NJ-LE

Baro value question ... this tuning forum needs some traffic!

I recently started using the GM 2Bar MAP (gm# 12569241). Initial guesses about warm and hot advance were close, my biggest problem was cold idle around the 20°c coolant temp which is fine now. The homebrew tune seems to be good. Looking at the data (Freescan) I noticed that Baro value will increase anytime the running MAP value exceeds the initial (start up) Baro. The Baro value is always stays larger than the MAP. I've had the "Baro Update RPM" (TunerCAT) set to it's max (6375 rpm) for years. Apparently the PCM logic makes the Baro change anyway. I don't see any other changes (advance ° or basic inj pulse width) when Baro changes. What might the PCM be adjusting that I can't see?

TT350

I'm sure you have seen this thread but I'll post it anyway. He talks about the Baro rest.
I'd like to know as well.
https://www.camaroz28.com/forums/com...uction-560089/

TT350

Read post 5 and 6.

https://www.camaroz28.com/forums/com...eshold-721475/

NJ-LE

TT350:
Thanks for the courtesy of a reply. I appreciate it. I had started to review the thread you pointed out but it's gotten so large and many sections are incomprehensible to me. Your second reply pointed me to a section I'd forgotten about. The next PCM change I make will include a Baro Reset RPM value of 0 psig. On second thought, I'll try 100 RPM since Freescan data says key on but not cranked yet PCM RPM value is 50. If the info from the target of your 2nd post is correct then I should only have one baro value which won't change after the engine is running. I'll post back in a few days on the results.

TT350

Thanks, Please post your results. I'm going to start my 2 bar SD tune on a good running stock motor and get it running and driving good N/A then put a set of larger injectors and work the bugs out of that setup in N/A form. After all of this is done it will get a forged motor and a pair of turbos.

NJ-LE

TT350:
Got out this morning with a new tune. (potholes, ice and the 'salt licks' the DOT trucks have dumped on the 'test ramps and straights' kept it tame)
The 100 RPM reset did keep the Baro constant even with positive MAP pressure (as you predicted). I didn't see any other result differences. This is in closed loop. When the roads are clear and clean I'll trying reversing some of the timing table advance cuts I had made to stay knock-free. Just going see if I can add back 1 or 2 degrees.

TT350

That's awesome! Keep me posted on your progress.

NJ-LE

TT350:
Finally got some clear, clean roads. Since the last post, I moved the baro reset RPM to 900 so that stopped or between shifts the Baro value could reset if warranted. I've been surprised because whether a reset target of 100 or 900 RPM the Baro value never changes. It's a reasonable value but I've data captured 11 times now without a change. Perhaps it's coincidental, but it's always been normal for startup Baro to vary by a .1 or .2 every few logs. Looking back, (over 100 logs with the 2 BAR sensor) the longest without change at startup was 4 captures.
I did get to gas it up a bit but the only change was to subtract a degree out a couple of cells in the lower-midrange of the spark advance tables. I couldn't add any back so I guess this is as good as it gets.