Zero Fuel Calibration

WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

Zero fuel calibration is an algorithm used to detect deviations in individual fuel injector performance from nominal. In an overrun decel fuel shut off condition, fuel rail pressure is set to 3000 kPa (4351 psi) and small injections are made from a single fuel injector. The observed acceleration in crankshaft speed is detected and compared to the expected acceleration. If the observed acceleration deviates from the expected acceleration by more than 50%, then an additional routine is called that adjusts the injection energizing time until observed acceleration matches expected. This information is then used to adjust all injections on that fuel injector for a correct fuel delivery. If the absolute energizing time observed for the test injection to yield the expected acceleration exceeds minimum or maximum limits, a DTC sets.