Bad Misfire on high RPM
I have a problem.. 2003 55. my car runs fine with lower RPM just cruising but as soon as I jump on it it sputters, backfires, and then misfires badly to the point where it has no power. It feels like its heat soaked but this will happen regardless of outside temperature and on the very first pull. Ive attached a picture of the codes it throws. I have magnaflow primary cats in place of the OEM (they split open a year ago) and I have no secondary cats or resonators just a straight pipe into stock mufflers. When it’s accelerating it sounds like it’s making popcorn lol, then it will also backfire even though I’m not running the RaceIQ pop tune just the normal tune. My exhaust guy said he doesn’t think the cats are blocked since there’s a ton of pressure coming out of the tips when i rev it. It has brand new o2 sensors and that didnt fix it so its not that. Also started doing this right before the 82mm and 630cc were installed, I assumed the new injectors wouldve fixed it but it didnt. Need help.
mods:
raceiq tune
77mm clutched pulley
vrp v2 heat exchanger
82mm throttle body
630cc bosch injectors
secondary cat + res delete
Last edited by maz55amg; Feb 9, 2023 at 02:49 PM.
mods:
raceiq tune
77mm clutched pulley
vrp v2 heat exchanger
82mm throttle body
630cc bosch injectors
secondary cat + res delete
I also agree with the above, I'd start with spark then I'd check your O2s/cats (basing off your codes).
Last edited by ArmoE55; Feb 6, 2023 at 12:23 PM.









