O.K I'm having some trouble tuning my STS turbo, The engine is running lean, While watching my trims with my hand held programmer I noticed a MAP reading of 5PSI at idle and a high in the mid teens, WTF. Is my MAP bad? I have checked everywhere for a vacuum leak (for the lean condition) with no luck, could my MAP be the cause? Or is it working fine and I'm an idiot? any info on the MAP sensor would be greatly appreciated.

 

The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:

5-volt reference circuit
Low reference circuit
MAP sensor signal circuit
The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.

If the PCM detects a MAP sensor signal voltage that is excessively low, DTC P0107 sets.

If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets.

Do you have any DTC's?

 

MAP at idle should reflect atmospheric pressure minus intake vacuum. At boost, the map reads base atmospheric pressure + your boost psi.

 

also there are different readings as well. metric and sae i think. i think on sae it is a max of 15.

 

SAE = psi, metric = kPa (max 105)

 

I was thinking about the MAP sensor last night and wondered if it was monitoring atmospheric pressure, thank you all for verifying that. I was a little worried, O and no DTC's.