Hey Scotty just thought I'd ask some advice. I drive a 2012 Mazdaspeed 3 with 81,000 miles on it. I have had this problem for almost a year now and no one can seem to find or give me a reason why I have this problem. I have a P0300 Code constantly on. At the start of this I had some small modifications installed such as short ram intake, catback exhaust, and a base map tune. I have a Cobb accessport that whenever I uninstalled and ran the stock map the light would stay off. I have recently put on more modifications to where i cannot run a stock map.
Mods list now on car: cobb accessport, short ram intake, full turbo back exhaust(3"), 3.5 bar map sensor, corksport turbo, hks bov, and High pressure fuel pump.
I have replaced injector seals, spark plugs(to step colder plugs). I did 2 different compression and boost leak test and those no signs of promise. I asked the mechanics and they said my coil packs were still good. And through all of that it is still an ongoing problem. I recently have given up on trying to figure out the problem and figured the problem would lead to something greater eventually.
What would you recommend I replace nect or look into replacing. I am now lost on what to do next.
Thank you for your time

Comments (1)
No. 1-1

random misfires can be absolute cows to diagnose. BUT, you have modified the car too much for the software (proven by the light going off with a stock map back on.) You are going to have to find a true tuner pro who can reprogram the computer using a dyno and five gas analyzer to make it run right, no way past that. A REAL PRo tuner, and they are not cheap, or easy to find in most places. Good Luck