Quote Originally Posted by Iron Indian View Post
How can the EVAP effect tuning? I've thought about getting rid of mine to clean up the engine bay, other times I figure I shouldn't dick with it.
During an EVAP purge the trims will go very negative as it balances out the mixture with the extra fumes its pulling from the tank. That can throw off your tuning results. While VE or MAF tuning you should unplug the EVAP solenoid.