5.4 randomly misfiring
 

Hey guys, great looking forum you have here. I have a 2005 5.4 F-150 I am working on for a customer and am looking for a second opinion as to what the problem with it might be. First off it came to me on a rollback because the owner tried to replace his plugs after he noticed it missing and of course broke one off. So after I extracted the plug from #8 cylinder and installed a new plug I cranked the truck and it was idling very rough and had a terrible miss around 1200rpm. I pulled the codes and got several misfire codes and ignition coil faults on #5,6 and 7 cylinder. Popped in 3 known good coils in these 3 cylinders with no difference. On Mode 6 on my diagnostic software you could watch the misfire count steadily increase on #7 and every now and then there would be a single misfire on #5 and 6. It also had several codes for O2 sensors biased, stuck rich on that bank. Well since it had a brand new plug and coil, I popped an injector in #7 and havent had a single misfire on it since and it also started idling alot better and all the O2 codes went away. The problem I am having now is #5, 6 and now 8 will randomly misfire, sometimes build up a steady count on one of them, sometimes just skip around between them. The truck has brand new plugs in all 8 and new coils on this bank also. The truck has 115,000 on it and does have some cam phaser noise on the bank causing the problem, but its not too terribly bad, I have heard alot worse. My problem is something on that bank only as the passenger side bank is fine. I am wanting to say cam phaser now since this is the side with the noise. I have changed them before but have just experienced the noise, never one running like this because of it. Possibly jumped time a little? Has anyone seen this? Any ideas would be appreciated. Sorry for the extremely long post.

What kind of plugs did you use in the truck? These trucks seem to fight with everything except Motorcraft plugs. Also when installing the new ones don't forget the anti-seize on the plug ends.

I really don't think the cam phasers are causing the idle problem you are having. I haven't read about them doing that before so would start to look else where first.

What else has been done to the truck recently? Fuel filter, throttle body, and etc...

He replaced 7 of them with Motorcrafts and broke the last one he had left and thats when it was brought to me and I extracted the plug and replaced it with the Motorcraft he had left. He is an elderly man and said he has never had any trouble out of the truck until he noticing it missing and he figured it needed a set of plugs, and so the story goes from there.

Also I see a pretty good bit of these trucks and do the typical injectors and coils and alot of the cam phasers before the local Ford dealers started taking care of them. Also i go around to alot of shops and peoples houses extracting plugs so I pretty familiar with these I have just never seen one act like this.

what about the VCT solenoid

If it makes you feel better, I just changed my plugs also. Right off the the back I had cyl4 misfire. Turns out I got a bad plug. The first thing I would do is replace the new plugs with some newer ones and go from there. Swap the coils, put the ones that are on the bank that's misfiring and put them on the other side of the motor. If you just go changing a bunch of things you may as well just be throwing away money. 4 new plugs only set me back 38 dollars and I only needed the one. But well worth the investment.

Make sure he used the correct Motorcraft plugs. I had a similar problem on an Expedition 2006 5.4L 3V. The wrong motorcraft plugs were used. Replaced using the correct SP507 plug and misfiring stopped.

I had my 2006 F150 5.4 put on the scanner P0018 the computer indicated that Bank 2 had a cam problem .. idling ruff and mech said it was out ot of timing on that side.. any advise out there..

2007 5.4 misfire
 

I've been reading all the posts I can about this problem and have noticed that no one has a definite answer to this problem. Plugs, coils, boots, head leaks etc. and the problem still seems to come back with everyone.
I really appreciate all the posts but is there one answer to this very common problem to fix it. We all have the same symptoms and there has to be one answer to this.
Please help, just totally frustrated!

The most common cause of misfires is worn spark plugs. When the plugs are worn the gap is wider so it takes more voltage to jump the gap. The coil can only put out so much so if the required voltage is greater than what the coil can produce then it doesn't fire. Sometimes the voltage finds it's way outside the plug between the plug and boot and the spark goes outside the plug to ground. This causes carbon to form where the spark passed and the carbon acts like a conductor so now there are 2 paths for the spark, through and around the plug. Electricity take the path of least resistance so when you are cruising in overdrive at 45 mph then the PCM leans the mixture and advances the timing for best fuel economy but what that does is makes it harder for the spark to go where it needs to so it goes outside the plug and boom, misfire.

If there is any leakage of spark, it can be identified easily by the carbon tracking down the plug, I had a cam phaser fail and gave me random misfire codes only, be careful you have noise on that bank and thats not a good thing. Dave

I'm ready to scream about this problem! I live in a smaller town (16,000) and know 5 other guys with very similar problems with the same truck. Terrible misfiring going on, and has for years. I have a '06 and have replaced the plugs 4 times now, with coil packs here and there. Tonight we're going to replace all of the coil packs in hopes that changes it. Should we hit new plugs, boots, and injectors as well just in case? I don't want to keep throwing away money.

For those that aren't aware of the problem, aside from the rough idle when going 55 mph on the highway, around 1200 rpm going up a slight incline, or hill..it starts chugging bad. Shutting overdrive off, and kicking down helps, but is terrible on the fuel economy. At one point it plugged my left cat, so I had a guy cut the cats off, burn the crap out, and put them back on. Will be getting new cats now, as it sounds like crap.

Either way, this was supposed to be my "buy it new, own it forever" truck, and if I can't get this problem fixed this summer I'm dumping it.

Also, has Ford corrected this in their 08-09 trucks? Reason I ask is I have a brand new topper, and it will fit those years. So effing sick of this recurring problem!! Any help is appreciated. I know there's a ton of us out there with this problem, and if I call my local Ford garage they play dumb like it's news to them. Yeah right.

Thanks in advance!

thoughts
 

I am having the same problem. When I connect my code reader and clear the codes it seems to correct. This indicates to me it's electronic. Going to do some more research. I have a K and N air filter. Will clean that first and will check fuel filter

Nope, the Misfire issue is still present in my 2008 F250 with the 5.4l 3-valve. It just started at 162k miles., but I had bought the truck used 2k miles ago. It ran like new for 2k miles I owned it, then I noticed a slight stumble (cyl missing) while slowly pulling out from a stop sign. It cleared up as soon as the engine got to 1500-2000rpm. But it set a code. P0304 - CYL 4 MISFIRE.
I'm gonna try swapping coil packs to see if misfire moves. If the misfire does not move, I'll test the injector before attempting pulling the plugs. I gotta be ready and borrow an extractor before I try that. :-arrgh

@David7.3 I agree that close inspection of misfiring plugs can reveal carbon tracking down the ceramic (if the arching over is occurring above the threads). But, your handle prompted me to take a look-see at your profile. Aren't you on the wrong forum here?