i have had 2 shops kick the car out, and even the mazda guys wont look at it. heres the deal

Jspec engine
5 speed
tdo19c turbo
emissions removed and blocked off
550cc primaries
680cc secondaries

car runs good for about 3 to 4 minutes... the all of a sudden the coolant temp with JUMP from about 100-214 or so (at once), the fuel pressure will drop (i have full current goin to the pump during this) to 0, and hte car will die. i will have to let the car cool down before it can run again.

heres the thing. the car is megasquirted and after it did this, i turned the car off and back on, and the temp went down from 217-179... something funky. PLEASE HELP!

 

Maybe bad Grounds, bad coolant temp sensor, or the megasquirt isn't properly set up for the thermister that you have. It would be very easy to make a car with any standalone have that problem. Remember that the megasquirt controlls the fuel pump, it percieves this massive temp change and it freaks out. Get an aftermarket temprature gauge.

 

well for one, does the car ACTUALLY get to those temps that quickly? (verified with something other than the car's gauge and sender) Gerenally speaking, even a rotary would take longer than 5 seconds to jump 100 degrees in temperature....not much longer though - haha

Where is the fuel pump voltage being cut from? Meaning, there is no voltage to the pump, but how is the pump wired? does it go through a relay? is there power before the relay? or is the M.S. just shutting it down because it thinks the temps are too high? (as mentioned)

 

The s5 sensor reads a different resistance in the J-specs anyways..

 

The fuel pump should be run by a relay connected to the megasquirt, if not then the ECU can't stop fuel from flowing when the engines stops running. Having the fuel pump running other than for the 5 second prime when the engine isn't running is a big fire hazard.

 

Check your coolant temp sensor and/or water thermo sensor.

If you're "temp" is jumping that erratically, it probably has something to do with one of the sensors

I've seen cars where a bad coolant temperature sensor was the cause of a no-start.

 

i will check into the temp sensor.

the fuel pump isnt loosing voltage thats the kicker. its mantaining a 13.8 voltage all the way through until the car dies then it drops to 11.6 volts...

heres the weird thing, it was working fine when i first got the car, then over time it started getting worse and worse.

ive already replaced:
fuel pump
fuel filter
FPR
primary injectors (one was bad)

 

hey check your fuel pump resistor pack! Its sends a lower voltage at idle to the fuel pump (to lean out idle), and full voltage above idle. thats if your running the factory wire harness (including J-SPEC).

 

I just put a jspec engine in my car and the temp gauge sits at the half way point when warm. Seems to be right to me... How much different should the sensors read?

 

nope, thats been eliminated.


someone mentioned a valve on the throttle body that opens up when the coolant gets hot. the guy blocked that off, but is there some way maybe that the damn thing is still workin?

 

is maybe the sensor running on different ohms,then the sender? maybe? i dont know.. but i know that will give a wrong reading.

 

Both our s5's pegged with the j-spec sensor...

 

everything is "bad grounds" lol

 

the stock gauge isnt hooked up, its running off the megasquirt gauge on the computer, and that computer was set up fro the j-specs resistance.