Misfire Monitor Operation: Notes

WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2004 Mercury Sable, 2004 Mercury Mountaineer, 2004 Mercury Monterey, 2004 Mercury Marauder, and 2004 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

There are two different misfire monitoring technologies used in the 2004 MY. They are Low Data Rate (LDR) and High Data Rate (HDR). The LDR system is capable of meeting the FTP monitoring requirements on most engines and is capable of meeting full-range misfire monitoring requirements on 4 -cylinder engines. The HDR system is capable of meeting full-range misfire monitoring requirements on 6 and 8 cylinder engines. HDR is being phased in on these engines to meet the full-range misfire phase-in requirements specified in the OBD-II regulations. All engines except the 6.8L V-10 are full-range capable. All 2004 MY software allows for detection of any misfires that occur 6 engine revolutions after initially cranking the engine. This meets the new OBD-II requirement to identify misfires within 2 engine revolutions after exceeding the warm drive, idle rpm.