The "map solenoid" is used to switch the map sensor from reading manifold pressure to reading atmospheric pressure. This switch is done while the engine is running to allow the ECU to adjust for changing atmospheric pressure which is usually caused by changes in elevation. IE going up a mountain in your car. Removing the solenoid might be fine if you never ascend or descent mountains but I'd recommend leaving the solenoid functional for best drivablility from your car.
The Baro Read Solenoid is used by the controller to update barometric pressure on the turbo vehicles for precise fuel/timing control.
The controller controls fuel/timing by comparing the difference between engine vacuum/pressure to atmospheric pressure.
This is known as Speed Density Fuel Control.
MAP = Manifold Absolute Pressure
With the TBI and turbo cars baro info is read when the key is turned on and there is no vacuum/pressure at the Map Sensor.
The TBI cars do not update baro info again until the car is shut off and restarted.
The turbo cars need updated info so fuel/timing will be correct under all conditions.
When driving at steady throttle/no load conditions the controller will actaute the baro solenoid which will shut down vacuum to the map and bleed off any vacuum in the line.
The controller will now read barometric pressure and then allow vacuum to flow to the map sensor.
So to answer your question, the Baro Solenoid is needed.
Wow you guys. Awesome answers! Most appriated! My remember my teaching mentioning a story of a solenoid that went bad and the car would run bad..he found out it was the baro sol was sticking which gave a inaccurate reading to the map..messing up like u said "timing".. thks!
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