The intermittent no spark can be due to a bad crankshaft position sensor.
A faulty crank sensor will not send any signal to the ECM and there will be no spark generated.
Heat and vibration from the engine can make the crank sensor loose its internal calibration and that can send in correct data to the ECM. Which can trigger no spark. It can also shut the engine down, if it was running.
You might find these articles helpful:
I have attached diagrams for your reference.
Please let me know of any questions.
Images (Click to enlarge)
Wednesday, September 22nd, 2021 AT 7:40 PM