MAP Sensor Question

[varmint2506]

Any of you guys know how to modify the MAP sensor output on an '89 5.7 to fool the computer. I'm getting an EGR low pressure code due to the VERY free flowing exhaust I'm running. I know the MAP sensor spits back a voltage range to the computer which adjust for lean/rich mixture. The problem only exists when cruising at low mph and low rpm's. I'm not too worried about the problem since the truck runs great.

 

Any ideas besides just ignoring the CEL?