Engine will fire once then not for two or three revolutions then fire once again. It had a E27 Pos error code that was addressed. Changed plugs , coils,. Then changed the crank and cam sensors as well as the small harness to them.He ran diagnostics and checked all pressures sensors and all seemed good. After he switched ecus and other components from another running machine he thought it needed a complete harness. That was replaced and the problem is still there. It has no codes and when you try to start it fires once then cranks three more times then it will fire once. It fires at a regular rate but will not fire between the three revolution interval.