how to tap hole for GM IAT sensor?

[the poi]

dunno quite which forum to slap this in...but im going to MS in a couple of weeks (perhaps) and I want to know what i can do about placement of the IAT sensor. Is the intake mani the best place?How exactly do I get a threaded hole in it... and will the fact that its aluminum and the sensor's steel cause any major problems (differnt thermal expansion)?

[poulson01]

Don't use that sensor. The one you want fits into the intake boot. It's plastic and has an open NTC resistor in a little cage at the end. The brass one takes too long to react on a turbo car. I have the dam thing right in my hand but there is no P/N on it.
Ahah! Under the connector.
#12160244

[Anonymous]

I'm using the solid sensor as my IAT sensor, and yeah it takes a bit longer to react but it's not the end of the world until I find an open-element one. It does move fairly quickly...

I drilled a hole in my intake manifold, right in the middle of that raised boss shaped like a cold start injector mount. I started with a 1/2" drill (that's my biggest size) and opened it up with my die grinder (use aluminum cutting bits!) until it was close to the root diameter of the sensor's threads. Then I cut a slot into the first three threads of another fitting with the same thread (I used a heater hose pipe from an old cylinder head) and turned that into the hole, cutting threads as it went. I found that turning it with a wrench pulled it over too much and the threads wouldn't start, so I used my impact wrench. (You could use a deep socket and a long extension, bracing the extension with one hand while turning the socket with the other - this should keep the sensor perpendicular to the head.) The threads turned out a bit ugly, but the sensor went in and tightened right up. It hasn't been tossed out yet, but I might go get some plumbing dope and seal it in there. The sensor is externally grounded, so compromising the electrical continuity between sensor and manifold shouldn't be critical.

The one that Mike suggested isn't the one to use, though. That one is for a normally aspirated engine, even though it's got the open element for fast response. That one fits into a plastic boot, but it's only a press fit and it could shoot out if you don't clamp it in there. Keep your eye out for Pontiac Grand Am Turbos, late '80s to early '90s, in the junkyard. They have a threaded sensor in the intake manifold, and it's the proper open-element one.

[Hank Scorpio]

I put mine here, and while it works, the intake is fairly thin in that spot so be careful.

Also, iirc its like a 3/4" pipe thread fitting.

http://www.pbase.com/image/16028937.jpg

[Anonymous]

The boss I'm talking about is the one seen just above the fuel rail, just to the left of the 1/4" vacuum line, in the picture above. Much thicker there...

[Hank Scorpio]

The boss I'm talking about is the one seen just above the fuel rail, just to the left of the 1/4" vacuum line, in the picture above. Much thicker there...

We thought about that, but I wasn't sure if it would be wide enough.

That is the prefered spot though.

[Anonymous]

It is wide enough, barely.

[linuxman51]

i stuck mine where the cold start injector would normally go, seems to work rather well 8-)

[945ti]

You could put it in the IC pipe like a B230ET, it has it stock measuring right out of the IC wiht the cage and element type sensor. This is how every SAAB I have seen does it too. :e-shrug:

[poulson01]

[quote:558f84deb1]You could put it in the IC pipe like a B230ET, it has it stock measuring right out of the IC wiht the cage and element type sensor. This is how every SAAB I have seen does it too.[/quote:558f84deb1] :werd:

[the poi]

what'd you guys use to tap the threads in the CSI hole? Am i gonna need to change the intake manifold gasket after I take it off?

[linuxman51]

well, it wasnt exactly scientific, basically, my accomplice in crime drilled a hole and made it fit. drill it out and tap it, that should work well.

[Anonymous]

I used an old 3/8 NPT pipe fitting and I cut a couple of slots across the threads with a hacksaw. Then I turned this into the hole in the manifold - it cut the threads just fine...

However, I'm now finding that putting the IAT sensor in the intake manifold isn't a great idea. I'm picking up lots of heat soak when I shut it off and it runs REALLY LEAN for the first few minutes after I start it again. Acutally, it'll run lean until I hit boost and blow enough fresh air onto the sensor. I'm now using an open element sensor from a second gen Quad4, but it's not turning the trick.

So now I'm going to use a fitting welded into the IC-to-TB pipe and take the temp there. That way all the air going into the engine passes by the sensor, plus it won't heat soak as badly. I think that's the source of all my inconsistencies with Megasquirt. The Quad4 I took it from puts the inake right near the throttle body, where all the air entering runners #2 thru 4 has to pass by it. In the B23/230 EFI manifold, the sensor sits out of the direct air stream, so unless the engine's flowing enough air that it gets a good reading, the sensor is influenced by the heat in the aluminum manifold.

[TurboBrick940]

well, it wasnt exactly scientific, basically, my accomplice in crime drilled a hole and made it fit. drill it out and tap it, that should work well.

Everything Kenny does to a car is a crime. :whip:

I would go to a truck supply / heavy equipment store. Take your sensor, they should have a ring that will match up to it, that's what we did for Robin's. Hacked it to the proper length and now he just needs to get it welded on. That way its removable and not screwed into thin pipe/manifold/ice.

[the poi]

Hmmm, that seems to be a good point matt... I guess ill be getting a some experience in aluminum welding a little bit before i thoguht i would. A small pipe, a flat piece of wluminum with a hoel in it....seems like it ought to work best in the IC pipe

[Anonymous]

Or you could use 2.25" exhaust pipe for an IC pipe, like I did... Then a Home Deopt sourced 3/8" NPT forged steel coupling or bushing can be used, chopped down to proper length, and welded on by just about anybody. Makes it easier to weld on nipples for BOV/CBVs, post-intercooler wastegate feeds, IAC valve nipples... that kind of thing, when you're not set up to weld aluminum. It's not like the steel pipe is gonna weigh that much more than the aluminum - a few ounces, maybe.

[the poi]

Or you could use 2.25" exhaust pipe for an IC pipe, like I did... Then a Home Deopt sourced 3/8" NPT forged steel coupling or bushing can be used, chopped down to proper length, and welded on by just about anybody. Makes it easier to weld on nipples for BOV/CBVs, post-intercooler wastegate feeds, IAC valve nipples... that kind of thing, when you're not set up to weld aluminum. It's not like the steel pipe is gonna weigh that much more than the aluminum - a few ounces, maybe.hmmm, did you use any bends at all or did you just run a straight pipe from IC to the throttle body bend?

[Anonymous]

You need about a 20-30 degree bend right at the intercooler, and then it's pretty much straight back to the rubber elbow at the TB. I used a truck radiator hose for my elbow, as I couldn't find a B230FT elbow to use. When building the IC-TB pipe for Dale's car, we used 3" exhaust pipe and the elbows' radius was too great to just do a simple "J" shape, so we had to do a bit of a snakey-snake, sort of like the original but exaggerated.

I just welded in the coupling last week, and after driving the car somewhat I'll say that it's much better, but I think my warm idle problems are as much a result of the huge injectors and my desire to run lean when I can, though the heat soak is still a problem. I have a couple more tricks up my sleeve, so I think I'll get 'er figured out...

Doug - are you having restart problems too, or do you drive your car enough to know?

[MikeHardy]

this is the one from a B230ET
http://www.pbase.com/image/19571558/large.jpg

and heres where it goes
http://www.pbase.com/image/21400013/large.jpg

[Anonymous]

Oh, that is SO what I wanted to see... Perfect! I figured it was way more consistent up there but I didn't want to run the wires. I'll do that mod tonight and see if it helps. It may be my junkyard sensor, too, but whatever it is I'm getting fairly frustrated by it. That and this friggin' wet September 16, first-snow-of-the-year-and-we're-supposed-to-get-10-to-12"-of-the-stuff-and-I-have-no-heater-core-to-beat-it-back-with!!! Grrr!

[coldfusion21]

not to bump an almost 2 year old thread but i thought i would add my two cents in to the mix.

i found the open element sensor in the junkyard with a metal ring that was pressed into the airbox of the donor car. so all i had to do was screw out the sensor and then yank the ring out, and jb weld the ring into a hole i cut into the IC pipes.

i also happened to use the idle hole for this, by grinding around the weld at the base of the nipple and smacking it with a hammer a few times, out pops the nipple and the hole is almost the perfect size.

[Boris740]

I bought a two dollar high speed thermistor from Digikey and soldered it to a BNC connector. The BNC was installed in the exit end of NPR intercooler. The thermistor part number is KC005G-ND. It is a size of a small diode and has survived in my car for over a year.

The three resistance points are
°F R (Ohms)
-22 65,429
77 2,786
149 545

Here is how it looks
http://www.viatrack.ca/Intercooler/THERMOUNT.JPG
http://www.viatrack.ca/Intercooler/THERMCON.jpg
http://www.viatrack.ca/Intercooler/THERMBNCS.jpg

[blkaplan]

i did this.

http://www.pbase.com/blkaplan/image/37429460.jpg

i got an extra one 50 bucks takes it

[sick78_242GT]

is that the best way to run it because im about to mega squirt and i was wondering the same thing that seems to be the best place to put it but i want to but it on the bottom of the ic pipe so it looks alot cleaner...what is that senser called i don't understand where to get one and what kind of car its for...if you can help that would be great thanks

chris

[blkaplan]

its called an IAT Intake air temperature sensor you can get em online or at any auto parts store just get that works on any gm model that looks like the ones in the pics from the megasquirt site, if you search im sure you can find a part number online

[blarf]

is that the best way to run it because im about to mega squirt and i was wondering the same thing that seems to be the best place to put it but i want to but it on the bottom of the ic pipe so it looks alot cleaner...what is that senser called i don't understand where to get one and what kind of car its for...if you can help that would be great thanks

What about grabbing the sensor and housing from a Regina car and just placing the thing in place of the AMM? or in between the IC and the intake ducting?

--
alex

[sick78_242GT]

ok

[sick78_242GT]

do i put that senser before or after the inter cooler?

[blkaplan]

after

[745 TurboGreasel]

FYI the GM guys usualy relocte the stock sensor from the intake manifold even on NA cars. heat and vibration from the manifold prevents proper function. relocation kits for TPI cars are readily available on ebay and have about a foot of wire.

[blkaplan]

here is a pic of the intercooler mounted style IAT

http://www.pbase.com/blkaplan/image/40213962.jpg

i dont think you want to mount it on the bottom for the same reason you dont want to mount a 02 on the bottom, you dont want any condensation to sit on there

[Boris740]

do i put that senser before or after the inter cooler?

After. Megasquirt needs to know the temperature of the air going into the engine.

[sick78_242GT]

cool thanks alot (i wonder when im going to get ms? how long does it usually take from kenny)

[TerribleOne]

I just drilled a hole in the intercooler pipe going to the T/B and screwed the sucker in with a big wrench, I didn't even bother to tap it or anything. and it doesn't leak.

The IAT sensor can be seen at the top of the pic underneath the aluminum IC pipe. (http://www.pbase.com/terribleone/image/25498178)

[swedefiend]

I just drilled a hole in the intercooler pipe going to the T/B and screwed the sucker in with a big wrench, I didn't even bother to tap it or anything. and it doesn't leak.

The IAT sensor can be seen at the top of the pic underneath the aluminum IC pipe. (http://www.pbase.com/terribleone/image/25498178)

Yeah, we did the same thing to Ben's car. We did tap his, but it only left one thread in the pipe. I can see how the sensor might tap itself. I would just go slowly and use a little lube.

[745 TurboGreasel]

I would just go slowly and use a little lube.

Yeah, that is what they all say.

[blkaplan]

how many threads do you guys have ingaged? the pipe looked way to thin on mine to attach without a proper weld bung,

i would be worried of blowing that out under boost, or having trace leaks at high boost levels

[242Fast]

there's this..."hole" in the throttle body right next to the two vacuum lines on the top side. i drilled it out with the biggest bit i had and used an abrasive to finish it off. the correct drill bit size for a 3/8 npt tap was 37/64, 20$ at ACE, i chose the abbrasive.
http://home.comcast.net/~bigleonard/IM001094.JPG http://home.comcast.net/~bigleonard/IM001095.JPG

[Geoff240Ti]

there's this..."hole" in the throttle body right next to the two vacuum lines on the top side. i drilled it out with the biggest bit i had and used an abrasive to finish it off. the correct drill bit size for a 3/8 npt tap was 37/64, 20$ at ACE, i chose the abbrasive.
http://home.comcast.net/~bigleonard/IM001094.JPG http://home.comcast.net/~bigleonard/IM001095.JPG

Wow I really like the idea of putting it there! I think I may just go that route...

[coldfusion21]

Wow I really like the idea of putting it there! I think I may just go that route...
same problem as the manifold would think heat soak would become a problem

[Boris740]

same problem as the manifold would think heat soak would become a problem

YES. I put mine just behind the throttle plate and the heats soak was defiantly a problem.

[242Fast]

how do you guys tell heat soak from just having hot intake since the turbo intake is naturally right next to the exhaust. just wondering, i haven't had the car on the road too much yet so i'm still learning.

[The Aspirator]

Yeah I usually just dremel a hole in the intake pipe and screw it in, then use JBweld around it to keep it in there. Ghetto, but works fine. Boris I LOVE your idea!! I might just have to try that.

i dont think you want to mount it on the bottom for the same reason you dont want to mount a 02 on the bottom, you dont want any condensation to sit on thereI was talking to Ben (Grebnut) and he said that he used to have his open element IAT mounted on the bottom of his IC pipe and the condensation would actually short it out and make his car screw up. Bad juju.

[coldfusion21]

heat soak is when the surrounding area heats up (like the manifold) and even when the air is colder, the sensor still reads hot because the entire sensor heats up.

[242Fast]

so for those of us who don't have equipment to weld an aluminum bung on a pipe and who don't like to use jbweld on a pipe that'll be pushin 2atmospheres of pressure...would tapping a whole right into the intercooler tank be a good idea(right on the outlet)?

[blkaplan]

so for those of us who don't have equipment to weld an aluminum bung on a pipe and who don't like to use jbweld on a pipe that'll be pushin 2atmospheres of pressure...would tapping a whole right into the intercooler tank be a good idea(right on the outlet)?


if you dont have the right equipment and dont want to ghetto rig it i would recommend you buy the part from me,,,, :-P

on a different note i would not put it in the intercooler tank because on volvo's its plastic and if its metal you would still have heat soak from the radiator there,

as well as the fact that as the air exits the intercooler its going to be @ a different temperature then when it its in the ends tanks....

[Boris740]

how do you guys tell heat soak from just having hot intake since the turbo intake is naturally right next to the exhaust. just wondering, i haven't had the car on the road too much yet so i'm still learning.
Drive the car until it is well warmed up. Stop and wait for ten minutes or so. If you are having trouble restarting it is heat soaked. The IAT thermistor will be warmer than the air resulting in lean mixture.

[swedefiend]

Drive the car until it is well warmed up. Stop and wait for ten minutes or so. If you are having trouble restarting it is heat soaked. The IAT thermistor will be warmer than the air resulting in lean mixture.

hrm... I guess that means I am not having heat soak after all. I still want to move it. If I could just find and aluminum 3/8 bung, I would have it welded to the intake pipe.