Hey guys,

I just bought a G35 2008 sedan, i upgraded to a custom built catback system no resonator and magnaflow mufflers. but it was too loud so i added a cheap resonator to reduce the drone and sound, now the RPM is not steady on idle it fluctuate and check engine light is on ? any ideas

I i tried the ecu reset procedure from this forum i couldn't get it right would that help if i reset the ecu, Throttle Valve and Idle Air Volume.