Fuel Pressure Compensation
Capoworks converts modeled cylinder fuel mass to injector pulse time using the injector flow at Injector reference pressure in kPa. That reference is the pressure at which the configured flow was measured. Pressure compensation calculates the injector's differential pressure, then applies:
flow ratio = sqrt(actual differential pressure / reference pressure)
The resulting ratio scales the injector flow rate and, on the primary injector, both slopes of the Ford small-pulse model. Use the injector supplier's rated pressure only when the corresponding flow data is for those same injectors and fuel conditions.
Open Fuel > Injection configuration and select Injector flow
compensation mode. None is for a manifold-referenced regulator and
returns a flow ratio of 1.0. Fixed rail pressure represents a regulator
referenced to atmosphere and uses reference pressure + baro − MAP.
Sensed Rail Pressure uses the selected low or high fuel-pressure sensor.
For a sensed sensor, Absolute uses rail − MAP, Gauge uses rail + baro − MAP, and Differential uses the sensor value directly because it
already measures the pressure across the injector.
Configure and verify the sensor first; see
Fuel Pressure Sensors.
An invalid or out-of-range baro value is replaced by 101.325 kPa. A missing
or invalid MAP prevents differential pressure in the absolute/gauge sensed
paths, while fixed mode substitutes 101.325 kPa for invalid MAP.
Compensation returns a neutral 1.0 flow ratio when the configured reference
is below 50 kPa, differential pressure is unavailable, or differential
pressure is zero or negative. P0090 is raised only when compensation is set to
a sensed rail pressure but no fuel-pressure sensor is configured; a configured
sensor that later becomes invalid falls back without P0090. Log
fuel: Injector pressure delta and fuel: Injector pressure ratio and
reconcile them with a reference gauge.