Whenever I start the car I'm getting misfires... car sounds like a subaru and sometimes the CEL will light. It just does it for 15-20 seconds usually, and if I just rev the engine to 4000rpm 2 or 3 times it will immediately go away. It started out only doing it at random times and the CEL would always be misfire on cylinder 1, but now it's doing it almost every time I start the car and I'm getting all codes P0300 through P0304, so random misfires as well as misfires on all 4 cylinders.

I know bad injectors are the first that come to mind, but what else could it be? I read in one place that these specific CELs could indicate a bad EGR, but we only have the secondary air pump rather than an EGR on the S2000. Still the fact that it only does it on start up leads me to believe that it could have something to do with the air pump, since it's only purpose is start up emissions from what I remember.

 

Forgot to mention that it usually does it worst when the engine is coldest. If I've just shut the car off and it's still hot it won't do it at all a lot of the time.

 

https://www.s2ki.com/forums/index.php?showtopic=659930

this link will direct you to what the problem might be.. goodluck!

 

awesome... I'd never noticed that thread. i've been having a weird idle every now and then so I'll check the MAP and TPS first. if that doesn't fix it I'll try seafoam. seafoam was gonna be the first thing I attempted but it's gone up from $5-6 to over $10 so I figured I'd try other stuff first.

 

the process is frustrating but that's the only way you'll know what the problem is. come back if you have mroe questions.