No Code But Bad Coil?

[wfu1994]

I have a 98 ES300 and it has been idling rough and missing sporadically. I seems to do it sometimes once the enginge gets hot and then I will pull over and let it run for a bit and it will quit missing or sometimes I cut it off and restart and it quits missing. I can sorta hear an arcing sound when I pop the hood. I have tried to get it to miss and then pull it in the garage and disconnect the coils to find which one is misfiring but it wont do it long enough for me to disconnect them. This morning it was missing and when I pulled into the parking lot I cut it off and restarted and it idled fine.

I also have no check engine light. I know if it throws a code then I can determine where the misfire is but I have no check engine light and my mechanic friend hooked it up the other day and there is no code stored. Could it be a coil boot? Or can a coil be going bad and not throw a code? And would a bad plug do something like this? Should I just wait till it throws a code?

Thanks!!

[George_Jetson]

How many miles are on the spark plugs? Is it about time for a tuneup? If you can hear arcing, you should start looking around, pull the coils and see if you can find any signs of arcing.

[wfu1994]

How many miles are on the spark plugs? Is it about time for a tuneup? If you can hear arcing, you should start looking around, pull the coils and see if you can find any signs of arcing.

I did find signs of arcing on the boot of the coil that I replaced. It looked burnt. It did not miss at all for several days then did it again this morning. When I parked the car, I pushed the gas pedal down a few times and it started to idle correctly again. Don't really understand that. Does that sound like a plug or plug wire issue?