I have an EcuMaster Black ECU, and when I try to start the car, the battery voltage fluctuates between 10.5 and 10.6. Do you think this is a reason the car won’t start? Does the ECU have any intervention in this matter?
Was it starting before without issue? If you are reading 10.5-10.6 while cranking, it shouldn’t be an issue. If you are reading 10.5-10.6 just keying on the car, you likely won’t have enough voltage to keep the EMU powered up enough while cranking the car over.
Previously, the car was already running smoothly. It does this from time to time. When I boost the battery, when I supply the battery,the car starts up easily.
That alone should tell you that you have a low voltage problem. You may need to check your charging system and see if you have a parasitic draw somewhere that is too much.