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Old 03-11-2009, 11:58 PM   #1
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Default 2004 F150 Lariat 49K Misfire cyl 5&6

Hi All,

Had an intermitent jerking around 50 mph, thought it was the tranny, however, as it grew progressively worse it became obvious that its misfiring. Finally got a couple of codes today P0305 & P0306.

Questions.

1. What are the locations for cylinders 5&6?

2. I think these are oppossing, if so what would be the likelyhood that two COP or two plugs went bad at the same time?

3. Could there be a circuit or sensor that these two cylinders share that may be causing the problem?

4. Plugs are suppossed to last 100K, and I keep reading they tend to brake off so I'm a bit apprehensive about swapping them out just to rule them out, is this a likely cause?

5. Could a dying fuel pump or clogged fuel filter be causing this?

6. Any recommendations on a good affordable code reader?

7. On occassion I've noticed the engine starts up almost immediately after I turn the key, much quicker than it ever has, can this be a symptom of a failing injector, and are the 2004, injectors as bad as the 2005 everyone seems to be griping about?

Thanks for your help.

walter
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Old 05-01-2009, 09:19 PM   #2
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5.4 is passenger side front to back 1 2 3 4, driver side front to back 5 6 7 8. I have replaced coils on 5 and 4 already.
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Old 05-02-2009, 01:04 AM   #3
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Since 5 and 6 are up frt
Move coil 5 to 1 and 1 to 5 see if the miss went to 1. if yes then that is a coil gone bad.

you could move 5&6 to 1&2 if the coils are bad then the codes will switch with the coils to cyl 1&2 it's a simple ck. you don't need to pull the plugs.

If the miss fire stays on 5&6
ck plugs, if the plugs look good ... do a compression test.

beyond that ??? computer

Intake leak?

anyone have an Idea?
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Old 05-11-2009, 06:41 PM   #4
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I have an 03 that seems to be doing the same thing. During some accelerating moments (especially in overdrive (automatic)). Sometimes the engine will start running on what seems like 4 cylinders. When I shut it down and start it back up, it's fine. I've read on other forums that the coil packs are the culprits. I've ordered a set off e-bay (global automotive) for $69. When I change them, I'll post back and let you know what happens.
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Old 05-13-2009, 11:25 PM   #5
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Hi all, just wanted to update the thread. Walmart sells a pretty good code reader for $100. My problem turned out to be a bad coil on number 5. I was able to confirm this after reseting the CEL and receiving the same code for misfire on #5. The coil was $25, and its replacement took about ten minutes. All the symptoms I was experiencing disappeared and have had a slight increase in mpg. Thanks to all that contributed to this thread.
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Old 05-13-2009, 11:46 PM   #6
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Bad coils seem like a common problem. I had a few coils go bad on my stang. Not yet on the truck..knock on wood.
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Old 06-12-2009, 12:34 AM   #7
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Sorry this took so long. I replace all eight coils. I bought them off e-bay from Global Automotive. About $85 with shipping to Hawaii. I've had them in for about 4 weeks now and not one time has the truck hesitated, jerked, bucked, or anything else. It accelerates great and is back to normal. It seems that the spring between the plug top and coil gets corroded so that's enough to mess with the spark. I've read other forums where the same thing was done with the same results. Good luck.
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Old 06-12-2009, 12:34 AM
 
 
 
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bucking, codes p0305 p0306, jerking, misfire

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