Hello there. I have been an avid follower of this website and the amount of information has been quite helpful. I have had my 2003 silver s2000 close to 8 months and I am very satisfied by the purchase. However I recently have gotten the CEL light and the whole misfire issue. The codes pulled have been consistent with many posts regarding this issue P1399 and the code reflecting across all four cylinders. The coils and plugs have been all changed an a leak down test was done by the mechanic and revealed nothing amiss. Apparently the mechanic is perplexed as to what the issue is after going through list of things; leak down, valve adjustment, testing of the sensors... What I am finding is that while the car idles there is a slight shake almost like a hiccup which I assume is the misfire. The idle rpm stays steady around 900rpm and bumps up to 1000 rpm when the hiccup occurs. I would like to get this resolved considering the burning yellow light is quite annoying while driving at night. I am in the Arbutus, MD area and would like to take it to a mechanic, less the dealer, who is well versed in diagnosing and fixing the problem. Any help in directing me would be greatly appreciated.

 

Powertrain Control Module (PCM)

 

Or an injector not working properly.

 

The mechanic did say he changed the injectors around but the misfire was still being reflected on the codes.