Relocating IAT sensor - S2KI Honda S2000 Forums



Relocating IAT sensor

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Old 09-22-2010, 12:55 PM   #1
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Default Relocating IAT sensor

Guys, i run a pretty lowly 7psi CTSC+AC+bolts+VAFC2 (mods in my signature). I was thinking of relocating my IAT sensor. BTW the AFR is fine.

Don't shoot me down in flames but...

I know that in later models, Honda relocated the IAT sensor into the intake tract. The problem is when i monitor the IAT values if the car has been sitting for a while (5mins) it gets heated up by the intake manifold in some instances it hits mid 60c - this is when its around 15-20c ambient outside too.

When on the move it takes a wee while to drop down (hovers around 50c when pootling around slowly) but i believe the stock ECU retards timing if above 45c in WOT? (which it can in some instances), however the temps do drop down when i put my foot down.

Just wondering if its worth relocating and capping off?, however i dont know if its feasible as Honda would have likely tested and coded in the high temp values into the ECU map??

Just seems a bit of a design fault and not a 100% representation of true air temp.

Thanks.
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Old 09-23-2010, 09:01 AM   #2
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Old 09-23-2010, 09:14 AM   #3
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this one to me is a tough answer.

if you move it, then you dont know the true temp of the air going into the combustion chamber. having it on the intake manifold, or the oven as i like to joke, tells you how hot the air is right before it goes into the combustion chamber. yeah the sensor gets hot, but thats because the intake mani is hot, and just like the sensor is being heated up, so is the air, its an interheater so to speak.

so your choice, move it and see lower numbers, or keep it there and see higher numbers, but in both cases, once car is tuned for that location, its gonna work the same. stock ecu i def wouldnt move it.
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Old 09-23-2010, 11:18 AM   #4
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Yes, relocating the AIT with FI is a great thing if you can retune correctly, in your case you cannot so this will really F things up if you try it.

If you get an AEM you may want to do it but with a piggy back or KPRO you will be waisting your time. Even the AEM does not have a good algorithm for fuel trims based on the AIT, to do it right you would need a better ECM like a Motec.
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Old 09-23-2010, 12:16 PM   #5
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I wouldn't bother with it imo.
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Old 09-23-2010, 12:20 PM   #6
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Why would you be wasting your time with kpro? People relocate their IAT's all the time with other motors/cars
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Old 09-23-2010, 02:36 PM   #7
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Okay thanks chaps.
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Old 09-23-2010, 07:59 PM   #8
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Quote:
Originally Posted by spectacle,Sep 23 2010, 02:20 PM
Why would you be wasting your time with kpro? People relocate their IAT's all the time with other motors/cars
KPRO is just not that flexible, you only have a few sensors that can be used b/c there is now way to easily change the calibration. They do have trims that can be tuned but there is serious lack of resolution only (5) cells for low and high load. That is why I am not sold on the KPRO as a whole, there is a lack of user ajustablity however for a simple build it is sure a lot easier.
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Old 09-23-2010, 10:24 PM   #9
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This is called heat soaked, this is why many of us have gone the FMIC route. When using a FMIC, as soon as you start moving the temps drop instantly, the same happens after you hit on it. When you are at WOT it starts dropping but after a point it starts rising and gets around 60. After that it takes more time to drop down to 50 again. This is the main difference with FMIC, since the intercooler is away from the engine, it doesn't gets hot when the engine does, and hence provides the intake manifold always with fresh cool air. The Aftercooler gets heat soaked inside the engine compartment and although the cooling system with the water and the fins inside the AC are running cool water it takes time to actually cool the air since everything in there is hot.

Leave the IAT sensor where it is, relocating it will not cool the air, will just show you a lower reading. Retarding timing above 45 might actually be a good thing since you are not running AEM.
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Old 11-06-2010, 07:20 PM   #10
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While I agree that just relocating the OEM IAT sensor isn't going to do you any good. But changing to a "better" sensor if you have a standalone ECU that you can calibrate for one could definitely be advantageous!

Here's my experience and opinion on this for what its worth. The IAT sensor's tip is a metal probe, which we know from basic thermal dynamics, will induce a small delay into the time it takes the sensor to actually report a change in intake air temp.

Based on the following, I think a better IAT sensor could be used. The high performance SeaDoo's I work with come in a few different performance models with only very slight changes. There is a supercharged model, and a Supercharged Intercooled model. The Supercharged model has an IAT sensor that is the same design that is used in our cars. It has a metal probe tip. However the Supercharged Intercooled model has a different upgraded sensor. I would post pics, but I don't have the proper forum access to do so for some reason... Long story short, the higher end sensor does not have a metal probe, it is a more open design,looks like a diode with a small plastic cage around it to protect the sensor element. I was curious of the differences and why the use of the different IAT sensor in the higher HP rated motor configuration and did some testing of my own on the two sensors. Turns out the difference is the sensor without the metal probe responds to changes in temperature MUCH quicker than the sensor that has the metal probe.

So moving the sensor just changes how you perceive the AIT, a sensor that has a quicker response time to temp changes WOULD be a very worthwhile upgrade!

I'll try and do some research on part numbers, and get some pics of the two sensors for comparison, etc... But being that I already have a temperature calibration table for the Seadoo sensors, I may drill/tap my intake for one of the more responsive SeaDoo sensors..
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