2006 Ford Taurus Multiple Misfire

06 Ford Taurus, 225k miles. Was driving home yesterday and car began sputtering when I slowed, would slowly ramp up RPM and speed after stops. Found drips around the fuel filter, so I changed it this morning. Now getting misfire codes (P0300, P0304, P0305, P0306). Checked the plugs, cleaned, and gapped them. Still running rough. Would allowing it to run and having the computer reset be a solution? What else can I try?

Once you solve the misfires. The check engine light will go off. Multiple misfire usually starts with fuel. Check your fuel pressure with a fuel pressure gage. With key on and engine off you should have 30-55 lbs. With engine running 26-45. Turn the key off pressure should drop very slowly.

Check for a worn timing chain.



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my misfiring taurus had .100 plug gap. maybe that had a bit too do with it. been told. never put a used plug back in. why bother with used

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Did you do anything with the spark plug wires ?
The only thing I can think of that would cause just the front 3 cylinders to misfire, is they’re wired wrong.

Notice on the coil pack the back 3 are in order 1,2,3
Notice on the coil pack the front 3 are NOT in order 5,6,4
It gets wired wrong all the time.


P0300 is a random misfire, and the p0304/5/6 are for misefires detected in those specific cylinders. So that’s a big clue, something’s amiss in that bank of cylinder’s that isn’t amiss (or not as much) in the other bank. The coil pack idea is well-discussed above, definitely a possibility.

“Misfire” means the computer failed to detect the crankshaft accelerating (rotationally) after it fired a specific spark plug. The common causes for that are

  • Coil pack failure results in no spark to spark plug
  • Spark plug faulty (seems unlikely all three would be faulty, but worth pulling them and looking)
  • Ignition module failure (an electronic gadget in-between the computer’s firing signal and the coil)
  • Problem with the air/fuel ratio in the cylinder, not enough fuel or not enough air
  • Coolant leaking into the cylinder (faulty intake manifold gasket for example on some configurations, faulty head gasket on others)
  • Low cylinder compression (piston rings, valves, timing chain etc)
  • Faulty crank position sensor

lol … you think… lol … ? If the gap on myCorolla starts to get too wide the first symptom is I hear some minor engine pinging on uphills. OP, have you been hearing any engine pinging of late?

Thanks for input everyone! In the end, I took the car to a garage and found compression issue - lost a cylinder. Needs a valve job. When asked if something I did, they said, yeah you drove 225,000 miles!
The rest of the car is in good shape - might just go to a pick and pull and replace the engine for $115.
Thanks again - always good info from this site!


Good luck. Please let us know how it turns out.

and how are you going to make sure the engine from pick a part is in better shape than yours . . . ?

I think installing a used engine from PNP is worth a try. Try to find a car that looks like it was wrecked, hit from behind or on the side behind the engine compartment if possible. Any used engine is a risk of course. The way you’d know it’s in better shape than the one it replaced is it runs better. If it runs worse then it was a risk than didn’t pan out.

Hi everyone - ended up junking the Taurus. The age, mileage, and what-ifs weighed too much, so I got a more reliable new (to me) car. I’m sure I’ll be posting new questions regarding the new car as well as my others. Thanks as always to this group!