Best way to add secind IAT sensor

[Jake_rorx7]

Hi all, I'm working on an Arduino project and I would like to get an intake air temperature reading into the microcontroller. Two possibilities:

1. I add a new IAT sensor somewhere after the intercooler, or
2. I tap into the existing sensor lines

What is the best way of adding a sensor into the air stream? Is there any unused ports under the manifold I can conveniently add to? Perhaps I can use the bunged 1" port on the back of the elbow somehow? Don't really want to be drilling and tapping holes on the manifold.

Will the signal between ECU and sensor be affected if I tap into it for a voltage reading? Is it even a proper voltage reading or a resistance measurement? Does anyone have any experience with doing something like this?

Cheers

 

[JoeLanger]

You can't tap the wiring on the sensor it won't read correctly. This would in theory work if it was a 0-5v signal but still wouldn't be recommended.

You could set an output from the link as AIT? Not sure actually if it has analog outputs. Or Canbus.

What are you attempting to do?

 

[marco]

You 'can' approximate an analogue output with a pull to ground pwm output from an ecuand a couple of resistors. But, probably easier to just fit a second air sensor- can you still get the silicone hoses with a sensor hole in them, pretty sure they used to be a thing

 

[Jake_rorx7]

You can't tap the wiring on the sensor it won't read correctly. This would in theory work if it was a 0-5v signal but still wouldn't be recommended.

You could set an output from the link as AIT? Not sure actually if it has analog outputs. Or Canbus.

What are you attempting to do?

Thanks for confirming my suspicions it will alter the signal.
I dont have a Link ECU just a little apexi
I'm making an arduino powered info display to replace the boost gauge on the steering column. I have a vac hose going to that area already so I can stick a MAP sensor on that and place it under the dash. Other sensors I'm adding include the IAT sensor (I can see the IAT reading on the apexi handheld, but lets be honest the stock sensor location is kind of whack for heat soak and slow in response so best to add another better sensor to read from), a battery voltage sensor, and an ambient temperature sensor. Once thats all working, I can use the arduino as a controller for an intercooler water sprayer. But thats a showcase for another post when its completed.

You 'can' approximate an analogue output with a pull to ground pwm output from an ecuand a couple of resistors. But, probably easier to just fit a second air sensor- can you still get the silicone hoses with a sensor hole in them, pretty sure they used to be a thing

Is this possible from the Apexi? But youre right, probably better to use a new sensor due to the aforementioned stock sensor weaknesses. I've seen the silicone sensor bungs, considering this as an option.

So far it looks like I could get a kit like this:

GM Inlet Air Temperature (IAT) Sensor with Weld Bung and Connector

Brand new GM IAT for any aftermarket engine management system. Perfect for Speed-Density Conversions on the Mitsubishi EVO. Comes complete with a connector, pins for the connector and wire seals.

www.gb-ent.com

And put it on the inside curve of the plastic intake elbow before the throttle. I can epoxy the bung in place for now. One day when I get a metal greddy elbow I can get it properly welded in.
(Pretty sure this just went up in price, it was £25 yesterday... I'd also prefer to find a stepped bung so it cant fall inside the intake!)

 

[marco]

On an apexi? I highly doubt it, basically you need a configurable pwm output and vary the duty with temperature. Just fit a separate sensor. However looking at what your doing, would it be better to have a canbus module in the engine bay taking the readings from ait,ambient, map, and then transmitting them over canbus to the display? Reduces cable runs through the bulkhead?

 

[Jake_rorx7]

On an apexi? I highly doubt it, basically you need a configurable pwm output and vary the duty with temperature. Just fit a separate sensor. However looking at what your doing, would it be better to have a canbus module in the engine bay taking the readings from ait,ambient, map, and then transmitting them over canbus to the display? Reduces cable runs through the bulkhead?

Interesting idea, I think that would be pretty cool, but probably not worth doubling the effort to save a few wires. Maybe when the scope creep gets high enough and I'm programming a complete ECU..

Thoughts on the epoxy for the IAT bung? Is this an acceptable method of boost bung securing?

 

[marco]

I have mine epoxied in. I found a suitable t nut and fitted it so the flange was on the inside.

 

[Jake_rorx7]

I have mine epoxied in. I found a suitable t nut and fitted it so the flange was on the inside.

A T-nut is a very interesting piece of hardware I havent encountered before. I will consider this over the bung, it looks like they serve the same purpose but the T-nut looks like it will work better alongside epoxy. I'm more afraid of things failing and falling INTO the intake than I am of anything falling OUT.

 

[JonFD]

A T-nut is a very interesting piece of hardware I havent encountered before. I will consider this over the bung, it looks like they serve the same purpose but the T-nut looks like it will work better alongside epoxy. I'm more afraid of things failing and falling INTO the intake than I am of anything falling OUT.

Position it at 90 or more degrees to the pipe, so if it does fail, it will fall away not in, or even have in coming up from underneath if your that worried?


Won't it be more prone to fail under pressure, so would be blown out anyway, and then you'd notice a huge boost leak, and hopefully stop etc?

 

[Jake_rorx7]

Position it at 90 or more degrees to the pipe, so if it does fail, it will fall away not in, or even have in coming up from underneath if your that worried?


Won't it be more prone to fail under pressure, so would be blown out anyway, and then you'd notice a huge boost leak, and hopefully stop etc?

Yeah thats true, I'd have to position it horizontal anyway for packaging constraints probably, maybe I can have it pointing downward angle toward the dipstick/ABS.

Failing under pressure is probably likely if it is going to fail. If it falls out I'll have a bad day, but better than the alternative. If I get those T-nuts or a stepped bung from the outside it shouldnt be able to fall it at all so I think the solution is decided! Now to source the bits and get a spare elbow to swap it out.

Thanks all.

 

[Jake_rorx7]

Just to finish the thread. I bought a new elbow, cut off the unused port at the back (the one with a bung over it) so it sits flush with the thicker protrusion. Tapped the resin fiber elbow with (I think) the 3/8 NPT tap for my GM IAT sensor. Put it in with a generous dose of loctite blue and it sits super strong, plenty enough thread depth to hold the pressure. Clears the firewall and MAP sensor easily. The tapered nature of the NPT fitting ensures a gas tight fit.

 

[SullyKP]

And how did the arduino part of the project work out?

 

[Temujin]

Just to finish the thread. I bought a new elbow, cut off the unused port at the back (the one with a bung over it) so it sits flush with the thicker protrusion. Tapped the resin fiber elbow with (I think) the 3/8 NPT tap for my GM IAT sensor. Put it in with a generous dose of loctite blue and it sits super strong, plenty enough thread depth to hold the pressure. Clears the firewall and MAP sensor easily. The tapered nature of the NPT fitting ensures a gas tight fit.

Got any images of where you ended up?

I’m removing the oem iat and have a replacement ready to go somewhere closer to the outlet of the IC

 

[AlexG]

70mm (2 3/4") M10x1.25 Thread Air Sensor Connecting Hoses

 

[Jake_rorx7]

Got any images of where you ended up?

I’m removing the oem iat and have a replacement ready to go somewhere closer to the outlet of the IC

I'll have to get a better photo tomorrow (currently dark out), this is the only photo I took of it because I wrapped it up real nice. Side note, good god is that elbow awkward to wrap nicely. Too many curves.

 

[Jake_rorx7]

And how did the arduino part of the project work out?

Not quite got round to installing it yet, I've been quite lazy and only managed little easy wins like this. The arduino package itself is functional, it just needs fitting and a little bit of wiring. Going to use the power supply for the current boost gauge. I need to figure out how to prop it up on the steering column after I swap it for a standard one. If I could CAD I would make something nice out of a 3dprint I could fix to the top of it, but I cant CAD.

Once I've got it all installed, I'll probably share a how-to and some code, so others can replicate.

 

[Temujin]

Not quite got round to installing it yet, I've been quite lazy and only managed little easy wins like this. The arduino package itself is functional, it just needs fitting and a little bit of wiring. Going to use the power supply for the current boost gauge. I need to figure out how to prop it up on the steering column after I swap it for a standard one. If I could CAD I would make something nice out of a 3dprint I could fix to the top of it, but I cant CAD.

Once I've got it all installed, I'll probably share a how-to and some code, so others can replicate.

Could you utilise one of the upper column cowls which has a gauge mount in?

 

[Jake_rorx7]

Could you utilise one of the upper column cowls which has a gauge mount in?

I considered using my current one until I saw how much the reanemiyeyineina gauges (my current one) cost on eBay. Maybe there are some cheaper ones out there? Could be the move.. I'll have to look around and see if something is cheap enough to cut up. I don't like wasting parts if I can help it.

 

[Temujin]

I considered using my current one until I saw how much the reanemiyeyineina gauges (my current one) cost on eBay. Maybe there are some cheaper ones out there? Could be the move.. I'll have to look around and see if something is cheap enough to cut up. I don't like wasting parts if I can help it.

There are some apps you can get to 3d scan with your phone.
Might be worth trying one on your upper and see if you can extract a decent mesh from it!
Then could edit that to what you want
3d print etc