Random misfire code P0300, P0301-2-3-4

i hope this writing has enough detail. i am writing about my scion xb with 2azfe 2.4L, i have added tri y headers and sheet metal intake manifold. But after installing Kelford cams 239-b i am now getting random misfire code when the motor is idling or running low rpms. i can tell its not a true misfire it seems to be the small off beat lope of the cams at idle being picked up by the computer. i have use hi perf. cams in other motors like motorcycles and v8s. any help would be great. the check engine light when on turns off the vsc and i think abs. thanks Kelvin

Hi Kevin,

sounds like the OBD monitoring is particularly sensitive to changes in airflow.

the overlap from the cams is probably causing issues with the map signal, you could try moving the sensor pick up to a different location, bringing all cylinders together in a manifold or adding an accumulator in the vac line to damp the pulses out - small dirtbike fuel filters work well for this. But it’s a difficult one to say for sure so a bit of trial and error is needed and what you can do will depend on the control algorithm somewhat.