I keep missing at cylinder 1 on cold start only its not a plug and not a coil i seafoamed my car it went away for about a month... now its back GM tech put top engine cleaner in it and still nothing changed the coil and plug still nothing....

 

Possibly the dreaded valve gunk on cyl 1 ? Just my first thought sense you said it went away for a month after you seafomed it last time.

 

was thinking the same i used my boresope, cylinder leak down, and compression tester (Im a Kia Tech) to look and its grimmy and everything check out ok but i shouldnt have to do this every month especially on e85. plenty carbon build up too on the valves

 

I had an annoying cold start misfire in Cyl 3 for the longest time. Dealer tried the plug and ignition coil to no avail. Eventually they replaced the injector and the CEL hasn't come back since. Was done under powertrain warranty btw.

 

have you checked the Cyl 1 injector seal?

 

only thing i havent check was injector ill probably do it this week

 

Keep us posted

 

Yeah, you guys beat me to it. I'd say fuel-related issue (i.e., injector/injector seal).

 

When I had this issue, I took it in and the techs couldn't figure it out either, so they added new plugs and put dielectric grease and my problem when away.

**Edit** they too didn't think it was my plugs or coils, but they put new plugs in anyway and added the grease. If it's a situation like mine maybe it'll help.

 

Yeah, i had a problem like this before and found out it was an Injector Seal..

 

finally had it fixed!!! bad injector seal, close call too warranty ends at the begining of the year