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  1. #1
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    The Ultimate in IAT Sensor Relocation

    Lets start right off by saying that this is something I think we all would have jumped on and tried back in 2005 when we had nothing in the way of tuning and aftermarket parts, but now, when its practically 2009, we live in a different world. While this mod undeniably works with respect to completely fooling the IAT sensor, you have to ask yourself how smart it is to do this, and once that question is asked, it begs the next: how smart it is to relocate the IAT *at all*?

    With that said, it may be workable for some purposes. If nothing else it is an interesting experiment and may serve as a platform for something else down the road. Regardless, here is how you completely fool the IAT to read ambient using few if any extra components.

    ---

    We start out by removing the IAT sensor. The sensor is going to be relocated to a place where you want it to receive some protection from the elements, rocks, bugs etc. You have to balance that with the need to give it airflow that is as unrestricted as possible. I had some 1/2" 1-ply silicone tubing in the garage, and I sawed a bit off with a hacksaw in about 10 seconds.



    Stick the 1/2" tubing onto the end of the sensor. 1/2" is, as you can see, a perfect and very snug fit.



    You need only to make the snippet of tubing long enough to protect the sensor, while making it not so long as to unduly insulate it from free-flowing air.



    I have an extra-long IAT connection thanks to my AirHammer, which has an IAT relocation kit. The AirHammer product is quite fancy, having male and female plugs on both ends so you don't have to cut anything, but you can make one yourself by simply snipping the two wires (in the middle!) to the sensor, splicing in your desired extra length and finding a suitable cover for the added length of wire.

    Note I used duct tape to provide some additional stabilization and weatherizing to the wire-ends and connection. With a project like this, you just have to have duct tape in there somewhere.



    With my extension and sensor ready, I snaked the cable thru to the front of the car by going thru the top of the upper radiator baffle on the passenger side. I already have some of that baffle snipped away thanks to the Frankencooler that is mounted up top already, so for me it was just a matter of running the cable. Also if you are wondering what that bare metal box is, its an HID ballast.



    Looking straight down thru the fascia with the hood up, we can see the cable, which I secured to the Frankencooler for stability with... a zip tie. Just as we must have duct tape, a project of this nature requires zip ties to be used somewhere.



    And here is the relocated IAT sensor in its final position. Its *almost* but not quite in direct airflow, and protected behind wire mesh and a silicone buffer. Keeping it near but out of truly direct airflow gives it the final layer of protection against rain, sleet and sparrows.



    Results? Drive the car in slow streets or fast freeways and this is what you see.



    Stop the car at a light or park it and let it idle, and this is what you see.



    Pretty straightforward test results. Its not TOTALLY ambient though. I saw variances as much as 4 degrees above ambient when parked. That could have been the sun breaking out of the clouds, though. Remember the ambient air sensor is under the car and completely away from the sun.

    This test was obviously something I whipped up on a slow afternoon. I'm sure I could have come up with a better relocation location if I wanted to make a longer extension wire. And I imagine I could do better than snipping off some hose for a sensor protector. But this was just something I was playing around with.

    And the begged, $64 question: How smart is it to relocate the air sensor AT ALL, given that in the world we live in today, we now know the PCM uses both the AAT and IAT to decide what it does? Is it smart to have the mods we have, where we are pushing all sorts of limits, and have something that lies to the motor's brain? Especially since many of us have paid some pretty decent money to have a guy reprogram that brain so it is a top performer?

    My gut instinct based on hanging around here and playing with these cars for a few years is that we don't want to be lying to the motor so much as we once did. However, I could be wrong. Feel free to tell me so :-)
    Last edited by MattRobertson; 12-26-2008 at 04:55 PM.
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  2. #2
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    the only thing that matters is.... what difference does it do on the dyno.
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  3. #3
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    Why don't you just have your tune zero the IAT temp spark adjustments, leave the Ambient tables alone, and fiddle with the IAT enrichment tables until you are happy?

    The Ambient sensor has some other logic as part of it that prevents the sensor from showing "heat soak" from a hot radiator and sitting in traffic, but the IAT sensor does NOT...
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  4. #4
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    Well you beat me to it Matt...... we have developed a kit similar to this and will be releasing data, photos and pricing on Jan. 01.

    Our kit features a small,
    1/2 inch breather filter and an extended factory harness with approx. 3 feet of lead, which will be plug and play for those not wishing to cut into your original IAT harness, pricing will be $40.00.

    We will also have available a selection of plugs to neatly fill the existing IAT hole in the intake available depending on the size, we have found 3 possible sizes depending on the manufacturer of the intake.

    Given that this is, a DIY possible modification, I am also going to do a highly detailed step by step for those with nothing better to do in January.

    I would like to give credit to CoolVanilla, who in a post early in December pondered the idea of relocating the IAT completely out of the intake body, this got me thinking...Thanks Jason.
    Last edited by wheelife; 12-26-2008 at 06:18 PM.

  5. #5
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    Its worth noting that I first saw this idea a few years ago. Its never been written up on an LX (A member here did it some time ago just for giggles) but I saw a kit on sale for doing this on a hemi truck. IIRC it was an IAT extension, a plug and a plastic tube, open on both ends with external mounting points and an internal mount that held the IAT sensor in place.

    Lafrad, don't get all technical with me. Remember... duct tape and zip ties. Go further than that and my head starts hurting. My guess is if [email protected] finds out I am lying to his motor like that he will jump onto his sleigh, come down the chimney and kick my ass.

    So I am running with the IAT in the elbow like a good boy :-)

  6. #6
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    Quote Originally Posted by MattRobertson View Post
    Its worth noting that I first saw this idea a few years ago. Its never been written up on an LX (A member here did it some time ago just for giggles) but I saw a kit on sale for doing this on a hemi truck. IIRC it was an IAT extension, a plug and a plastic tube, open on both ends with external mounting points and an internal mount that held the IAT sensor in place.

    Lafrad, don't get all technical with me. Remember... duct tape and zip ties. Go further than that and my head starts hurting. My guess is if [email protected] finds out I am lying to his motor like that he will jump onto his sleigh, come down the chimney and kick my ass.

    So I am running with the IAT in the elbow like a good boy :-)
    Hhe would probably not even call before showing up too :-P

  7. #7
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    Quote Originally Posted by Kamakazie2 View Post
    the only thing that matters is.... what difference does it do on the dyno.
    Well, if your motor needs the info that you are deliberately keeping from it to avoid blowing up, that would be one thing the dyno isn't going to tell you. I'm not smart enough to know under what combination of mods and circumstances such a fear could be realized, but I bet that the LX brain trust can come to a consensus without my inexpert help :D.

  8. #8
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    The max IAT adjustment in spark is LESS than the Max adjustment from the knock sensors.

    Worst this mod could... reasonably... do... is cause excessive knock retard and crappy timing at the track

  9. #9
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    I am confused here...
    Why would I want to lie to the IAT. ISn't it doing some adjustment on timing on what the temp of the air is at the TB.
    If you relocate it then the PCM is adjusting for untrue temps?????
    Now granted some of the timing adjusted may be good btu how much is too much. If the IAT sees 54 degrees biut the true IAT is 110 at the TB then what happens???
    Seems like an accident waitng to happen.
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  10. #10
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    JonzMgnm is offline Just a squirrel, trying to get a nut....

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    Quote Originally Posted by netnathan View Post
    I am confused here...
    Why would I want to lie to the IAT. ISn't it doing some adjustment on timing on what the temp of the air is at the TB.
    If you relocate it then the PCM is adjusting for untrue temps?????
    Now granted some of the timing adjusted may be good btu how much is too much. If the IAT sees 54 degrees biut the true IAT is 110 at the TB then what happens???
    Seems like an accident waitng to happen.
    Although an extreme example would be FUBARed pistons due to detonation, one would hope the Knock Sensors would step in and tame things down. Matt, I love the AAT/IAT temps on the DashHawk when they are close, but you can have them look like that and have an IAT mounted in the intake tract.

    GSM CAI + AFE II = All the ambient air my motor wants!
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  11. #11
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    Quote Originally Posted by netnathan View Post
    I am confused here...
    Why would I want to lie to the IAT. ISn't it doing some adjustment on timing on what the temp of the air is at the TB.
    If you relocate it then the PCM is adjusting for untrue temps?????
    Now granted some of the timing adjusted may be good btu how much is too much. If the IAT sees 54 degrees biut the true IAT is 110 at the TB then what happens???
    Seems like an accident waitng to happen.
    Think of it as the other way around, why do we want the IAT lying to the computer.

    Our testing has shown a considerable amount of radiant heat affecting the sensor due to it's close proximity to the engine block and radiator, when hot.

    By relocating the sensor to an area less affected by this radiant heat we hope to achieve a more accurate reflection of the true air temperature entering the engine.

  12. #12
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    hmmm..........interesting.......very interesting........I look forward to hearing more about this and the kit Lance is releasing


  13. #13
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    Quote Originally Posted by JonzMgnm View Post
    GSM CAI + AFE II = All the ambient air my motor wants!
    Or a Frankentake IV

    Am I reading that right? You have two intakes (gsm PLUS afe)?

  14. #14
    JonzMgnm's Avatar
    JonzMgnm is offline Just a squirrel, trying to get a nut....

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    Quote Originally Posted by MattRobertson View Post
    Or a Frankentake IV

    Am I reading that right? You have two intakes (gsm PLUS afe)?
    Yes, Matt.....with some good-ole-boy engineering the join them together.

  15. #15
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    im confused because everyone says that how GSM locates the IAT sensor closer to the filter near the bumper is bad because it doesnt reflect the accurate temp going into the intake manifold.

    so how is it good to take the true outside temp to send to the PCM when it isnt what is really being consumed by the engine?

    wouldnt this lead to advanced timing, and if the air is too hot by the time its consumed, cause knock?

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