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Dave Hopkins
Dave Hopkins, Mercury Technician
Category: Mercury
Satisfied Customers: 1410
Experience:  Fully certified in all phases of automotive repair as recognized by Ford Motor Company.
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2001 Mercury Sable: dohc with a misfire code..single ignition module

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I have a 2001 Mercury Sable 3.0 DOHC with a misfire code on #1 cylinder. I have replaced both the plugs and wires with no success. This engine has a single ignition module for all of the cylinders. The car has 141,000 miles on it and has been well cared for.  One owner.  I have seen this same complaint from numerous owners on different forums without any resolution.  Any Ideas?
Hello and welcome to JA, have you replaced the ignition coil yet? Usually when there is a missfire caused by a wiring concern or the PCM itself, the cylinder that is missfiring will also have the other cylinder that it is paired with on the coil missfiring as well, but when only 1 of the cylinders is missfiring the coil is the likely suspect. My advice is to replace the coil, and please use a coil from the dealer, not a cheapo from the auto parts store, or you will have to replace it again in a week when it shorts out, and also, if you have not done so already, replace the intake seals, they will swell up each time the upper intake manifold is removed, and cause a vacuum leak.
Customer: replied 6 years ago.
Just to clarify: It seems like a coil problem would cause issues on all of the cylinders. I know it is an electronic system, however. Is there any way to test the coil. I imagine that it is a rather expensive component.

Thanks for the heads up on the manifold seals. They are only about a year old. Should I still replace them?

Thanks for your help.
the coil is driven by the PCM to fire 2 cylinders at once, they are paired up, so when cylinder #1 fires, so does #5, #2 fires along with #6, and #3 and #4 go at the same time, so since you only have a missfire in #1, we can rule out the wiring and the PCM as a problem, the coil is a very common concern on this engine, if the seals are only a year old, then leave them, but if you get a lean code after coil replacement, then the seals need replacing again, testing for the ignition coil, unless you have a scan tool that can read spark duration, then just replace it, trust me.
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Customer: replied 6 years ago.
Customer: replied 6 years ago.
Dave, I changed out the coil in no time and the car is running great. Thanks again for your assistance!

Dave Tostenson
glad I was able to help you.