OBD Operation Summary for 6.7L Diesel - MotorCraftService.com

Functional Underboost MonitoringThe underboost monitor works in a similar fashion to the overboost monitor by comparing the desired vs. actualmeasured boost pressure while in a specific range of closed loop boost pressure operation. If the boost pressuregovernor deviation is greater than the calibrated threshold for 7 seconds, a fault is detected and the P-code is set.The closed loop monitoring window is defined as any inner torque above 50 nm, and any engine speed above1500 rpm. The threshold limit is wider for the underbooost monitor due to transient boost system response,compensation for boost pressure lag, and short term (1-2 second) momentary torque truncation when air pathtorque is kept high, but fueling is limited for component protection.This diagnostic will detect a gross air path leak such as the turbo discharge or CAC discharge tube being blown off,major pre-turbo exhaust leaks, or a turbo stuck in the full open VGT position.Overboost Monitor:DTCsMonitor ExecutionMonitor SequenceSensors OKTypical Monitoring DurationP1247 - Turbocharger Boost Pressure LowContinuousNoneECT, MAP, MAF,7 secTypical Overboost Monitor Entry Conditions:Entry condition Minimum MaximumEngine Torque50 NmEngine Speed 1500 rpm 4000 rpmTypical Overboost Monitor Malfunction Thresholds:If desired boost pressure – actual boost pressure > 50 kPa for 7 seconds, a fault is detected.FORD MOTOR COMPANY REVISION DATE: FEBRUARY 9, 2012 09.01.00.02-PAGE 55 OF 157