I have been tuning my MS3x for the last week and there is an annoying issue that I haven't managed to fix. Sometime, right after startup (doesn't matter if the car is hot or cold), the megasquirt will close the idle valve abruptly stalling the engine. If I try to restart the car right after it usually does not do it, the idle valve slowly close to bring the RPM down.

Any idea what could cause this? In the attached log you can see at 33 seconds the idle valve closing from 36% duty cycle to 20% duty cycle. At 40 seconds I restart the car and you can see the idle valve slowly closing after

 

Are your closed loop idle initial values too low? I forgot how that table is scaled but it looks like the values between 700 rpm and 900 rpm would interpolate to something around 20%

 

Under closed loop I have the Crank to Run Taper setting set to 5 seconds, shouldn't it gradually decrease the duty cycle to 20% instead of going to 20% straight away?

 

Yes, I am just wondering as your min values for your idle valve are starting at 16%, and 20% is barely opening the idle valve at all. You might want to give the car more air when its warming up so it doesn't stall, that's sounds like what is happening. Depends on how far in your idle bypass screw is

 

One more question, is there a way to know if closed loop was active at a specific time with just the log?

 

What firmware are you on? If on the latest, could be your engine states not set correctly.