see sig. i am swapping in the compcams 226/232 at .05 114 LSA. maybe i am anticipating a problem i wont have BUT? old cam had a very smooth idle. this new cam may exibit some issues with idle being rich and off-idle possibly same. if i read this correctly the map sensor may read lack of vac(due to cam) and assume off idle and enrichen. the 02 sensor may see unburned 02 in exhaust stream and do same(add more fuel). this will all read out in BLM showing fuel added. correcting the BLM to enlean will not help as both map and 02 sensors will override the correction in VE. am i correct so far? seems only way to circumvent possible problem is run open loop in those cells. does anyone know how to prevent closed loop operation at idle? in tunercat i think closed loop occurs as a function of time and coolant temp. where in TC can i prevent closed loop at idle only? maybe will not be an issue? wide band i(nnovative) being installed with cam . please feel free to correct me on this.

 

MAP does not tell the ECM anything except MAP. It uses it to look up VE and as a speed density multiplier. Change the VE tables and all will be good here.

The O2 is not acting in the manner you think. At high vacuum idle there is no negative pressure at the exhaust. I say this because the exhaust pressure must be greater than atm pressure, the intake pressure must be less, any exhaust pulse will be weak because of low rpm(number of bounces), and air must flow from high pressure to low pressure. What seems to be happening with the o2 sensor that when the flow rate goes down the sensor cools off and the voltage is skewed. A heated sensor tends to cure this problem.

HTH

John