Vehicle: 2011 Ford E
450, V10-6.8L, Automatic Transmission
Problem: The engine in this van had been
replaced by another shop and the MIL was on. They had replaced
the spark plugs and installed new coils but the misfires
Details: When the customer brought it to
the new shop, the tech retrieved DTCs: P0300, P0301 and P0307. A
static compression test revealed no mechanical problems.
With a scan tool connected, the tech checked the misfire counts
and noticed that the misfire counts increased between 1500-2000
rpm in Park or Neutral and in 4th and 5th
gear between 1500-2000 rpm. Under load, the misfire counts went
to zero or were very minimal – the opposite of what you would
Confirmed Repair: The technician performed
a Misfire Monitor Neutral Profile Correction Relearn procedure
and the problem was cured.
System Strategy: For the misfire detection
system to function correctly, any mechanical inaccuracies in the
crankshaft position (CKP) sensor must be learned by the PCM.
Neutral profile correction learning should be accomplished using
a scan tool any time the PCM, CKP sensor or the crankshaft pulse
wheel is replaced, or when major engine repairs have been
To determine if the neutral profile learning has been completed,
check the MP_LRN parameter identification (PID) using the scan
tool. The PID should read YES if the neutral profile learning has
been completed. If the PID reads NO, complete the neutral profile
learning prior to diagnosing any misfire DTCs.