Over the last 3 weeks my SS sets a P0300 multiple cylinder misfire code at least daily , and sometimes it will set it again after I clear it from the PCM . I really dont know where to look for a problem like that on this car . I took all the plugs out thinking I might see something there , but they all looked pretty good . They all were light tan with a few tiny brown specs on the back of the porcelin . The car seems to be running good , but it feels noticably slower that before , and sometimes it idles kinda lopey like it has a small cam . I was watching my spark advance at idle , and its all over the place ....switching back and fourth like a 02 sensor from like -5 degrees to 12 degrees ....it that normal ? Because the cas seems to running fine , I dont really have any other thing to go off besides the code , and the fact it feels a bit poochier than before . I went racing last night and the best the car would do was a 14.61@97 mph in air as good my 13 sec sig times , and back then I didnt have help of the aluminum flywheel or Borla exhaust .

When I dissconnect the battery , the car seems to have a noticable power increase for about a day . I disconnected it at the strip last night , and every pass after that It went 99 mph , I couldnt get better than 97.1 prior .

I do have clutch chatter witht he new spec and fidendza flywheel , can that noise cause fits with the pcm ?

My ingals torque brace also makes a audible metallic rapping I can hear from inside the car , can that cause fits with the PCM ?

I watched KR when both noises are audible and Im not getting any KR at all . Sorry for all the questions , Im just aggrevated and miffed .

 

You need to get someone with a TECH2 to scan your misfire accumulator/counters to determine which specific cylinder/s is acting up. The plugs may look OK but you could still have a cracked porcelin or other plug issues- but that plug usually is a bit darker due to intermittent fouling. Other things known to cause a misfire on the LSJ include a bad crank sensor (usually sets a DTC but not always), bad COP, or sticking valves due to fuel/carbon deposts that cause the valve to "hang up" especially cold.
BUT
Step 1 - determine which cylinder is setting the DTC and go from there
HTH
WOT

 

definitely sounds like crank sensor to me based on similar but more detrimental problems the Z's were having at one point.

 

Thanks for the info guys .