I have been reading about the map and its purpose. I appears to read the barometric pressure to figure the elevation and weather conditions. The voltage it receives helps to determine the spark and fuel delivery. When you go wot it will read the same for the baro & map reading if all is working correctly. I figure this is when you have the outside of the manifold and the inside at the same pressure. If you have a boosted car and have 5 psi going into the manifold how does the computer get the correct readings? I assume the O2's are figuring the fuel and air mixture so how do the 2 of them work together to get there mixture? How would you program your car using the added pressure of a supercharger?

 

https://www.camaroz28.com/forums/sho...d.php?t=560089

Basically, the stock MAP sensor does not know if you're at 0 or 5 or 10 psi. You need a 2bar or 3bar sensor to accurately provide a boost pressure reading, and you need to trick the pcm into operating with it.. Refer to the thread above, it's been discussed.

 

This is a very complex question and nobody except the gm computer designers can give you an exact answer.

The map's most prominent purpose is to tell the computer which timing to use at different rpm and maps. The bad thing about stock computers and blowers is that when the MAP sensor maxes at 100KPA then your timing is no longer adjustable for various amounts of boost. The stock computer uses 24 or whatever is in that last cell for anything over 1psi. This leaves a hole in the power band until the car reaches full boost.

In my opinion the MAP has only minimal input to fueling unless your running speed density. The MAF has a huge input on fueling. The MAF will correct for boost up to about 500hp (when it maxes) and then the fuel is simply increased as the rpm goes up. Kind of crude but with a wide band it can be tweaked really close to perfect.

The O2's simply make corrections to what the MAF (or map, rpm, and iat if your running speed density) is telling the computer the correct fueling is for 14.7 AFR. The computer then saves these corrections and applies them in open loop and closed loop. However O2's stop making corrections when you go wide open throttle and are not capable of reading anything except 14.7. Another weakness of the Lt1 computer.

So to fix these weakness's the best way I've found is to run a boost controlled timing retard box, a boost controlled methanol kit and a good wideband to keep and eye on things.

For some good reading check out injuneers site.

http://members.aol.com/InjuneerZZ/ScanMast.htm

 

Making a stock GM LT1 PCM read boost (and add the appropriate amount of fuel + timing) has actually recently been proven to work very good so far in speed density mode + closed loop by simply:

1) Replacing the stock 1 bar sensor for a 2 bar sensor
2) Scaling all of the MAP referenced tables by approximaly 1/2 (only an approximation)

These tables includes (but not limited to):
1) VE tables - CRITICAL
2) Spark Tables
3) Open Loop AFR
4) Injector Flow Rating (cut actual size in about 1/2)
5) BLM Boundry Cells
6) DFCU Cells

Detailed infromation is located two places:
1) https://www.camaroz28.com/forums/sho...d.php?t=560089
2) https://www.camaroz28.com/forums/sho...d.php?t=500809