Resolved Alternative IAT sensors for speed density

[Kryndon]

So it seems 99.9% of people just run the GM IAT for their SD setups however I have been spending hours trying to locate one and it's proving impossible. Being in Europe, it seems this sensor is not sold new by any retailer or parts store. And I have also checked most of the GM vehicles for parts that these come on and again there are none in my country or near.

So the question is, could I get away with finding a similar style IAT sensor let's say from a Honda or a Hyundai? I'm talking about a brass-threaded cage style sensor that I can thread into the bung pre-TB? My worry is whether the voltage scaling will be the same. As far as I know, ECMlink only supports the GM IAT sensor as an input.

Has anyone tried running a different IAT for their SD setup and if so, could you please share the part number or what car you got it off? Shipping from the US or China to me will take 2 months...

 

[1990TSIAWDTALON]

I ran a postage calculator from my post office to Bulgaria just to see what shipping a 1 pound item would cost (I know that sensor doesn't weigh a pound but figured it that way).
Here is what I show as far as delivery times and costs.

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[Kryndon]

Thanks for checking Marty, but I'm still on a budget and time constraint. Shortly after I posted this I found a part number for a 1991-1996 Jeep IAT sensor which looks identical to the GM one, comes on the 2.5 and 4.0L gas motors. Even uses the same connector. That one new is even more expensive than the GM one HOWEVER I managed to find a Jeep like that for parts here in BG and the guy is gonna send me the sensor + connector for $13! I will wire it up when it gets here and test it with Link. If everything is good and it reads properly I will come back to this and let you guys know if it's a valid alternative!

 

[1990TSIAWDTALON]

What a good story. Yes please let us all know if it functions like you think it should.

 

[bastarddsm]

They use the GM sensor because it has almost the same scaling as the mitsu one in the maf. it's possible you could hack apart a mitsu maf and make your own if you are on that much of a time money crunch

 

[We're on Boost]

I managed to find a Jeep like that for parts here in BG and the guy is gonna send me the sensor + connector for $13! I will wire it up when it gets here and test it with Link. If everything is good and it reads properly I will come back to this and let you guys know if it's a valid alternative!

This is supposed to be the resistance chart for the Jeep MAT (manifold air temp) sensor, according to the Chilton manual for 1984 - 1998 Cherokee, page 4-27, US and Canadian models. Might not do you any good and it might even be wrong, but here it is:

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[DSMPT]

AEM air temp sensor is supposed to be identical to the GM IAT sensor. Probably you can easily find one in Europe, no need to ship from outside. I think this was mentioned somewhere in ECMTuning website.

 

[Kryndon]

This is supposed to be the resistance chart for the Jeep MAT (manifold air temp) sensor, according to the Chilton manual for 1984 - 1998 Cherokee, page 4-27, US and Canadian models. Might not do you any good and it might even be wrong, but here it is:

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I went through most of the Jeep related topics concerning measuring their IATs and it turns out they switched sensors in 1990. From 1984 till 1990 the electronics used on Jeeps are made by Renix and the IAT at 20*C measures ~12000 ohms like in the chart you linked. However from 1991 till 1995 the IAT is straight up sourced from GM, the same part number, and reads the exact same values as the GM one (duh). At 20*C they both read 3400 ohms. Here are the two charts:

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[We're on Boost]

Here are the two charts:

Thanks! So I just saved those to my computer in case I ever need that info for my 1994 Jeep Cherokee

 

[1990TSIAWDTALON]

What do ya think, resolved now? Happy that they are the same, good informaiton!

 

[Kryndon]

Marty let me confirm all this by actually testing the sensor first and seeing how it reads in Link, then if it's all the same we can mark it as resolved.

On a related note, does anyone know if there is a way to manually set the resistance scaling for the IAT sensor in ECMLink? Let's say for example the guy ends up sending me the wrong (older) sensor, could I somehow account for the different values/scale?

 

[We're on Boost]

On a related note, does anyone know if there is a way to manually set the resistance scaling for the IAT sensor in ECMLink? Let's say for example the guy ends up sending me the wrong (older) sensor, could I somehow account for the different values/scale?

I don't think so. Maybe there is a way, I don't know about it.
My understanding of it is that ECMlink has that for some of the sensors that are linear. Because 2 points define a line, so it's easy. Just key in your 2 points and you got the whole relation accurately.
But these temp sensors that are thermistors, they are non-linear, so you would need a bunch of points to even approximate it.

 

[Kryndon]

Right so small and unfortunate update. I received the sensor guy had 6 of 'em which all read the same resistance at room temp (20C) and they were all from 1991-1996 Jeeps (Wranglers, Cherokees etc) and CONTRARY to the graphs above, this sensor reads like one from 1984-1990. I have no idea what the hell is up with this discrepancy. I used a thermometer next to the sensor with it hooked up to my ohmmeter and heating it up gradually with a hot air gun. It went up to 70C and reads exactly like the early model graph. Clearly this will not work the same as the GM one, if it works it will simply read way higher and I will be pulling all the timing...

This is turning more into a Jeep-related thread however I want to exhaust all the possibilities and reach a conclusion of either of these sensors can work with SD. I will report back once I have more details.

P.S @We're on Boost if it's not a big hassle could you measure your Jeep's IAT sensor's resistance at room temp and tell me how many Ohms it reads? You mentioned it's a '94. Which motor has it got?

 

[We're on Boost]

P.S @We're on Boost if it's not a big hassle could you measure your Jeep's IAT sensor's resistance at room temp and tell me how many Ohms it reads? You mentioned it's a '94. Which motor has it got?

It's got the 4.0 liter inline 6 cyl.
I'll go out later today and take a look at the sensor to see if I can get the plug off of it without damaging anything!

 

[We're on Boost]

Well that went easier than expected. The connector came off and went back on real nice and easy just like it should. And nothing tricky about the latch - it's obvious how it works unlike some of our DSM connectors.
Anyway bad news I think. I measured 11.34 K ohms with a Fluke 87 meter. That was at 70 deg F (21.1 deg C). Everything under the hood measured 70 deg F with a Milwaukee infrared temp gun. Nothing tricky going on with the temps either. Jeep is outside but in the shade and hasn't been driven for a few days. Ambient air temps were about 71-72 deg, 2:30pm, max air temp today will only be about 73 deg, overnight low of last night (51 deg F) is long gone. Even the concrete slab under the Jeep was at ~70 deg.

So that's it, 11.34 K ohms at 70 deg F.
Sure looks like the one you didn't want.

The sensor and connector looks just like the ones Rock Auto shows for the 1994 Cherokee 4.0 liter:
https://www.rockauto.com/en/catalog...r,air+intake+/+charge+temperature+sensor,5072

Here are pics of mine, with and without the electrical plug:

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[Kryndon]

Alright big and fortunate update! My car is now fully running Speed Density on a bunch of old sensors!

So I had the guy send me the other sensor he had which is the older style sensor with a pigtail connector attached to it, from a 1984-1990 Jeep Cherokee / Wrangler. Those use the SAME exact scale as the GM IATs from that era, in fact the sensor itself is built by GM but has a Chrysler number on it. The part number is 3300 2382 or the aftermarket equivalent is Tomco-12134.

I had to splice in a different two wire female+male connector and then splice into the MAF wires. When I had everything hooked up I used a heat gun while ECMlink was logging and I saw a nice gradual increase from ambient 27*C up to 101*C. It dropped back down quickly as it cooled. Not too shabby for a 30+ year old sensor!

So in conclusion this alternative IAT sensor CAN be used perfectly with ECMlink! This would be mostly helpful to us Europeans since there are lots of old Jeeps laying around with these sensors but not so many Firebirds, Trucks or what have you from GM. Sensor cost me $10 shipped, bung cost me $15 for machine work + welding, and the 3bar MAP sensor was also $15. All in all this SD kit cost me under $50! Not bad compared to having to wait weeks and paying import duty and shipping fees from the US.

Thread can be marked as resolved, hope it helps somebody!

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[We're on Boost]

Good deal!

 

[Spleen8urLSX]

AEM air temp sensor is supposed to be identical to the GM IAT sensor. Probably you can easily find one in Europe, no need to ship from outside. I think this was mentioned somewhere in ECMTuning website.

This is what I was thinking, along with Haltech, Holley, and LinkECU I believe also sell the AC Delco IAT as their own just as AEM does. I’m pretty sure all of the companies named have presence in Europe.

That aside though, to conserve a buck that’s slick the jeep iat sensor worked out! That was some quality research you put in on that one, good stuff.