Misfire


#1

01 Taurus, 3.0 pushrod motor. Single 6 pack style coil. I replaced worn plugs 2 months ago for misfire. Car seemed to run fine. Now, I have misfire again. Code is for single cyl, 0303. Would u expect plug to foul, or bad wire, or possibly bad coil? I don’t know how these ford coil packs fail. Can u lose 1 or more spark outputs with them?


#2

It could be a bad wire too. With a car 13 years old, the wares could be at the end of their life.

Also a coil pack can just lose just one output.

You should pull # 3 plug and seee if it’s fouled.
When you replaced the plugs two months ago…did you have a #3 misfire then too???

Yosemite


#3

I never checked codes earlier. I pulled plugs first. All had huge gaps. Plug 3 is spotless. Not even dirty


#4

new coil pack fixed misfire. i also am getting a alternator light that comes on/off. man, you touch anything on this car and it freaks out. alternator is fairly new. maybe prior owner has warranty? he is in my circle of friends.


#5

@Cavell‌

I would check compression if I were you

We have a bunch of Tauruses with the Vulcan motor in our fleet, and quite a few have had misfires due to low compression

In several instances, the problem was top end. The engines needed a valve job

Correct me if I’m wrong . . . the coil pack from a few months ago only temporarily fixed the misfire


#6

You can check your wires with an ohmeter. My guess is #3 will test as wide open or infinity. If it’s over 20K ohms, replace it. I bought mine from Radio shack a few years ago, on sale for $9.95.

#3 is on the back side of the engine, nearest the steering column, so it’s a little harder to get to. All you need to access are the ends to test it. The back three wires are housed in a trough that carries them under the intake manifold.


#7

Take it to autozone or advance and get the charging system checked. Make sure battery connections are clean.


#8

I did try a new plug wire. That did not fix the miss. Prior to today, I was using the original coil pack. Now I have a new one and engine runs fine. Could be as simple as alt connector having poor contact. I did have the alt out to fix the timing cover gasket


#9

Since I’m a firm believer in pattern failures, I’m leaning towards top end problem as the cause for #3 misfire


#10

Why did the flashing CEL go away with new coil? If low compression is issue?


#11

Here’s my take: 2 months ago you developed a misfire on #3. You replaced the plugs. The old ones had huge gaps. The misfire went away. Your coil pac was probably on it’s way out but was now able to fire across the proper gap. The misfire returned due to a further deteriorating coil pac. You replaced the coil pac a couple days ago and the miss went away. Seems like you’re there - almost. I would replace the ignition wires as Yosemite suggested. They’re 13 years and the misfire may eventually return - the wires being the weak link.

As far as the alternator goes I would check the connections since you had it out for other work.


#12

@Cavell‌

All I know is that we had several Tauruses in our fleet that had misfires due to low compression

If nothing else, check the compression to rule it out as a possible cause

Your problem may very well be due to the wires, but checking compression would give you peace of mind