i got stage three crower camshafts and i know they have a rough idle but i heard that most of the time you have to mess with the ecu to make the car run right with them has anyone heard of that befor

 

Well you need some extra fuel... which means bigger injectors, which means you need a way to control them. ALso you need to retard the spark... so you need an ingition system. You need to do a little more then just mess with the ecu, a cheap way to do it would be getting some injectors, 180lph walbro, safc, and a msd box then getting a dyno tune. But that all depends on what car you have, if you have a 420a thats really your only means to tune the car other then a stand alone. If its a 4g63 then you can get a dsm link and have someone tune it.