Recently I've been getting CEL's on cold starts (random misfire code). Usually the CEL will go away if I restart the car once it's warmed up, but sometimes it'll stick around.

I brought it into the dealer, but they couldn't dupe the issue. They reset the ecu and told me to come back if it happened again.

So it happened the very next day, except the problems were a bit worse. Engine sounded very rough, and the CEL started flashing. RPM's stay constant however (no strange fluctuations). Went away once I restarted like above.

Brought it back to the dealer. They still can't find what's wrong with it. They've run compression tests to see if it was a problem with the head, but that test came out fine....

I've searched around, but I feel like the dealer would have figured it out already if it were a spark plug or coil issue.

Soo, hoping the guru's here have any idea what it could be? The only thing they could think of was that the valves are too tight, so they're going to adjust that. Does that sound plausible? Valve work was done about 12k miles ago.

 

Just a follow up for future reference, adjusting the valves seemed to fix it. I have no idea how valves magically over tighten, but they readjusted them, and the car is fine now. It's been about a week.

 

Did they adjust the valves with the car dead cold? Usual procedure is to leave the car in the engine bay overnight, so when the tech shows up in the morning, it is nice and cold and ready to be worked on. If left outside then they should roll it inside the shop, but not started. If they did it as soon as you showed up I can see them botching up the job.