Motor Age Garage: Triple Play - A simple running complaint turns up more than one culprit, and a few more on the way. - Search Auto Parts | Automotive News
Figure 5 Here are the Ford Mode $06 test results. This is a catalyst damaging misfire counter showing percentage of misfires
and maximum limit for cylinder Number 1.
Mode $06 lists the individual test results that make up the non-continuous system monitors; CAN systems also include test
results for continuous monitors. These tests are identified generically by a hexadecimal number that some newer scan tools
automatically translate into English. Ford is kind enough to already list a misfire counter of sorts in pre-CAN models and
is probably the most commonly used Mode $06 feature. It is identified as TID $53. Each TID also has a Component ID (CID),
and the component IDs with this test correspond to the individual cylinders. The CID in Figure 5 shows test results for cylinder
Number 1.
Specifically, this is the test result for the cylinder identified while monitoring for catalyst-damaging misfires. The test
numbers do not reflect the actual number of misfires; these have to be converted to a percentage by multiplying by 0.000015.
The result represents the percentage of misfires counted during the test cycle, and the maximum percentage for that given
rpm and load that would have resulted in a catalyst damaging misfire. If the maximum percentage is exceeded, the MIL flashes
and a code is set.
Figure 6 Scope shot of ignition secondary with new plugs. A scope shot of the ignition secondary after new plugs were installed
shows how a plug gap change of 0.015 made a drastic change in firing kilovolts (Kv).
Even though this test "passed," you can see that there have been misfires in this cylinder, and the other cylinders I checked
also showed some counts as well. Like the MAF results, the problem wasn't yet severe enough for the ECM to set a code, but
there was reason to suspect that it was certainly coming and also helped strengthen my belief that the worn plugs were the
cause of the stumble.
I went back to the customer to inform him and my service writer what I'd found. I recommended new plugs and an EGR valve.
I also told him what I'd found with the MAF sensor and told him that, while it wasn't causing his MIL to come on right now,
I believed it would soon.
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The customer approved the repairs, and after the plugs were installed, I rechecked the secondary pattern and got one similar
to that shown in Figure 6. Another test drive with my customer a few hours later, and he was ready to take his family on the
road with peace of mind.
PETE MEIER is an ASE CMAT, a member of iATN, and a full-time tech with CarMax in Tampa, FL. He started doing oil changes and minor repairs
more than 30 years ago and brings a variety of experience to bear. His current job involves all manufacturers' lines, and,
as Pete says, "provides me constant opportunity to learn something new." Diagnosing electrical and driveability problems are
his favorite challenges.
Peter Meier is an ASE-certified Master Technician, member of iATN and full-time tech in Tampa, Fla. His experience reaches back over 30 years, and his contributions to Motor Age reflect a wide variety of experience with almost every make and model.
Articles by Peter F. Meier
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