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P0302 — Cylinder 2 misfire — where to go from here.• Duratec

Bob Blaylock

Bob Blaylock

CEG'er
Joined
Apr 24, 2001
Messages
135
Location
N38°35' W121°29'
The car in question is a 1997 Ford Contour, “Sport”, with the, 2.5-litre V6, an an automatic transmission.

It was running just fine last night, but today, as I tried to go to work, it was running quite rough, and the Check Engine light was flashing at some points.

I've pulled the code P0302, indicating a misfire on cylinder 2.

I think I have determined that the number two cylinder is the middle one on the rearmost bank—is this correct?

And where should I go from here as far as diagnosing the problem? I can think of any number of reasons for one cylinder to be misfiring. If it were a front cylinder, I'd try pulling and inspecting the spark plug and the plug wire and inspecting them first, but as this looks to be one of the more difficult cylinders to access, I thought I'd ask if there's an easier way to diagnose the problem before I try pulling out any parts.
 
I started have symptoms like that on my 98 and it was the coil pack starting to fail.

Its not that hard to reach behind the manifold and remove the plug wire. At that point you can stick a different plug in it and see if it is sparking. Another thing to do is start the car in the dark and see if you can see sparks jumping from the wire to ground, could just be a bad plug wire
 
I had that very same problem code TWICE on my SVT. You are correct, it is the middle cylinder in the rear bank. Both times it was the plug wire. I guarantee you that's what it is! The last one was only 15k miles old, and still failed. And all of the plug wires were Motorcraft. Not sure why that particular wire seems to be prone to failure, maybe heat has something do do with it ...

Give it a shot, I am sure that's your problem too.
 
I replaced all the spark plugs, and the wires, and no change. It still runs rough, and the OBD-2 code P0302 still occurs, telling me that I'm getting misfires on cylinder 2.

The attached file SCAN11.ZIP contains the data recorded from this car on a test drive after I finished putting it back together with the new plugs and wires. You can play it back using the software available at <http://www.obd-2.com/>.

I suppose, at this point, it's most likely either a fuel injector or the coil pack. Is there any way to diagnose it from here, short of just throwing parts at it?

What other causes could there be? It seems clear to me that the problem is specific to cylinder 2. Plugs and wires seemed to the most obvious possible cause, but that wasn't it.

If it's the coil pack, it looks like that's easy to replace. I pulled and reinstalled it to get at the back plugs, so replacing it entirely would be less work that what I already have done today.

If it's a fuel injector, how bad is that to replace?
 

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Well, unless advice to the contrary comes our way before then, my wife plans to stop by AutoZone tomorrow and get a new coil pack, which hopefully I will be able to motivate myself to install after work tomorrow night. I guess, if we're taking the “throw parts at it” approach to trying to fix this problem, the coil pack is the most logical next part to try.
 
Try disconnecting the spark plug wire for cyl 2 from the coil pack and holding it just a little away for the coil pack, crank the car and see if there is a consistent spark jumping from the coil pack to the wire. If not, new coil pack, if yes maybe next step would be injector. For that remove UIM crank car and check if cyl 2 injector is squirting fuel
 
The reason your not getting much action in this thread is because there are a million other threads with the same problem, and people get tired of covering the same topic over and over again.

coil pack

Make sure you used double platinum plugs.
 
One way to determine if the trouble is the coil pack (or injector) is to swap the plug wires (both ends) for #2 with cylinder #3. If the trouble follows to #3, coil. If the trouble stays at cylinder #2, plug or injector seems suspect. Try a tank injector cleaner, but not the $0.99 stuff.

FWIW, Autozone's Duralast coil pack is $66 plus tax. I'd go with a good used MOTORCRAFT from local recyclers myself.
 
It was the coil pack. I just installed the new coil pack, and now my car is running very smoothly.

All the cars I've had, over all the years I've had cars, I have never before had an ignition coil fail on me. I get the impression, however, that this is not a terribly uncommon failure with these cars. There must be something about these more modern coil packs that makes them more failure-prone than the more primitive counterparts in more primitive cars that I have owned.
 
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Glad you fixed it. My experience has been dirt on the plug insulator and boot and worn out plugs (wide gaps) cause it, and does tend to be #2! Happened recently on my sister's car. I fully expect to replace a coil pack next time. My old Dodge had oil leak out of the coil, and it was still working OK, my neighbor had multiple single cylinder coil packs fail on a Lincoln LS.
 
This old thread isn't dead! My Mystique has still has #2 Misfire, new coil, plugs, wires. Must be the injector, car intermittently starts very rough. Anybody ever replace injectors to fix P0302?
 
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