When I plug my scanner in, it says that my MAP sensor is reading about 2ish inches of HG lower than what the weather stations report it to be. This is with the motor off and key on so it should be reading what the bariometric pressure is right? Would this cause any sort of performance loss if it isn't reading close enough to the real pressure?

 

Well I guess nobody knows?

 

You have to be careful with the barometric pressure that is "announcd" on the weather report, and the true barometric pressure. Often, the "weather" barometric pressure is corrected to sea level. If you don't happen to be at sea level, your MAP "BAR" reading will not match the weather report barometric pressure. I know Katy is not much above sea level though.

 

You are correct in that Katy isn't very high above sea level. So would that lead to a possibility that my MAP sensor isn't reading correctly?

 

The only way to accurately determine that would be to have an accurate barometric pressure gauge sitting next to your car.

One thing to check would be to insure that you are getting an accurate +5V reference signal on the gray wire (pin C) and a good ground on the black ground wire (pin A). Also check to make sure the harness connector isn't falling apart. They dry out and crumble from the heat.