Default CEL - instant notification or delay?I'm not sure if this is the right forum for this but...
I got a misfire code on cyl 4 and sometimes cyl 1 lately after a flat battery jump start. I've swapped the coils and reset the CEL. The CEL comes back on after a day, sometimes after a week or so.
I'm not sure if the jump start damaged the coil or sensors or failing connectors to the ECU. It could also be clogged injectors, etc by coincidence.
Is there usually a delay for the CEL to turn on for a misfire code? P0304. I've brought it to Honda to check it but they just reset the CEL after spark plug and coil swap too. The light turned back on after 2 weeks. Same code. Sometimes I get different pending codes too. Help?

 

When did you last check valve lash?

 

How many miles? If the code keeps coming back solid for #4 I’d recommend a valve adjust. Also is there oil in the spark plug tube? Seals get brittle with age and can allow oil to leak into the spark plug which could cause misfire. Do a valve adjust and replace valve cover gaskets and seals

 

Guys, Thanks for the responses. I got a replacement F20 AP1 engine from Japan with low mileage (30k) about 3 yrs ago and adjusted the valves until each cylinder got a solid 240 compression. The sparks were all changed at that point with OEM NGK. I only put 7000 miles on it since. So far it has been a solid cylinder 4 misfire but sometimes cyl 1. sometimes pending O2 startup sensor P0410 code.
You guys think it's a valve adjustment issue rather than clogged injectors or fried coils? This all happened on the same day I did a harsh jump start from a dead battery ( was on vacation and didn't start the car for a few weeks when the battery was already weak)

 

If it was a coil, the code would follow the coil. You can swap coil 4 with another like 3 and take plug #4 and swap with plug #2 to rule out plugs and coils. At this point might as well swap fuel injector 4 with injector 1 to see if you can get the misfire to change cylinders.