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2009 Taurus Engine continues to misfire after replacing spark plugs and coil packs

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markiemark
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2009 Taurus Engine continues to misfire after replacing spark plugs and coil packs

Post by markiemark » Tue Oct 31, 2017 5:14 pm

I was driving along last Friday and suddenly my 2009 Ford Taurus begins to shake violently and lose power. After having the car towed in and diagnosed, the shop said three cylinders( 1, 2, and 4) were misfiring and that we would need to replace the spark plugs and coil packs. Now that I have replaced all 6 spark plugs(pre-gapped) and all 6 coil packs, the check engine light is back on and it's running rough again. We used an OBD to read the codes and now it says cylinder 2 is misfiring again. I swapped the cylinder 2 coil pack with the cylinder 5 coil pack and the problem remained in cylinder 2 suggesting its not another faulty coil pack. Auto zone recommended we switch out the knock sensor. Does anyone know what might be causing this cylinder to misfire still? Does anyone know if a bad knock sensor would prevent the cylinder from firing properly and replacing it would fix the problem? If not, what else could be causing my problem? I plan to replace the knock sensor anyway and see if it fixes it. The only other thing i could think of would be a bad PCM. Any help and feedback would be appreciated!


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Re: 2009 Taurus Engine continues to misfire after replacing spark plugs and coil packs

Post by Webmaster » Tue Oct 31, 2017 7:39 pm

Codes never indicate to replace parts, merely where to begin diagnosis. Forget what AutoZone says, they are not experienced technicians, they are parts sellers. I don't think a knock sensor could cause this issue. You'd be more likely to have a P0325 or similar code if it's a knock sensor.

I can tell from what you're saying (e.g. replacing PCM) that you are pretty inexperienced also. PCM replacement is a potential issue for many trouble codes, but it is pretty much always the last resort after many other diagnostic steps have narrowed it down to that.

If I was you, I'd next check for spark on cylinder #2. Pull the plug, put it back in the coil connected, then put the other end of the plug against a metal ground and crank the engine, see if it's actually sparking.

My opinion is that one of two things are at play:
- cheap aftermarket parts were used
- there is a mechanical failure on cylinder #2

There is some good details here @ https://www.obd-codes.com/p0302 - you may even want to ask about your issue on that forum as well.
2000 Ford Taurus SEL (excellent car, sold to a friend)
1992 Mercury Sable GS (good car except for the tranny, sold)
Other Fords owned: 02 F150 SuperCrew 4x4, 11 F150 EcoBoost, 07 Ranger, 01 F150 XLT, 98 F150 XLT, 96 Thunderbird LX, 95 Escort GT, 86 Mustang LX, 82 Mustang

markiemark
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Re: 2009 Taurus Engine continues to misfire after replacing spark plugs and coil packs

Post by markiemark » Tue Oct 31, 2017 8:13 pm

Spot on about being inexperienced. Gotta start learning at some point! As far as cheap aftermarket parts goes, i went with the Bosch Iridium plugs and some Duralast Coils. I should also clarify that the code i got was a P0352. I'll give what you suggested a try and see if the plug sparks or not and go from there. Thanks!

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Re: 2009 Taurus Engine continues to misfire after replacing spark plugs and coil packs

Post by Webmaster » Tue Oct 31, 2017 10:06 pm

Aha so now you see how important it is to post the actual code(s) ;)

See https://www.obd-codes.com/p0352

In light of the new information, don’t worry about spark just yet, focus on the COP wiring, maybe you have a cut or break in the wiring, or it rubbed through against another part. Focus on diagnosing, not replacing parts.

Fords run best with Motorcraft plugs, anything else is rolling the dice. Same goes for coils. Lots of people replace all the coils but I only replace individual ones when they diagnose as failed. They don’t wear out in the same way as plugs.
2000 Ford Taurus SEL (excellent car, sold to a friend)
1992 Mercury Sable GS (good car except for the tranny, sold)
Other Fords owned: 02 F150 SuperCrew 4x4, 11 F150 EcoBoost, 07 Ranger, 01 F150 XLT, 98 F150 XLT, 96 Thunderbird LX, 95 Escort GT, 86 Mustang LX, 82 Mustang

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