I have read every thread that had something to do with this code and no one every found a solution. I have a 2003 with about 95000 miles on it, every since the weather has been getting colder, I have being getting misfire aleast once a day. This is a misfire in which you can hear it drop a cylinder, as soon as it misfires the cel light starts flashing. This has happened while driving or when just starting it up. I know it could be several things, just seeing what you guys think, like I said you can hear it drop a cylinder and it started a lot more now that it is cold. It has been going on awhile now, so now it's getting annoying.



SUGGESTIONS PLEASE

 

dropping a cylinder (or more) is more than a misfire - the misfire is just the resultant code you get

things that can cause it, in no particular order

1. bad plug(s)
2. bad coil(s)
3. intake manifold leak(s)
4. improper alternator output
5. bad/dirty injector(s)

not sure what significance the weather would have, but I'd start with checking the plugs and measuring the coil resistance of all units. If you have a spare set of coils, swap 'em in one by one and see what happens

 

Thanks a lot for the help. When checking resistance, is there a plus or minus of what you should be looking for, or just make sure they are similar?

 

in the factory service manual, section EC-255. Start there, it will give you the various procedures to check everything. If you don't have the FSM, let me know

 

it's funny you have this code also, my 03' G35 coupe has it also and I changed out the plugs on Mon. now I don't know where to look. It's only rough at idle. while i'm driving everything seems fine. i'd hate to buy 6 new coils because i'm not sure if that will be the fix. can anyone help and where should i look next? thanks.

 

I swapped my coil packs around and same problem. The cel blinks twice, I am curious if that is telling me cylinder 2. If that is the case, I am now going to switch injectors. See if the misfire will follow

 

individual cylinder misfires have their own dedicated codes

 

My guess with an intermitten occurence and its volitiliy as something electrical. Have you double checked all of the ground wires? If those check out I'm with Adam on those suggestions, packs, plugs, leaks and injectors.

 

Wish you the best of luck finding the problem, I've got one of my own including the P0300 code. However I think mine has more to do with the timing.