Ok, here is the deal :

Stock FD, after rebuild, all working good yesterday, no problems at all.
Except one of the fans was not working, so i replaced it for working one (it was problem with fan motor itself, i had spare)

Today i installed miata thermoswitch, put everything back together and after turning key on, radiators fans are running - strange, it was not doing it before. No start at all, cranking ok, but no start. Tach is not bouncing (looks like ECU is preventing car to start, no ignition?)

(car has no AC anymore, heater/cabin fan turned off)

Have not touched anything else than fans and fan switch in the back of the waterpump (had to remove alternator of course)

Is there some kind of failsafe mode where it does not run when fan switch is bad or when water temp sensor in the back of the water pump gets disconnected etc?

 

Did you pull the EGI fuse for any reason during your early work? You might make sure that you didn't blow that fuse or any others.

 

no fuses were pulled, i checked EGI fuse and its ok

strange thing is that FANS are running on KEY ON (dead cold engine) which is something what was not happening before....

like if there was some safety mod which would on some (or none) reading from water temp sensor will prevent engine from starting and turn both fans on???

 

according to FSM, this conditon (cranking but no start, no combustion) could be brought by following problems :

- TPS ??
- ECU (tried other one too, no change - i tried even PowerFC with commander and strange with PowerFC it was not turning FANs on, but commander did not turned on either and engine did not run either)
- starter signal ??
- crank angle sensor ??
- fuel pump ??
- circuit opening relay ??
- igniter, coil, spark plug ??

And thats about it....FSM does not mention anything like water temp sensor causing no start at all....but fans turned on are still boggin me....

 

When I've seen that happen, it's been the EGI fuse (IIRC). One of the fuses that you can pull to not start the car when first cranking a rebuild (i.e. to build oil pressure) will make the fans run when turning the key to ACC.

Are you sure you don't have a short in your wiring somewhere? How did you connect to the Miata Thermoswitch? Is that connector still on the sensor properly?

 

Trimmed miata sensor plastic casing to fit in stock connector.

 

do all the interior and exterior lights work? try looking at the MAIN fuse.

 

Yes, lights are working

 

sounds like a fuse to me too, or a relay.

 

um, which one?
havent been to shop today, will have to check it out tomorrow...

strange thing is FANS ON with stock ECU, FANS OFF with PowerFC (no show on PFC commander)

 

fixed....bad contact in the fuse block somewhere at EGI fuse (at battery terminal)

 

Good deal!

 

oh yeah, and PFC worked OK as well once it started up with stock ECU...and miata switch is working too