Ok, here's my problem(s). This has been happening for a bit over a year know and i'm getting soooo sick of it i want it to stop. Overall the car runs great, but every once in awhile (but becoming more frequent), my car will do a few things i will try to describe the best i can. This happens sporatically and under any circumstances, doesn't matter if the car is hot or cold, driving or idling, or anything else i have figured out.
Problem....i'll start with at idle, the car will stutter and sput and almost die, actually sometimes it does die, for 3-10 seconds then puff out some black smoke and seems to be fine. Problem.....while driving, under "decent" acceleration the engine will completely cut out, again for maybe 3-5 seconds puff some bluish smoke smells like gas and is fine.
Now for over a year i've done various things trying to fix it; plugs, wires, coils, ignitor..... and recently i just bought a Commander holder for the PFC which i just have had sitting in my glove box since i got it tuned. So i noticed that before EVERY time it does this the Temp Sensor value blanks out like - - - - - doesnt read a value at all. then it will jerk/sputter/cutout or whatever for a few seconds the value will come back on and the car will run great again.
So does it sound like the temp sensor is bad? or is it something in my PFC? i'm running out of patience with this car, it used to happen once a month or so, now it happens almost every time i drive my car.
Thanks for any help or advice.

i will give you a run down on my mods just in case that may make a differance; stock engine/turbos, pretty much everything else lol. intake, dp,mp, n1 exhaust, main pulley, greddy FMIC, koyo rad, supra fuel pump, PFC w/commander, and some small stuff i'm prolly forgetting. made 330whp@ 12 psi.

 

An intermittent engine coolant temperature sensor can cause the symptoms you've described.



This sensor's resistance becomes higher as the engine's temperature gets colder. Therefore, a brake of the sensor's internal sensing wire or the wire between the ECU and the sensor itself, as well as just a poor electrical connection somewhere in the circuit, causes the resistance to go up. The effect is to tell the ECU that the coolant temperature is much colder than actual and cab easily by interpreted by the ECU as an engine temperature well below zero.



When mine was failing I found its measured resistance to be 30% high at 10 degrees F, but within spec at the rotary’s normal operating temperatures.



This is a easy repair and you can find a number of posts on the subject. For example, https://www.rx7club.com/forum/showthread.php?t=398679

 

sounds like he was getting readings of -38 tho, mine totally blanks out. but i have seen the - - - - "jump" to -38 then goes back to - - - -. but the way it sounds the sensor is pretty cheap and simple to swap so i will do that and hope it finally fixes it. Thanks FDjunkie

 

had the same problem it will read negative readings and then go blank. i replaced the intake temp sensor under the upper manifold and never happened again. mine too would happen at any given time. it was running rich as ****.

 

mine would jump from 30c to 4 to 11 to 15 it was going crazy...ordered a new one from malloy and replaced it and dont have that problem anymore...