E-Force Boost Measurement (Installing A Boost Gauge Or Pressure Tranducer)
1. The TMAP sensor mounted on top of the manifold at the rear of the driver's side, outputs a 0-5 volt signal through pins 1 & 2 (pin 1 is signal & pin 2 is signal return,) that can be converted to an absolute pressure reading using the below calibration curve. Use of this signal requires an ambient pressure correction for calculating boost pressure.
|CAUTION: Never cut into the vacuum lines leading to the fuel rail pressure sensor and bypass actuator, on the driver's side of the manifold, for the purpose of tapping in a boost gauge. Interruption of the vacuum signal to the fuel rail pressure sensor can affect the fuel pressure reading to the PCM, which can result in engine failure! Furthermore, this port reads pressure before the intercooler, and therefore is before the inherent intercooler pressure drop. Readings from this port will always be approx. 20% higher then what the engine actually sees.
If measured properly on an otherwise stock 4.6L Mustang GT, your boost readings, utilizing an electronic transducer or MAP sensor, on a dyno, should be comparable to this boost curve, shown below, collected from a recent dyno test here at Edelbrock. If you install a mechanical boost gauge in your vehicle, you will see a steady 5 PSI on the gauge during full throttle acceleration on the street.