Misfire Monitor Operation

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.

There are 2 different misfire monitoring technologies used in the 2005 MY. They are low data rate (LDR) and high data rate (HDR). The LDR system is capable of meeting the Federal Test Procedure monitoring requirements on most engines and is capable of meeting the full-range of misfire monitoring requirements on 4-cylinder engines. The HDR system is capable of meeting the full-range of misfire monitoring requirements on 6 and 8 cylinder engines. HDR is being phased in on these engines to meet the full-range of misfire phase-in requirements specified in the OBD regulations. All engines except the 6.8L V-10 are full-range capable. All 2005 MY software allows for detection of any misfires that occur 6 engine revolutions after initially cranking the engine. This meets the new OBD requirement to identify misfires within 2 engine revolutions after exceeding the warm drive, idle RPM.