code P0300 Random Misfire backfiring, cutting out

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Old Feb 6, 2010 | 10:53 AM
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code P0300 Random Misfire backfiring, cutting out

So among the other list of problems ive dealt with this past winter, heres another. Cuts out like CRAZY, backfires and has crap for power. It jerks and chugs, the whole shabang. This is where it gets confusing. I have a 2002 5.4 running off of my 99 4.6s coil PACKS, 2 of em. They, unlike the motor and everything else ive already replaced, has 330,000 miles on them, yep they are origional.

I did do a search, and i read that it may be a lean code? As far as fuel injectors, BUT im not getting a specific cylinder misfire code, and my SES light is not flashing (misfire). As far as i know , coil backs just go out, but i would be throwing 4 misfires wouldnt i? Is there any such case that it may just be going out, 1 cylinder at a time? I am stranded now, with no way to work so, anything you guys gotta say will be much appreciated as usual
 
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Old Feb 6, 2010 | 11:19 AM
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Coils/coil packs don't always just stop working they get weak causing intermitten ignition as well. Why not pick a set up and replace the old ones. You sure got your moneys worth out of the old ones. While your at it, now that your sparkplugs are gas soaked and fouled I'd change them as well in fact I'd change them first. Motorcraft please. Take care.
 

Last edited by DYNOTECH; Feb 6, 2010 at 11:24 AM.
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Old Feb 6, 2010 | 04:04 PM
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Yea, sounds like the packs FRod. I might check the fuel pressure first to be sure the pumps alright/ no delivery problems. You CAN check compression, but you should be good there, you just got it back together right.

I bet its the packs as well.

Are you running cats ?
 

Last edited by jbrew; Feb 6, 2010 at 04:07 PM.
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Old Feb 6, 2010 | 04:48 PM
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Coil packs can develop carbon tracks and cracks, which will cause all kinds of misfiring and crossfiring. I'd probably replace the plugs, wires, and coil packs with OEM Motorcraft.
 
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Old Feb 6, 2010 | 11:10 PM
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Thats what i was hoping you would say. Ya just got her back together , running just cats. The spark plugs have maybe 200 miles on them, and they were very expensive so ill have to see if they are still good. Also the wires have like 4,000 miles and are 9mm ford racing wires so those are good. I got the coilpacks ordered, will be in store tomorrow so i guess wish me luck haha!
 
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Old Feb 6, 2010 | 11:19 PM
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What kind of plugs? You ordered MSD's?
 
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Old Feb 7, 2010 | 06:13 PM
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Ya i realized i still have that in my description, no they were origional. Last summer i ordered MSD coil packs and must of ordered COPs instead, so i sent them back and realized the misfire was a bad wire and never got the right ones. I got new coil packs and denso t16's. Still getting the random missfire P0300 on my edge too.
 
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Old Feb 7, 2010 | 06:22 PM
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Sounds like bad compression/ -valves are gone.
 
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Old Feb 8, 2010 | 08:11 AM
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how could that be though, the heads were rebuilt and ported and installed with comp cams and Trickflow oversized steal valves.
 
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Old Feb 8, 2010 | 09:14 AM
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Not sure, haven't you checked everything else? New Coils/ wires are good/ plugs are good. Maybe something fell apart in the heads ? Rocker/Follower problems ? Are you getting enough fuel ? Are you tuned ? Is you wire harness resting on top of the AC Accumulator ? You know what to check out right ? Have you gone thru it? Make sure the cats aren't fusing the cells together, which will eventually reduce the flow needed.

I guess if you've gone thru it, it wouldn't hurt to compression test. - Did you try re-booting or running another tune ? Can you run the stock tune with those heads?
 
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Old Feb 8, 2010 | 11:44 AM
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I guess i did not quite to my part. As i was checking for intake leaks with carb cleaner i heard this faintt "tickticktickticktick" and not a motor tick, the sound of a spark plug wire cut open grounding off the alternator. The wires were not correctly fastened and were resting on top of my alternator pully, cut it open. I have not swapped new wires yet but i PRAYYY this is whats causing "random missfires". Yes i had it on trans tune, put it back to stock, now it says my edge is out of date and i cant customize or load other tunes, dunno how to fix that. Compression test came to 190 on the NUTS on every single cylinder. The heads were professionally built by TNT Racing so i trust their work. There non canned tune yet, been low on money but it ran fine the last 2,000 miles if drivin it since i got her back together. Fuel pressure reg, pump and injectors tested OK. What were you saying about the harness resting on top of the AC Accumlator? All my AC components have been removed.
 

Last edited by FRod; Feb 8, 2010 at 11:47 AM.
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Old Feb 8, 2010 | 12:46 PM
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So i found an old set of stock wires brand new never used, and i swapped 1 out. The stock ones are 7mm and the ones i have on there are 9mm, that shouldnt cause any problems should it? Because it seems like it may got a little worse, or did nothing.
 
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Old Feb 8, 2010 | 01:17 PM
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Sounds like you know your stuff here so I hate to even ask this but are you sure that you have the plug wire for each sparkplug attached to the correct coil pack terminals. It's easy on these coil packs to make the wrong connection from pack terminal to the correct sparkplug. I know the coil packs have a sticker on them identifying two cyls per terminal and I think you are familier with the 4.6 cyl locations. No disrespect intended here but its easy to get these wires hooked up to the wrong cyl sometimes. This would give you the problems you are having with randon firing. Take care.
 

Last edited by DYNOTECH; Feb 8, 2010 at 01:25 PM.
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Old Feb 8, 2010 | 01:31 PM
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Also, - Could you have jumped a tooth (timing)? I know you just did it, so it shouldn't unless something came undone. I know they can backfire when missing, - but they most definitely do when out of time. Iduno, - long shot lol.
 

Last edited by jbrew; Feb 8, 2010 at 01:34 PM.
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Old Feb 8, 2010 | 02:01 PM
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I hope not! But i highly doubt it with how tight the brand new chains were which made it a pain, and i double triple checked the timing before i put everything back together. Its a missfire coming from somewhere. Taking out all the plugs to look at em and see if maybe i shot a plug but im doubting that too.
 
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