Per the title what would you expect? Start and idle well? Drive normally enough under light load? Are the top plugs primary and the bottom ones secondary or are they the same as each other just opposite sides of the piston crown?
Reason I ask is my engine will start and idle happily on the top set only but on the bottom set only it won't start and while on the starter it coughs and bangs and isn't happy. So we're concerned it has a firing order / spark timing issue on the lower coils / plugs.
It's on throttles, EFI, and COP so I'm just pulling relays to disable upper or lower.
Appreciate your thoughts and feedback.
