1987 t2 misfire after long driving
 

So, a little background. I have 3in downpipe, Rtek1.7, 820cc secondarys, boost gauge, aluminum radiator and thats all my mods. Ever since I converted to aluminum radiator, after I drive my car around town for about 40mins, the idle will start to wonder just a little, idles at 900, when issue starts, drops down to 750 and wonders a little. Once I start driving in this condition, it will start bucking and spitting, sometimes its really bad and sometimes its slight but still noticeable

Did replace thermostat with new oem mazda, distilled water and water wetter. My biggest guess is maybe the thermo sensor eventually heat soakes and goes out of range causing it to default

The thermosensor might not be mated properly to the sensor's plug. At the ECU the reading of the Green/White wire for the sensor at pin 2I should read 2 to 3 volts on a cold engine w/key to on and it drops down to .4 volts fully warmed.

Went out last night for some spirited driving, I dont think temp has anything to do with the issue. My car got to 3/4 on temp gauge after long hard drive and the issue did not present itself until I got home and let it idle awhile to cool down, then it started with the wont rev past 1500rpm issue.

When the car starts to have the issue, it holds the rpms at 1100rpm, if that helps

The sensor I speak of helps determine how much fuel is injected so it is important. Secondly, running at 3/4 on the temp gauge is well above the max norm of 1/3 and you are in the process of damaging the engine seals if you have not already done so.

I had the same problem last year and I replaced the water temperature sensor and it ran great after that. I don't know if that's the same sensor your talking about satch but if it is I would totally check into it then.

Did you replace the thermosensor with a unit directly from Mazda, or did you get it from the parts store?

I bled the sytem again with heater going full blast, .9 bar cap, drove around neighborhood a few laps and now sitting and idling in my parking spot for good 25mins, has been sitting at the quarter mark hole time

How long will a car with a blown coolant seal idle before it is blowing out into the overflow?

Been driving and idling for over an hour now combined, still sitting at 1/3rd on temp gauge. Am I safe from the dreaded coolant seal failure? Im making 15in.hg and 25lbs oil pressure at 800rpm after running hour straight

One way to tell if you have a coolant leak is you will eventually have to refill the coolant and the car would be difficult to cold start. As far as other indicators you'll have to rely on someone else.