When I did the conversion from 89 MAF to 730 ecm and code $59 for my turbo motor I reused my 89 IAT sensor. Most websites list the same part number for 87-92 TPI cars so the same sensor is used in 730 cars I guess.

The IAT sensor is the metal cased one that looks just like the CTS coolant sensor.

I have my sensor mounted in the Victor E EFI manifold on the number 7 runner since there is a port there for a sensor.

Over the last year I noticed it doesnt seem to do anything. Car runs fine with it there but the readings dont really change and seem hotter than they really would be. I think its heat soak and thus the readings are not correct.

For instance, at the track on my last run, I start it up and it reads 154 deg F. IT was a hot day and the car was overheating most of the day but I had a little while to cool down. I figured the air would be closer to 90 deg since outdoor temps were in the low 80's. Coolant at start was 162 deg F. So at the end of my run the IAT is reading 150.6 deg F. So it went down a few degrees after 10 seconds of 16.5 psi boost coming in?? IATs normally go up unless my intercooler at 140mph is realllly doing its job. For reference, coolant temps were 182 deg F so it went up 20 deg.

I started thinking about this and realize the turbo GMC trucks that use code $58 and $59 use a open element plastic IAT sensor.

Should I be using that sensor instead and mount the sensor in the intake air piping to the throttle body? I want to know what my IAT's are and cant trust the current setup. Is that sensor similar to these fbody metal ones? Do they function the same way signal wise to the ECM? Thanks for input

 

Well in my limited experience with the IAT sensors, GM places them in the air cleaner box(V6 cars) and in a similar place on the V8 cars as well. The reasoning behind this is simple. It is placed there to get a more true reading on the incoming air temp. It is true that the later models use a plastic sensor mounted in the intake ducting. It seems to me that the plastic housing sensor would be less resistant to heat soak than a metal cased one. If you have yours mounted on the intake manifold, it is probably getting heat soak from the hot engine. I would move it to the intake ducting as close to the air filter as possible.

 

That is precisly why I don't use the "closed element" IAT sensors.

Swap to the open element and you will see a quicker and sometimes drastic change in IATs.

On my car I will notice that they will be slightly above ambiant, but get into boost and the temps rise quickly, get out of boost and drop quickly. This is a non-intercooled set-up currently.

 

Yes the closed element sensors heat soak like crazy. All mine look like they have a plastic basket around the element, hence the name open element. If you don't have one, i would recommend getting one. They are not expensive.

 

So it doesnt matter what sensor i use as long as its an open element plastic one? Not exactly how code $59 IAT functions differ from fbody stuff. I was going to try and order a syclone sensor since its the correct application.

I gotta browse thru the IAT based tables in the code to make sure that when I swap to one of those sensors, my tune does not vary from where its at. I got a few bungs to weld into the intake air pipe after intercooler. I hope to put it there.

 

ALL IAT sensors used in these applications use the same value of resistance vs temp, so whether you use the closed element, open element that threads in (like the closed element but with the plastic "basket" around the sensor), or the all plastic "push in/clip retained" IAT, the values for temp to resistance will be the same, and if the readin were the same across all the sensors it would not change the tune. The tune will change however, due to a more accurate (IMO) reading from the open element sensor.

FWIW, my IAT, or I guess more accuratly "MAT" (Manifold Air Temp) sensor is mounted in what used to be a hole for cold start injector, which is located just after the throttle body in my Datsun (Nissan L-series engine). I'm a fan of reading the temp of the air as close to the cylinder as possible, and seems to work well for me.

I'm also using $59.

In the picture below you can see the IAT/MAT threaded into the top of the intake just after the TB, but before the intake branches off to the cylinders.

 

I was thinking of putting it just in front of the throttle body since I have no other spots in the intake manifold or intake elbow. I was hoping it would be abit farther away from possible heat soak issues.

 

Honestly, with the open element sensor, heat soak is virtually gone. I've compared intake metal temps to what the ECM is reporting (IR temp gun for metal temps), sampling the metal directly beside amd even theh base of the IAT/MAT sensor and saw a large difference between, at least enough to see that heat soak was not a concern.