Out of no where car wont turn on, I hear the main relay for the megasquirt turning on and off during cranking only. I bypassed my ignition switch to rule that out and still the same. I also tried cranking with out the megasquirt connected and the relay is on all the time when cranking as is supposed to. Ecu is a MS2 V3

 

Heres a datalog when cranking

 

Does the car start at all? If so does it run okay? When you crank does the ecu lose sync on tunerstudio?

 

Car doesnt start at all, It was running good a week ago, yes it looses sync during cranking. Could the low temperatures be a part of this?

 

Im not entirely sure. I had similar issues with my starting in the summer time. Eventually it wouldn't sync at all and just wouldn't start. I changed the CAS with a spare one I had and it seemed to have fixed the problem. Just recently however, the sync loss during cranking returned only this time it is not as frequent and my car will eventually start after a few seconds. Im still trying to pinpoint the exact cause, i will let you know if i figure anything out. Hopefully someone else on the forum chimes in. By the way do you notice your starter sounding sluggish at all during cranking or does it sound normal as always?

 

Starter sounds same as always, even if it was a bad cas why would it power off the ecu, I hear the main relay cycling on and off and I also tried replacing it with no results.

 

Maybe feed the ecu a separate direct line for power, then try starting and see what happens? Check if the rpm signal on tunerstudio is showing up when you do this.

 

I didn't had time to mess with it yesterday so today I checked the feed wire and the control 12v to the relay. Hooked up my volt meter and both wires have 12v during cranking. So I decided to hook up the ecu back since I had it in my room for the last two days. Started tunerstudio and engine fired up right away. Everything worked back to normal. I wonder if the temperature has something to do with it since when it started is was in the teens and today is on the 30s, and had the ecu at room temperature when I hook it up. Going to wait until it gets colder out and see what happens. My battery was fully charged the whole time.