well open loop tuning seems to be the talk on here right now.

i just recently got a wide band o2. i was doing some logging with it and noticed that when my blms were at 128 my air fuel ratio was anywhere from 15.5 to 17
and it was running like crap
im running a fairly big cam so i figure i'll give open loop tuning a shot
i've had great luck with it so far, got my idle pretty steady, added almost 6 kpa(increased vacume)
i got it running around 13.8 at idle and 14.5 to 15.1 at part throttle. but when i let off and leave it in gear my afr jumps to 18 and it starts popping.
should i just be adding a bunch of fuel to the lower kpa in the open loop afr table?

also i cant get my timing at idle to stay still.. its only jump a couple degrees but cant figure out why. i set the timing at 800-1200 rpms in the 50-70 kpa range all to 28. also set the closed throttle advance to 28.

oh by the way im using tuner cat

 

Ok as far as the popping on decell and the 18:1 AFR, this is normal, the PCM cuts off the fuel on decell and there is no need to have a good AFR because your not asking the engine to idle or make power, you are slowing down.

As for the IDLE timing jumping around this is also normal, the cause of this is the PCM has a table to refer to adjust timing to help maintain the correct idle. On this same note the BASE timing tables will not be followed exact, teh PCM has many timing VARIABLES in timing. Most of them we can see in LT1_edit and the Newest version of LT1_Edit for OBD2 has just released the update that allows its users to ADJUST the "Maintain idle timing" tables. I do not know if this is or will ever be available in OBD1. I also just read you are using tunercat, Tunercat does not have the " Maintain Idle Timing" function to my knowledge. But it is prefectly normal for your timing to jump around a little at idle, it help keep the big cam idling smooth as possible.

 

cool thanks.