Is there any way to check coil packs on a 2000 Ford Crown Vic? I have a
mis fire on a cylinder (or maybe two) and if the pack is good I may
just need a new boot, (if they sell only the boot) I did have the same
problem a year ago and the dealer replaced two packs under warranty,
now Ford wants some big $$$ to check out the car and about $250 per
coil pack. At these prices I should replace all remaining 6 at $80
each. Any Ideas??? What is the best way to find out which coil pack is
giving me the problem, the check engine light is not on.
Did you scan it for trouble codes? The older OBD I Fords would do a cylinder
balance test with nothing but a jumper. You could try to find a service
manual at the public library. This adds nothing to your solution, but my
girlfriend's Cavalier set a code that said # 4 cylinder was misfiring.
Turned out to be a bad boot on the plug wire. It too has distributor-less
ignition. When fixing it I found some real auto parts stores sell individual
wires. You may find the stuff you need at a NAPA store.
I don't believe that Ford's EECV has a built-in cylinder balance test. At
least not one that a shade-tree-mechanic type scanner would initiate. Seems
that Ford decided to make this a money maker for its dealers. On the other
hand, it may not be required as much as before. If there is a persistent
misfire, there will be a stored code identifying the misfiring cylinder.
This is done on-the-fly without killing ignition, by a rather sophisticated
algorithm that measures the angular acceleration profile around the
And by the way, the OP's car seems to be coil-on-plug. No ignition wires in
cylinder balance test with nothing but a jumper. You could try to find a
but my girlfriend's Cavalier set a code that said # 4 cylinder was
distributor-less ignition. When fixing it I found some real auto parts
stores sell > individual wires. You may find the stuff you need at a NAPA
Actually for Ford 4.6L COP engines the coil pack boot is effective a short
plug wire. The actual coils are above the intake manifold. The boots connect
the coil packs to the plugs and can (and do) go bad, just like longer plug
wires. I recommend replacing the boots whenever you change the plugs. The
boots cost $3 to $5 depending on where you shop. If you replace the plugs
every 75,000 to 100,000 miles, the extra $24 to $40 for the boots is good
here is a neat trick .... if you have a supsect coil pack and you want
to perform a HOMMADE cylinder balamce test this is for you.
First make sure all you wires are good
note this works best at the coil/cap end but if plug wires are good you
can do it at either end.
now take some vacuum line (about one inch or so .. just enough so you
can see it out the bottom of the boot.)and fit it in the plug wire.
plug the other end into the coil or distributer cap or whatever you
have. Repeat for all wires.
make sure you have no problems or at least no more than you did before
now take a test light and ground the end lile normal... you can use the
sharp end to touch the vacuum hose to "safely short" that cylinders
spark to ground killing that cylinder...
presto poor mans cylinder balance test you should be able to pinpoint
the missing cylinder now..
----- Original Message -----
Sent: Monday, July 11, 2005 8:49 PM
Subject: TROUBLESHOOTING FORD COIL PACKS
If the check engine light is not on, why do you think you have a misfire? It
has been my experience that the OBDII system is very good at detecting
misfires. Ford Issued a TSB warning dealers that 50% of the coil pack being
replaced under warranty were not bad. The TSB included elaborate tests for
determining whether or not a coil pack is bad. The tests don't look like
something you can do at home. If you have a misfire, the OBDII code will
identify the cylinder with the misfire. The boots are separately replaceable
(they cost $3 to $5). The dealer should sell you a coil pack (uninstalled)
for around $100. Aftermarket coil packs are available for less than $75.
Lazy mechanics often blame coil packs when they are not at fault. Dishonest
mechanics often blame the coil packs because they are profitable to replace.
Are you sure you don't have an intake manifold leak or other problem?
Here is part of the Ford TSB:
Approximately 50% of coil on plug (COP) coils returned for warranty do not
have a problem.
The misfiring cylinder must be identified through Self-Test misfire codes or
through WDS Power Balance. Rule out base engine problems, rule out fuel
problems, and then look at ignition problems (be sure to rule out coil
primary circuit issues). Once the above steps have been completed, and the
issue is in the secondary part of the ignition system, the oscilloscope
procedure outlined in this TSB can isolate the difference between a coil or
spark plug problem.
The optional WDS COP Kit available through Rotunda will provide more
accurate diagnosis and help reduce replacement of non-defective parts. The
Kit (418-FS528) can be purchased through 1-800-ROTUNDA.
The following material will detail the diagnostic steps on WDS to take the
guesswork out of misfire diagnosis using the COP Kit. The following
procedure is for cylinder specific misfires and not random misfires. Random
misfires have a different root cause and are not covered by this TSB.
A misfiring cylinder is lacking power relative to the other cylinders. The
causes for a cylinder specific misfire could be fuel, spark, or mechanical
problems. Perform a thorough visual inspection. If no visible concerns are
found use the following WDS tools for misfire diagnosis:
^Self-test (Check for codes first)
^Power Balance (Identify the cylinder of concern)
^Relative Compression (Rule out a possible mechanical issue)
^Fuel (Make sure fuel injectors are not restricted)
^Ignition (Make sure spark plugs and coils are working properly)
Oscilloscope (Detailed signal analysis)
NOTE USE THE ENCYCLOPEDIA BUTTON IN THE LOWER LEFT CORNER OF THE SCREEN FOR
DETAILED INFORMATION ON THE WDS TOOL BEING DISPLAYED.
If there is a self-test code identifying a particular cylinder then you just
need to determine if it is a fuel, ignition, or possibly a mechanical
problem. Proceed to Step 2 after running Relative Compression to rule out
any mechanical issues. If there is no self-test code and the customer
concern is a miss, proceed to Step 1.......
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