bung so it is a plug and play for $90.00.

[AZPete]

I have mine mounted in the bottom TMIC tank about 4" from the Throttle body on the right side.

Mitch, I pulled my donor TMIC off to take it a shop to have an aluminum bung welded into the bottom, but (oh no) it's black plastic.
66270
Now what?

[Mitch Wright]

Well that is a problem, I have an older STi intercooler.

I did find a couple of different Intercooler to Throttle body silicone hoses that have a bung for the air temp sensor. I just don't recall where/who had them, it might have been Subimods.

[AZPete]

Thanks, Mitch. I'll go hunting for the solution.

[Mitch Wright]

http://www.jti.uk.com/wp-content/uploads/Joiner-with-sensor-fitted.jpg
I found a hose like this available from a US tuner/supplier but don't recall who and my search has come up blank.

[iblackwe]

Folks should be aware that the IAT in a aluminum intake manifold is generally discouraged for an SD only tune. The reason being the aluminum manifold will heat soak and hold quite a bit of heat for awhile. That heat soaks the entire sensor which again takes awhile to cool down. The results are IAT sensor temps reading too high, the ECU thinks the air temp is high (less dense) so compensates by leaning out the fueling, Too lean AFR = boom.


How would this respond to an intake mounted on phenolic spacers? As far as I know these will help block the transfer of heat from the engine block into the intake manifold.

I currently have one installed in the long runner where the brake booster once was and I wondering if I should be moving it.

Thanks
Ian

[Sgt.Gator]

I don't know. Are you running a pure Speed Density tune? If you still have a MAF and are running MAF or Hybrid MAF/SD it's fine.

[iblackwe]

If anything it will be a combination as I have kept the MAF. This is off topic but how does everyone plumb in their IAT sensor into the original ECU? I was thinking of re-using one of the TGV position sensors and rescale the input reading to correspond to the IAT algorithm. There is the other option of plumbing it into the old EGT wiring as that has been removed from the up-pipe.

[SixStar]

If you're keeping the OEM IAT in the MAF then steal from another 0-5 as you mentioned.

On my car I just used the OEM IAT wiring to a GM/AEM IAT and rescaled it.