Autotap: Total Misfire Current Count???
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TECH Resident
Joined: Jan 2004
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From: Castro Valley, CA
Autotap: Total Misfire Current Count??? I've been having some problems with burnt spark plug wires.
After replacing a cracked wire and logging some data on a couple runs, I see my "Total Misfire Current Count" is still at zero.
That seems too good to be true. Is there another parameter that I should be tracking that will give me better live info to help me diagnose which wires might be losing function?
Thanks in advance for any help,
Rich
After replacing a cracked wire and logging some data on a couple runs, I see my "Total Misfire Current Count" is still at zero.
That seems too good to be true. Is there another parameter that I should be tracking that will give me better live info to help me diagnose which wires might be losing function?
Thanks in advance for any help,
Rich
First, are you sure that misfire detection is still
functional? On aggressively modded cars (or
just ones with parts that cause trouble) the quick
fix is often enough "kill 'em all".
If you want to track down single-cylinder problems
such as bad plug wires, look at the eight Misfire
Current Cylinder PIDs (1-8). If I recall, these need
to exceed some threshold before the current counter
will yip and pass the result to the next layer.
Now, when I had a mis-seated plug wire it was all
over the place obvious - flashing SES, total and
the one cylinder. A scorched wire may still have
insulation integrity enough, even if ugly. That's a
good wire in my book if it holds up to that. But not
to be counted on indefinitely. Point being, the
misfires -could- be not there. If you deliberately
popped one end loose that would sure show if
misfire detection is functional.
functional? On aggressively modded cars (or
just ones with parts that cause trouble) the quick
fix is often enough "kill 'em all".
If you want to track down single-cylinder problems
such as bad plug wires, look at the eight Misfire
Current Cylinder PIDs (1-8). If I recall, these need
to exceed some threshold before the current counter
will yip and pass the result to the next layer.
Now, when I had a mis-seated plug wire it was all
over the place obvious - flashing SES, total and
the one cylinder. A scorched wire may still have
insulation integrity enough, even if ugly. That's a
good wire in my book if it holds up to that. But not
to be counted on indefinitely. Point being, the
misfires -could- be not there. If you deliberately
popped one end loose that would sure show if
misfire detection is functional.
