Upgrade and relocate Air Temp Sensor?
 

I see a lot of posts about people adding a "fast acting" air temp sensor. Just wondering the advantages of doing this other than the PFC display responding faster. Does it effect the tune? Should it be relocated into the cold IC pipe as well?

I notice mine heat soaks like crazy.

Thanks..

Yes your tune can be affected if the reading is wrong like when it reads too high after a heat soak, you go full throttle and your engine will get a leaner mix. I like mine in the pipe coming out of the fmic.

And were can we find this sensor online to buy?

Search this forumn.

Thanks genious

For example ...

https://www.rx7club.com/power-fc-for...nge-fd-842255/

Upgrade the sensor, leave it in stock location.

thewird

This is what I am going to do.

As far as where to buy, I got one off the classifieds. They pop up every now and then. Mine was one of the ones from the group buy. Pretty sure it was a Triumph part.

Even with a faster reacting ATS, it still takes a little driving to cool it down after heat soak.
Thus the stock position is not the best location. Other Mazda rotary engines had it in the TB elbow. The TB elbow and FMIC outlet are the BEST/PREFERRED locations for non alky injection.

Now if you are injecting alcohol into the TB elbow, then the stock location is BEST/PREFFERED
to record the great drop in charge temperature.

Use of an injectant should determine where to locate the sensor.

Ya I agree, even when I had my fraits in the greddy elbow it heat soaked. I have mine in the fmic outlet pipe just before the water injector, was spraying water only though so it didn't really make a difference to the ait readings.

Chuck, I have to disagree. I have tuned cars with the AIT sensor before the TB and the cars have issues with consistency driving in different weather or sitting in traffic. Heatsoaking is the sensor reading correctly. The issue with the stock one is that it will not change for a while since the sensor itself heatsoaks, the fast ait ones do not have that issue and will change when the temp of the air changes. I do 90% of my tuning on the street so I notice these things, you will NOT notice an issue on the dyno.

Here is the a fast ait sensor working correctly in the stock location... Temps drop when airflow is applied and then get hotter, all during the same pull.

https://www.rx7club.com/attachments/...-dyno-pull-jpg

thewird

I agree to disagree with you.

I have had my fast reacting sensor and before that a modified stock sensor in the FMIC outlet for years down here in Houston. When doing this you have to change the Air Temp vs INJ table to compensate for the approximate 10 degrees cooler that it reads in the cooler position. .

Then I set the values in the table to be true linear to keep AFRs the same between seasons. The stock values are crap. They actually lean out fuel for colder weather due to running very rich in heat because the stock IC also was crap.

I have local friends who use my setup without problems.

Chuck do you use aux inj? If so, where do you inject?

I am definitely injecting water .... possibly meth too. Im not sure yet.

I was injecting only water into the Greddy TB elbow right afer where the hose clamps. Now I am trying a mix; 2/3 into the turbo and 1/3 into the elbow.

How is that working out for you?

I still plan to talk to you about tuning my ride. I just started my build, shouldn't be long. I started a "build thread"

I have not got around to retuning AFRs with the new WI mods.
Soo much rain lately.

I know this is an old topic, but I just ran across it and wanted to add my input. I agree with thewird, even though the Fast IAT is mounted in a chunk of aluminum, it's still accurately reading the air temperatures. Even if that temperature shows something higher when we first start the car, or shows a number we rather not see.

The air still has to travel through all that hot aluminum in the UIM where the sensor is mounted, then it has to travel the remaining distance through the LIM before it finally reaches the combustion chamber. Traveling through all those hot intake runners will certainly heat the intake charge a certain amount. In situations where you have very little air flow (small throttle inputs, idle, etc) the manifolds will heat the air even more so compared to wide open throttle where the air speed reduces the time spend in the runners, if the sensor is mounted in the elbow, this heating effect wouldn't be read.

I personally feel the stock location offers the most accurate readings. I do agree with Chuck that the stock correction tables are not accurate at all, and it's best to tune these during different seasons to keep afrs stable. I live a little over an hr from Houston and once I locked in my air correction table my afr's stayed nearly dead on in all weather conditions.

I'm sure running the sensor relocated is completely fine, and can be tuned for. Even a necessity with the stock sensor, but the speed and accuracy of the FIAT I believe makes the stock location ideal. Just my humble opinion.

I've been running my fraits after the fmic exit and then my post fmic water injector was after that. But now I'm tuning 50/50 water meth "boost juice" and I'm thinking it will be best to move my fraits back to the stock location to read the temp change from the meth injection, and I think I'll leave my post IC injector where its at in the pipe connected to the FMIC outlet. Some say that's a good spot for more time for the meth to cool off the air and mix, but some say it's better to inject before the elbow so the air doesn't heat back up by the time it gets there (but this shouldn't make a difference because the air could heat up a little from the fmic to the elbow regardless of when the meth is sprayed) and to get more of the water mist into the engine to suppress knock better.

I'm also spraying pre turbo. I was using a 610cc nozzle @ 200 psi pre turbo and a smaller CM7 nozzle post IC, water only was keeping my knock very very low, but dropping power considerably. When when I started spraying water/meth knock was good for up to 22 psi (and the car felt and sounded much better, the turbo seemed to be working quicker and getting more boost) but with 24 psi I started seeing knock in the 30s, not enough water I'm thinking. so I ordered a bigger nozzle to try out soon from alcohol injections systems, a #10 787cc at 200psi I may try this first in the post IC location, and I may need to get and try a #12 pre turbo.