i have a 2001 prelude base model 5spd, mods are i/h/e and apexi v-afc.
the codes are:

P0301B-misfiring cylinder #1
P0302-misfiring cylinder #2
P0304B-misfiring cylinder #4
P0300B-mutiple and random misfiring

i have replace the cap,rotor,wire,plugs,and ignition coil. the car was misfiring consistantly but after all the replacement it only does it every now and then. i am baffle and not sure what to do. i have work on cars before but never ran into a problem like this. any help would be glady appreciated. thanks in advance

 

hello, sometimes those codes are related to malfunctioning EGR system. for instance if you EGR passageways are clogged all the flow of the exhaust air will go more to one cylinder than another causing a misfire, but that would more likely be a single cylinder misfire than multiple (because the other ports are clogged). EGR could be opening more than it should, but that should set an EGR code. i am not completely sure how your cars EGR system works. Another thing i've heard (i think this was for hondas) belive it or not if you put an aftermarket alternator belt on some of them it will set those codes because the belt is the wrong size so it makes the crank shaft change speeds barely so the crank sensor will see that and set codes, but it will run just fine, just set codes. really, im not making that up. if you havent figured the problem out let me know and i will see if there are any bullitens on it and ask the guys at work.