Quote Originally Posted by kur4o View Post
There is an error. Now baro never updates from memory. The value had cleared when you removed power from pcm.
Firstly, sorry for any ignorance, I'm pretty new to tuning EFI.

I did not pull power from the ECM to swap chips. I haven't been - just been obviously having the key off while swapping the chip. Is this a bad idea? Also, I have pulled power via battery and/or ECM fuse, and even so the Baro reading remains. Seems odd, but pretty sure this is what I have observed.

Tell me what fixed value you want for baro. Do you want it to update at ign on engine off. There is also 6 tables that are baro related modifiers. If you set the baro at 55 kp these tables will always read the lowest position.
I think just setting baro to a fixed value of 55 will be all I'd need. Would be nice if it updated at key on, but that's not totally necessary. I'd be happy if it would just stay put at 55kPa.
What do you mean by "read lowest position?" Use the minimum value from the table?

Due to the change in baro from 104 to 55, I had to run the cylinder volume to maxed out, and also use higher values in the open loop %change vs. MAP table to get enough fuel rolling. Took a bit of time to figure out how far I had to go there, but at this point it's somewhat close. So not sure how much baro modifier stuff I should fool with?

Patching anything will not be that hard. Just need to know how do you like the PCM to behave. Do you know some other PCM from that era that use 2 bar map sensor and turbo setup. I can copy the conversion from raw map to baro, so you don`t have to lose these built in baro corrections.
The only thing I know of is maybe the Cyclone / Typhoon trucks. I think that's what the MAP sensor is from. But they are 6 cyl. of course. If you were able to use some conversion there to the LT1, I guess my cylinder volume and other table would need to go back to a more "normal" setting?

There is another conversion from raw baro 3f to some scaled map baro value stored at byte_0158. byte_0158 is used for baro table lookups
So by changing the scaling there, it would alter what values get pulled from the baro table lookups then?