relocating IAT

Justin · Post by **Justin** » Wed Oct 29, 2003 11:59 am

Has anyone done this Mod? Any benefits/disadvantages? Exactly what does it de besides lower the compter reading 20-30 degrees cooler in the computer?

a2b · Post by **a2b** » Wed Oct 29, 2003 1:13 pm

it makes the back seat bigger

Justin · Post by **Justin** » Wed Oct 29, 2003 1:24 pm

yeah on the mods page, it looks like Steve did it and was the only one. probably not worth spending $40 . I can save it and buy beer

a2b · Post by **a2b** » Wed Oct 29, 2003 3:29 pm

Justin wrote:yeah on the mods page, it looks like Steve did it and was the only one. probably not worth spending $40 . I can save it and buy beer

thats alot of beer

adrenalnjunky · Post by **adrenalnjunky** » Wed Oct 29, 2003 7:51 pm

This was a really common mod to do on the Z24's back a few years ago--I dunno why I would cost $40--just pull your IAT sensor out of the air intake hose, splice in a legnth of wire long enough to route it up behind your grille somewhere so that it reads air that is a couple of degrees cooler than that that might be sucked in by the air intake itself.

The most you will get out of it is a little bit of low end.

marks10cc · Post by **marks10cc** » Mon Nov 03, 2003 2:28 pm

Yeah... this is one I did on my Z24... only thing it gave me was a real nice gasoline smell on cold start-ups and a drop of 1-2 MPG's. No performance gain that I could see, which makes me wonder how much gasoline I had pooled in my cat

adrenalnjunky · Post by **adrenalnjunky** » Mon Nov 03, 2003 3:43 pm

I didnt ever do it either -- I was running a RKSport cold air intake down into the bumper/fenderwell, so I was pulling in cool air from the front and under the car -- never figured I needed it.

Steven · Post by **Steven** » Thu Nov 06, 2003 11:51 am

I did the mod with the idea of ... every little bit counts. Not sure if I saw much... would I say its worth it... can't really say... but as you can see from my list of things I did to the S10... every little thing counts.

Check out www.sshotrods.com and look under performance stuff for the 4.3. One of the items is relocating the IAT sensor for a cooler air reading. There it explains it better.

Hope that helps some.
Steven

Post by **HenryJ** » Sat May 01, 2004 7:44 pm

I am dredging up an old topic because I thought i had posted some of this information.

I didn't do the IAT relocation for performance reasons, and really didn't notice any gains.

Some time ago I installed the Jet 180* thermostat. It worked fine with the stock radiator and kept the temperature in a more comfortable range for the summer temps that we can get around here.

Then I upgraded to the larger radiator and the larger supply of coolant in the radiator was just enough to delay the warm up setting the SES light.

After learning that the PCM uses readings from the IAT and ECT to determine the amount of time to reach the preset threshold of 178* , I thought I'd relocate the IAT and see if it bought me enough time to run the 180* stat.
It worked! This was done with the modded stock airbox.

I then went to the FIPK. At first I thought that it would not be an issue since it did not set the light for quite some time (takes 13 failures to set the light), but invariably it did set the light again, so I removed the stat.

Now that I have some time again I decided to remove the filter restriction indicator and install another IAT in it's place. this has been about a week ago since I relocated the IAT and installed the 180* stat.

So far it has been working, and it should have set the light by now (I hope

)

So, if anyone installs the 180* stat and has it setting the SES, you might try relocating the IAT to buy some time

How I made my own extender:
I grabbed an eighteen inch section of the IAT wiring harness with the correct plug that attaches to the sensor, and two used sensors , and the grommet from the salvage yard.
I then carefully cut the sensor end off of one of them and soldered the cut end of the wire harness to them heat shrink insulated them and covered the now male on one end female on the other end harness extender that I now have with some black corrugated loom.

No cut, "plug-n-play" extender

and less than $5 worth of parts

You are all probably thinking..."Does this guy spend all his spare time wandering around salvage yards thinking about what he can build with all the junk?".............I wish!

Post by **HenryJ** » Sun May 22, 2005 3:29 pm

f9k9 wrote:...I threw another SES light today on a trip due to my t-stat so changing it tomorrow will be a 2 min job.

Reed, check out the post above this one for the solution to your cold stat problem. The relocated IAT sensor has been working for me ever since that post over a year ago.

The temperature readings ahead of the MAF sensor are better. By that I mean that if you test the temperature of the incoming air charge, and then read the IAT sensors temperature. The readings are closer with the IAT in front of the MAF sensor.

F9K9 · Post by **F9K9** » Sun May 22, 2005 3:45 pm

Once again, Thanks

F9K9 · Post by **F9K9** » Sat May 28, 2005 1:36 pm

Okay, went to a couple salvage yards today looking for the harness to the IAT and struck out

Killing time while waiting for Sue to wake up (worked last night 7P - 7A) and found this ITEM on Ebay.

If you can ignore the claims to an extra 20 HP increase and a few other things it just might be a work around to the relocation of the IAT.

Looking at all his items on ebay, it appears that he uses a resistor in his plug and play applications.

Do you think a "resistor" could fool the programing into thinking the air is cooler?

I haven't thrown another code ref. my T-stat since I reset it but for $2.99 and $1.99 shipping it may be worth a shot.

I've tucked alot more than 5 one dollar bills into some strangers g string without getting anything out of it in days gone by

Post by **HenryJ** » Sat May 28, 2005 4:08 pm

f9k9 wrote:Okay, went to a couple salvage yards today looking for the harness to the IAT and struck out

Don't give up , there are tons of them out there and most salvage yards don't really care about the wiring.

... found this ITEM on Ebay. ... might be a work around to the relocation of the IAT. ... it appears that he uses a resistor in his plug and play applications.

Do you think a "resistor" could fool the programing into thinking the air is cooler?

Might work, but I don't like it. Mileage will suffer since the PCM will no longer compensated for the incoming air temperature correctly.

...haven't thrown another code ref. my T-stat since I reset it but for $2.99 and $1.99 shipping it may be worth a shot...

Do a search over on ZR2.com for this resistor mod. They run under .25 each and can be picked up at your local radio shack. $5 will get you quite an assortment.
Different resistances will tell the PCM different temperatures. Most use the resistance that shows sub 60 degree temperature so that the PCM richens the mixture.

Relocating the IAT does not disable it, and IMO locates it in a position where it's calibration is closer than the stock position.

You will have to walk a few yards, but the wiring off any S-series or full size with the same IAT sensor will work. I would look at everything from 1996-up.
The air cleaner restriction gauge grommet will work for the IAT sensor, so if you don't want to buy another one, you can grab one of those to plug the other hole.
I am running both with sensors right now. I'll probably punch another hole so that I can install my gauge again, but right now I am creating as many redundant systems as possible.

EDIT:

Gary Westover wrote:Another little trick I picked up at s10.org,
Installing a 4.7K ohm 1/2 watt 5% tolerence resistor in place
of your Air temp sensor, tricks your computer into thinking that
intake air is cooler, about 40C.

What I did was hook up the resistor to one wire, and put a female connector on
the end of the resistor, and a female connector end on the other wire going to
the sensor, then I put a male connector on the wire going to the VCM

I hooked it up in the bypass mode with the resistor in place of the sensor
The other connector is there incase I need to smog the truck, hooking it up
puts the sensor back into the circut and takes the resistor out.

marc_w wrote:I was seeing around 3.7K on the meter, at idle, which tells me I'm at about 70*F in the intake at about 30*F outside air temp. The 4.7K ohm resistor probably dropps the 'as seen' intake temp to like 50-60*F.

I didn't have much luck with this mod in the cold weather, because when the engines cold it actually needs a larger resistor (to simulate a lower temp) to prevent the bog I got. At least that's what I'm guessing here.

F9K9 · Post by **F9K9** » Sun May 29, 2005 5:33 am

Good info, it does make sense.

Didn't think to check full size engine compartments. One of the yard is somewhat new and specializes in the smaller trucks

F9K9 · Post by **F9K9** » Tue Sep 20, 2005 3:32 pm

HenryJ wrote:How I made my own extender:
I grabbed an eighteen inch section of the IAT wiring harness with the correct plug that attaches to the sensor, and two used sensors , and the grommet from the salvage yard.
I then carefully cut the sensor end off of one of them and soldered the cut end of the wire harness to them heat shrink insulated them and covered the now male on one end female on the other end harness extender that I now have with some black corrugated loom.

I returned to a salvage yard today looking for a ZR2 diff and thought I would make a quick look for the IAT sensor and wire. They always "weird out" when I show up with a tie and sport coat and then go into the yard but, I located one and did not have a shopping list with me and only grabbed the harness and one sensor.

Of course, at the "check out lane" I was met with a toothless "what is that?"

Anyway I bought it and did not think to grab a grommet but the thing was in the plastic flex tube and I did not see a grommet. I plan on using a male and female connection (hidden from dealer's view) and locating the IAT in my airaid metal tube. Does anyone know if. I need a grommet, where I could attain one or, if I can just drill and press fit in the new location?

Post by **HenryJ** » Tue Sep 20, 2005 3:37 pm

You need a grommet.

The best one would be the one from a late ninties - early two thousands full size. The one for the filter restriction indicator. It is to the back side of the airbox outlet. In the airbox.

You could also get one at your local autoparts store, or hardware store. The would not be as thick, but probably would work.

F9K9 · Post by **F9K9** » Tue Sep 20, 2005 4:08 pm

HenryJ wrote:You need a grommet..........The best one would be the one from a late ninties - early two thousands full size. The one for the filter restriction indicator. It is to the back side of the airbox outlet. In the airbox.......

So, I guess my stock airbox doesn't have one?

Post by **HenryJ** » Tue Sep 20, 2005 7:15 pm

f9k9 wrote:So, I guess my stock airbox doesn't have one?

Nope.
The IAT goes in the flex tube on the s-series and we don't have a restriction indicator.

F9K9 · Post by **F9K9** » Tue Sep 20, 2005 7:23 pm

Okay, then I will have to wait for another day to locate a full size airbox because the place I went to today was the only place within driving distance during my work week lunch hour and they specialize in mid size PUs.

Everything else is closed on weekends.

Thanks for the help

Post by **HenryJ** » Tue Sep 20, 2005 7:36 pm

Take your IAT sensor to the hardware store and get a grommet that fits snugly. They will work fine. The main thing is to avoid unfiltered air access.

F9K9 · Post by **F9K9** » Wed Sep 21, 2005 2:45 am

HenryJ wrote:Take your IAT sensor to the hardware store and get a grommet that fits snugly. They will work fine. The main thing is to avoid unfiltered air access.

Thanks, will try that today

gocntry · Post by **gocntry** » Wed Sep 21, 2005 3:35 am

HenryJ wrote:The main thing is to avoid unfiltered air access.

DOHH!!

I Have Mine In The Front Of My Swissed Air Box In The Lower Part, Guess I Should Move It Up To The Lid So It's After The Filter.

F9K9 · Post by **F9K9** » Wed Sep 21, 2005 3:45 am

gocntry wrote:
HenryJ wrote:The main thing is to avoid unfiltered air access.

DOHH!! I Have Mine In The Front Of My Swissed Air Box In The Lower Part, Guess I Should Move It Up To The Lid So It's After The Filter.

I think your fine

He meant unfiltered air entering your intake. He was concerned that the air was going to get in around my IAT . Your filter is preventing this.

Post by **HenryJ** » Wed Sep 21, 2005 3:47 am

The sensor itself does not need filtered air, however it is a good idea to have it in the air flow.

Just avaiod the intake having a chance to pull unfiltered air.

gocntry · Post by **gocntry** » Wed Sep 21, 2005 5:28 am

F9K9 wrote:I think your fine He meant unfiltered air entering your intake

HenryJ wrote:The sensor itself does not need filtered air

Ok Cool....I Have My IAT Mounted In The Front Of The Lower Air Box Right Next To Where The Factory Air Intake Pipe Used To Be.

Man I Have To Learn To Read Better I Totally Misunderstood That

F9K9 · Post by **F9K9** » Sun Nov 13, 2005 4:17 pm

Okay, went on a road trip this weekend. It was north about 2 1/2 hours to IN to visit the MOTHER-IN-LAW

I threw the low coolant temp code twice before I bought a 195° T-stat, a POS socket set at their local BIG LOTS (Didn't carry my tools for an interstate trip due to the blonde american version or the former first lady of the Phillippines and didn't have the room) and swapped out my JET 180° t-stat.

My IAT was relocated before the MAF on the metal tybe of my Airaid. Ideas?

Post by **HenryJ** » Sun Nov 13, 2005 4:38 pm

Next time just clear the code and finish your trip. It takes more than once to trigger the code. Make sure that the code tripped is the low coolant temperature. Don't ass-u-me

Well it looks like plan B doesn't work for you. I don't know what for you to try. Relocating the IAT here worked for mine-

I have reversed this and gone back to the stock location several times. It sets the MIL everytime within a week.

The whole idea here was to find cooler air and buy some time to reach the threshold. The 2001 PCM is tight, but maybe yours is tighter? Maybe you need to find cooler air? How about moving the sensor further from the MAFS? Mine is as close to the air cleaner as I can go.

I really can't think of any other mods that I have made that would help the situation other than perhaps the electric fans? They may be helping the engine to warm up quicker.

I guess plan D will be to install the electric fans and try the 180 stat again

F9K9 · Post by **F9K9** » Sun Nov 13, 2005 5:14 pm

HenryJ wrote:Next time just clear the code and finish your trip. It takes more than once to trigger the code. Make sure that the code tripped is the low coolant temperature. Don't ass-u-me

Did you think I was gonna assume that again

I can not recall off hand the exact code but, I had the book in hand when I read the code and double checked. It was low coolant temp and I believe it ended in "128"

I threw the second light in under a day and it was definitely under 5 cycles. I threw the t-stat in this morning, in the motel parking lot, and I know I had I had over five cycles after I replaced it (one was shoe shopping

). No light!

I thought I remembered that it took something like 15 or 51 cycles to throw the light again and was shocked when I threw it in under 24 hours.

BTW, I picked up a Stant this time and they come with a new gasket. Something, I cannot say for JET at 4X the price

Post by **HenryJ** » Sun Nov 13, 2005 5:26 pm

How far forward of the MAFS did you relocate the IAT sensor?

The reason for the stock temperature stat being cheaper is partially due to the quantity. The 180* stats are not used in production vehicles, therefore they are specially built in smaller quantities.

I wish there were lots to choose from, but there just are not any choices like a thermostat without the bypass valve.

F9K9 · Post by **F9K9** » Sun Nov 13, 2005 5:39 pm

HenryJ wrote:How far forward of the MAFS did you relocate the IAT sensor?

I was thinking along that line. I wasn't pleased where I had to place it due length of wire I had. I placed it just before the bend of the Airaid metal tube,

Post by **HenryJ** » Sun Nov 13, 2005 6:50 pm

I'd sure try running close to the filter. It might be enough to buy the time you need.

killian96ss · Post by **killian96ss** » Sun Dec 18, 2005 7:09 am

Has anyone with this mod ever checked the temperature difference from the stock location to their new location near the filter? It is very easy to do with a scan tool. I can't imagine the change is more than a few degrees since the distance has only been changed by a foot or less. The companies that sell the harnesses for this mod claim a temperature difference of 20*. I'm just curious what the real life #'s are.

Steve

Post by **HenryJ** » Sun Dec 18, 2005 7:17 am

I'll see how this afternoon goes. If there is time I'll check it out with Autotap.

That foot makes a huge difference just in location though. The IAT sensor is now on the cool side of the heat shield (or airbox) and located in such a position that the engine heat does not get so readily absorbed.

The actual temperature difference may be small, but obviously in my case it is just enough. I set the MIL within a few days after switching back to the stock location.

killian96ss · Post by **killian96ss** » Sun Dec 18, 2005 7:34 am

HenryJ wrote:The actual temperature difference may be small, but obviously in my case it is just enough. I set the MIL within a few days after switching back to the stock location.

My guess would be 5* colder and maybe as much as 10*, but I just don't believe some companies claims of 20-30* by only moving the IAT sensor a foot. When you switched back to the stock location and set the SES light again, was the outside temperature a factor, or are you just running on the edge due to the bigger radiator, or maybe the temp and cooling capacity were both a factor. I have never set the SES light because of my 180* t-stat, but I also don't live where the temps go under 30* very often.

Steve

Post by **HenryJ** » Sun Dec 18, 2005 7:46 am

The colder weather really should not play a big part in it unless the formula is flawed.
I am sure the bigger radiator is the key here, since I was able to run the 180 stat MIL free before its installation.

It is just right on the edge. I think the 5 degree guess is a good one. That would be my estimate. I'll try to check it after a shopping run to Boise

Post by **HenryJ** » Sun Dec 18, 2005 2:16 pm

Made it back and checked with Autotap. Twenty degrees difference.
The forward IAT sensor , near the filter reads 43 degrees, the one behind the MAF sensor in the stock location reads 63 degrees.

I wouldn't have guessed that large of a difference, but that is what they read.
Outside temp today is 19 degrees and we just returned from a trip to Boise, so the engine was warmed up to operating temperature.

I do have a refletix insulated heat shield, that may help some.

killian96ss · Post by **killian96ss** » Sun Dec 18, 2005 8:45 pm

I never would have believed it!

Thanks for checking the temps!

Steve

killian96ss · Post by **killian96ss** » Mon Dec 19, 2005 9:33 am

I wonder what this mod will do to the emissions?

20* is a big difference and will affect fuel and timing tables. It seems like this mod would make a few hp due to the engine reading a 20* cooler intake charge. It would be interesting to see what happens with the fuel trims when switching from the stock location to forward of the MAF. Is there a reason why GM engineers always have the IAT placed after the MAF? I believe all GM cars with an IAT sensor have them placed after the MAF. Maybe there is a reason for the placement, but it is also possible that this is something GM overlooked since it is not a problem and engines with this setup are running fine. This mod still seems like a good idea to me.

Does anyone know if JET harness Part # 61620 comes with a new grommet and a plug for the old hole? I know this is the lazy & expensive route, but I am just curious.

Steve

gocntry · Post by **gocntry** » Mon Dec 19, 2005 10:23 am

I Was Lazy And Ordered A IAT Harness From Jeg's Too. The Part # Is 61620 And It's A Jet. It Came With The Extension Harness, A New Grommet And An IAT Sensor. I Left The Factory One Where It's At And Just Mounted The New One In The Air Box. When I Take The Crew In For A State Inspection Or Emissions Inspection I Unplug The Extension Harness And Re-Plug Into The Factory IAT. So No Questions Are Asked About The Unplugged Sensor If They Happen To Look Under The Hood.

killian96ss · Post by **killian96ss** » Mon Dec 19, 2005 10:49 am

gocntry wrote:I Left The Factory One Where It's At And Just Mounted The New One In The Air Box. When I Take The Crew In For A State Inspection Or Emissions Inspection I Unplug The Extension Harness And Re-Plug Into The Factory IAT.

Good idea.

I think I will probably do the same.

When I first saw the $40 price for the JET harness, I was like damn that's a lot of $ for a simple wiring harness,

but if it comes with a new sensor, then that definitely makes the price more worth it.

Steve

F9K9 · Post by **F9K9** » Mon Dec 19, 2005 2:40 pm

killian96ss wrote:
gocntry wrote:I Left The Factory One Where It's At And Just Mounted The New One In The Air Box. When I Take The Crew In For A State Inspection Or Emissions Inspection I Unplug The Extension Harness And Re-Plug Into The Factory IAT.
Good idea. I think I will probably do the same. When I first saw the $40 price for the JET harness, I was like damn that's a lot of $ for a simple wiring harness, but if it comes with a new sensor, then that definitely makes the price more worth it.

Steve

I picked up extra wiring and a sensor at a local salvage yard for $5 (if I recall correctly).

F9K9 · Post by **F9K9** » Sun Jan 07, 2007 9:12 am

Well, I have given it enough time now and I haven't a thrown low coolant temp code this winter with the Jet 180° T-Stat. I moved the IAT to just behind the air filter. It certainly did the trick

LonestarZ · Post by **LonestarZ** » Sun Jan 07, 2007 11:54 am

Crap.. wish I would have known about this earlier.

I just bought a extra capacity radiator and I was planning on when I replaced my radiator to also replace my Tstat with a Stant 180* that I have had in a box doing nothing for a while.

Basically from what I am reading is that if I do the actions above I am going to throw a SES unless I move the IAT. That bites.

Post by **HenryJ** » Sun Jan 07, 2007 12:09 pm

Just another $5

Does that Stant thermostat have a bypass valve?

F9K9 · Post by **F9K9** » Sun Jan 07, 2007 12:53 pm

LonestarZ wrote:..........I just bought a extra capacity radiator...............

Off topic I know but, if, you have an auto tranny adding a tranny cooler would be very easy to do when you add the extra capacity radiator. I combined the two mods and replaced the hoses at the same time. Made everything easier to do when installed together. Then changing from Dexcool could be done at the same time because you have to drain the coolant anyway.

Just a thought.

LonestarZ · Post by **LonestarZ** » Sun Jan 07, 2007 6:50 pm

f9k9 wrote:
LonestarZ wrote:..........I just bought a extra capacity radiator...............
Off topic I know but, if, you have an auto tranny adding a tranny cooler would be very easy to do when you add the extra capacity radiator.
Just a thought.

Umm.. What does my Sig Say?

HenryJ wrote:Just another $5

Does that Stant thermostat have a bypass valve?

Yeah.. like I know how to do anything electrical..

F9K9 · Post by **F9K9** » Sun Jan 07, 2007 8:38 pm

LonestarZ wrote:
f9k9 wrote:
LonestarZ wrote:..........I just bought a extra capacity radiator...............
Off topic I know but, if, you have an auto tranny adding a tranny cooler would be very easy to do when you add the extra capacity radiator.
Just a thought.
Umm.. What does my Sig Say? .....

Didn't notice the Sig. Add an oil cooler then

daevans315 · Post by **daevans315** » Tue Jan 09, 2007 11:38 am

I started popping the code this winter even after the PCM reflash for the 180 thermostat. I found the IAT relocator here. http://autotruckpart.com for $33.

Beware.. !!!FREE SHIPPING!!! is advertised, however there is $5 Handling

. Still cheeper than Jegs.

daevans315 · Post by **daevans315** » Thu Jan 11, 2007 10:44 am

Never mind on the above company. Today I got this email today.

Hello, unfortunately we have cancelled your order. This item is on backorder for an extended period of time. No Charge has occurred.

I'm guessing their price was a little to cheep.