anyone know which
Scantools
have the feature that they can show the
raw ignition missfire counts in the
Mode $06 data banks?
this article talks about using these missfire counts:
http://www.aa1car.com/library/misfire.htmsample quote
If you find a P0300 random misfire code, it means the misfire is random and is moving around from cylinder to cylinder. The cause here would likely be something that upsets the engine's air/fuel mixture, such as a major vacuum leak, a leaky EGR valve or unusually low fuel pressure (weak pump or faulty pressure regulator).
If your engine seems to be misfiring,
but there are NO codes set
(no individual cylinder misfire codes or no random misfire code),
and you have a professional grade scan tool that can access Mode $06 data,
you can use the scan tool to look at the raw misfire data that is being tabulated for each cylinder.
Normally the misfire counts should be zero or close to zero for every cylinder. The OBD II system will usually NOT set a misfire code until the actual misfire count exceeds about two percent for any given cylinder.
So by looking at the actual Mode $06 misfire data, you should be able to see any cylinders that are showing an abnormally high misfire rate.
For example, if the Mode $06 scan tool data shows zero or close to zero misfires for all cylinders except cylinder number four
(which has a count of say 80 or higher),
that would tell you cylinder number four has an ignition, fuel or compression problem that will require further diagnosis.
end quote
