P0303 Hyundai -

Question

Hyundai Entourage limited 2007.
I get a code p0303. This happens once a week the engine misfires and the check engine light flashes. I pull over on the side of the road switch off the engine and wait a few seconds start the engine again and the misfire is gone for about another week. then the check engine light goes out. What could be the cause.

Answer 1

P0303 Misfire number 3 cylinder

The most probable would be the ignition coil. The worste that can happen is it becomes consistent, and happening at all times. The least of the most probable cause would the the OCV (oil control valve) this would a P0300 and with a OCV code. You can remove the number 3 coil and swap  with a known working cylinder if the misfire moves  you know its the ignition coil

Ignition coil are always the most probable of engine misfires, It is capable of being intermittent when it misfire for one moment and goes away .

Here is a Hyundai 4 cylinder vehicle the owner complaint was a shutter at take off and a stall when the a/c was on. This hyundai did not code a misfire at all, and there was no check engine light on. It was decided to check the sparkplugs when doing so , what was found was  oil has seeped into the sparkplug well this was due to  valve cover leaking oil  into the sparkplug well,This was the cause for the shutter and the stalling when the a/c was turned on.