Hyundai Forum Members,
My 2005 Hyundai Accent with a 1.6 L MFI DOHC engine has ~85K miles on it. On Monday the CEL came on and when I had it scanned it came up with a P0300 error code (random misfire). Last night I changed the spark plugs (some wear and carbon) and the wires (a little wear), disconnected the battery for ~1 minute, and started the car. I then sprayed the coil packs with water and didn't see any arcing from the packs. I checked for audible vacuum leaks and felt the hoses for any noticeable wear/cracks with no success. This morning I added fuel injector cleaner to see if that would help. The CEL is still on (even after disconnecting the battery). The car starts fine, seems to be running OK without bucking and with sufficient power.

How long does it take for the CEL to clear when you disconnect the battery?

How long does it take for the CEL to clear with normal driving?

Does anyone have any other ideas?

Thanks in advance for any help that you can provide.

Regards,
Kevin

 

Actually, you're supposed to disconnect the battery for a good 10 minutes or so. Not sure if it would work in one minute.

 

Followed your advice, left the battery unplugged for longer and code is cleared. Drove it a couple of miles and CEL is still off, which is promising.

Checked the resistance on the coil packs, both seemed to be about the same ~1.1 ohms, isn't one supposed to be ~0.9 ohms and one ~13 k-ohms?