OK, This is an opportunity to further the discussion on the proper location/relocation of the air temp. sensor on the EFI 13B. In my earlier thread, RX7Doctor & Max7 started the discussion, and Max7 suggested a new thread to toss the subject around further. So............here we go. Whats the real deal?? Here's the link to my earlier thread.

https://www.rx7club.com/forum/showthread.php?t=447149

 

I replied to that thread as well, so thought I'd chime in here with some additional information about the DEI chamber;

You can tell that Mazda was trying to keep engine heat away from the Dynamic Effect chamber by running the Thermowax System heater hose from the back of the W/P to the TB and using the plastic spacer sleeve to keep it away from the front rotor runners. They have also placed the DEI chamber along the centerline of the engine, when they could have put it right on top of the LIM and had a shorter intake run (but that could be for better torque...). Even though they have tried to shield the intake from heat, you still can't get away from the exhaust manifold/header being on the same side as the intake system inlets - this is going to allow a lot of heat to be absorbed by the intake piping and runners, and heat the intake air charge no matter what you do.

That's why getting the initial air intake temp as low as possible is so important - you are only adding more heat as the air travels through the air piping, TB, DEI chamber, UIM, and LIM, until it finds its way into the engine to be burned.

In regard to putting the Air Temp Sensor (ATS) in the CAI tube - you actually have 2 ATS readings going to the ECU. One is located in the AFM, itself, and is threaded into the housing right next to the air vane. The second is the one near the bottom of the driver's side of the DEI chamber. Together, these two signals are used by the ECU to help determine the best fuel map and for hot-start assist (debatable). You will want to locate these sensors in the best place to get a 'correct' reading on intake air temperature readings, since moving them to ambient air obviously doesn't take into account what the engine is doing.

In other words; I'd leave them where they are. If you wanted to help create a rich mixture at all open-loop fuel mappings (since closed-loop is then reading the O2 sensor for best A/F ratio), then you can likely move the DEI chamber ATS further up the line where it will be reading a lower air temperature.

Will this change performance? Probably not in any way that you'd notice.

 

I would have to agree with LD. I don't see any benefit of moving the sensor. Besides, the ECU is going to run open loop anyway in nearly everycase but cruising. I suppose if you wanted to richen it up above what the default open-loop setting is, you could add a resistor inline with the sensor to 'trick' the ECU into thinking it is colder than what it really is. Too rich will hurt performance as well, so you need to be careful with that.

I am not sure if that sencond ATS is actually used in fueling calculations. The one in the AFM is for sure to account for the density change of air with temp. I don't see how the second sensor could be used for anything beneficial with the calculation. Once you know how much air comes in (using the AFM), you know how much gets to the engine because mass is conserved. I know the second sensor is used for the hot-start assist (bumps up fuel pressure during hot starts). However, if it was only used for this, I would think that they would use a thermoswitch instead of a thermosensor. I have run my car quite a bit with the second sensor disconnected (the wires at the base of the sensor broke). I didn't notice any difference in the performance or drivability of the car. I don't know. I wish I knew for sure what it was doing.

You hear about Honda guys and such adding resistors to get this effect. They claim increased power, but that may be due to the fact that the ignition advance is also controlled by the ECU and is effected as well.

Kent

 

LongDuck, sorry for neglecting to acknowledge your earlier input to the discussion. I do appreciate your technical expertise. Please chime in anytime. Thanks to all for the input. I'm kind of like a technical leach, I take all the "how it works", "why it works" and "how to do it" info that you true techs provide, and attempt (sometimes quite feably) to put it to good use.