# 5.4 running rough



## porabjr (Nov 21, 2012)

Just yesterday truck started running rough. Seems like slight misfire but no check engine light. Idles ok, but rough at all other speeds. Truck has about 150K on it. Bought it this past April and repair history is not really known. Given engine history with spark plugs I am a little reluctant to even pull one out. Any suggestions?


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## unhcp (Jan 20, 2010)

Spark plugs should be changed if they have never have been, but more likely it is a bad Coil somewhere, those coil on plugs have problems. I have 3 fords and always had to change them at some point.


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## Wilnip (Oct 4, 2011)

Put a scan tool on it. It should say "cylinder 3 misfire" or something like that. Then change that coil. I'm sure that will clear it up. Check engine light does not have to be on to denote a misfire.


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## Whiffyspark (Dec 23, 2009)

porabjr;1653650 said:


> Just yesterday truck started running rough. Seems like slight misfire but no check engine light. Idles ok, but rough at all other speeds. Truck has about 150K on it. Bought it this past April and repair history is not really known. Given engine history with spark plugs I am a little reluctant to even pull one out. Any suggestions?


What year?


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## porabjr (Nov 21, 2012)

its an 03, will hook scan tool up and see if I can get more info that way. thanks for suggestions guys.


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## Whiffyspark (Dec 23, 2009)

porabjr;1653696 said:


> its an 03, will hook scan tool up and see if I can get more info that way. thanks for suggestions guys.


Even if you break the plugs its not a big deal


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## seville009 (Sep 9, 2002)

porabjr;1653650 said:


> Just yesterday truck started running rough. Seems like slight misfire but no check engine light. Idles ok, but rough at all other speeds. Truck has about 150K on it. Bought it this past April and repair history is not really known. Given engine history with spark plugs I am a little reluctant to even pull one out. Any suggestions?


My 2006 f350 5.4l was running real rough starting from a dead stop, and sometimes cruising at highway speeds. Has abour 58,000 miles on it. Dealer said it was the cat converter being plugged up, so he changed it out. Didn't fix it. They then ran the scanner on it, and said it was the #8 coil, so they changed it. That fixed prob 95% of the problem. In the end, they changed all if the spark plugs, and it runs great now.

About three years ago, it had been running rough, and the mechanic I was using told me it was ethanol causing the problem. I used ethanol cleaner in the gas for about a month, and it cleared the problem up until recently when all new plugs were put in.


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## Antlerart06 (Feb 28, 2011)

Get you a code reader that has live feed 
Show which ones that are not firing right

Mine ran rough when truck was sitting out side in rain Come find out was a small crack in a coil and code reader found the problem


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## wizardsr (Aug 8, 2006)

seville009;1653758 said:


> My 2006 f350 5.4l was running real rough starting from a dead stop, and sometimes cruising at highway speeds. Has abour 58,000 miles on it. Dealer said it was the cat converter being plugged up, so he changed it out. Didn't fix it. They then ran the scanner on it, and said it was the #8 coil, so they changed it. That fixed prob 95% of the problem. In the end, they changed all if the spark plugs, and it runs great now.
> 
> About three years ago, it had been running rough, and the mechanic I was using told me it was ethanol causing the problem. I used ethanol cleaner in the gas for about a month, and it cleared the problem up until recently when all new plugs were put in.


He has an 03, very different from your 06.

Coils are probably the culprit, very common. Gotta have a scanner to figure out which one. Also, if the boots are at all dry, replace them and be sure to use dielectric grease. Those things drive me crazy, luckily they're cheap enough... Don't worry about the plugs, they fixed the stripping issue in 2002, and the ones that break are the 05 and up. In terms of spark plugs 2002-2004 were the best years for Ford 5.4 and 6.8 gassers.


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## porabjr (Nov 21, 2012)

Will get my hands on a scan tool this weekend. Hopefully it's not the 4 or 8 cylinders since I can't even see the damm things. Anyone have a suggestion on a brand of coil if that is the culprit. Did a quick search and saw prices all over on internet from $67 for some Chinese brand on Amazon that got great reviews to $400 from Ford. Seems like quite the range


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## Antlerart06 (Feb 28, 2011)

porabjr;1654065 said:


> Will get my hands on a scan tool this weekend. Hopefully it's not the 4 or 8 cylinders since I can't even see the damm things. Anyone have a suggestion on a brand of coil if that is the culprit. Did a quick search and saw prices all over on internet from $67 for some Chinese brand on Amazon that got great reviews to $400 from Ford. Seems like quite the range


I paid 58 from a NAPA store Im thinking I would have look tomorrow at the shop where the tickets are


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## theguynextdoor (Sep 18, 2007)

I had the same problem on my 2000 f250 5.4L. The truck hesitated while accelerating and ran rough. Turned out it was a couple bad coils. After those were replaced, the others kept going one or two at a time. Within 2 months they had all been replaced. The coils crack and get moisture in them. The problem was especially bad after the truck was out in the rain.


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## porabjr (Nov 21, 2012)

put code reader on it this weekend and sure enough P0304. Just my luck that it is cylinder 4. Waiting for coil to replace before it gets too cold. thanks for help guys. will let you know if that resolves the problem.


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## Antlerart06 (Feb 28, 2011)

Well its 4 when you get to it check the others out on that side look real close if any has a crack in it they will go bad


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## porabjr (Nov 21, 2012)

Changed out the coil today and seemed to have fixed the problem. Running smooth now and and no misfire detected. Worst part was reaching back to that #4 cylinder (and in typical fashion dropping the bolt back there). Thanks for the help out there.


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