wad_96

Okay people, I've always been able to read other postings to get any information I needed, but now I'm going to tell this scenario myself, because it's odd. I have a 2004 FX4 SuperCab (5.4L Triton) with 148xxx miles. On a trip to Missouri, the infamous misfire started where the engine would chug under load at low RPM, then kick out of O/D, giving that sensation of a transmission issue. On the way back home, the problem became more frequent to the point I came to the realization that it had to be a misfire. As you all know, you have to nearly jolt the snot out of the engine to get the computer to register a misfire code. I never could get the misfire frequent enough to register, so I decided to clean all 8 COP's and boots and see if it went away. The plugs were changed with new motorcrafts about 20k miles back so I have my doubts that they were the problem. The coils on the other hand, I think are factory, so they've lived a long life. After cleaning the terminals and checking the boots, I must've angered the sleeping giant because the misfires went mad. I was able to get it to register a cylinder 1 misfire P0301, but upon multiple tests and resets of the PCM, there were other times I'd get a cylinder 5 or 3 or 4 or 8 and of course the P0300 for multiple misfires. Cylinder one is the most persistent. Now, I'm aware that bad fuel pressure will do this, not to mention bad compression, injectors, lean o2, or a massive vacuum leak....BUT here's the twist, and I hope it's the problem. I got to thinking, could a dying alternator do this? So I took the negative terminal off with the engine running. The engine kept running, but the interior lights went to flickering, and once I turned on the headlights, the truck died, like I had turned the key off. I was able to duplicate this twice. Do any of you think this is an indication of worn brushes in the alternator? I know when my 95 Cherokee 2.5L alternator brushes wore out, the throttle position sensor actually went to throwing a low voltage error first, followed by the battery symbol on the gauges a few days later. I was able to buy new brushes for like 9 dollars and they're still in the Jeep, and the TPS error went away, so I know that weird electrical errors will happen due to the alternator or battery. Have any of you had misfires due to alternators losing integrity? I have a COP on the way, and I'm aiming to change cylinder one first, since it's the most frequent offender, but I worry with the other misfires that it's a "common" component and not an isolated part as I first thought.

JCR 56

Usually an alternator problem will trip the battery light. You can have it tested to rule it out though. At almost 150,000 miles I'm thinking coils.

Marc D

Alternators don't usually go bad slowly. Because they are regulated by electronics they either work or they don't .I suppose you could find brushes but that's a lot of work. They are about $250-$350 however. If you have intermittent power issues it's possible it's a ground problem. Check all the body to engine ground straps R&R them and clean the surfaces they mount to. Also at 150K miles I'd change all the cobs. This is a very common misfire problem and once they start to fail, they'll all go.

wad_96

In the case of my Jeep, the brushes were getting down to their last few mm of material and they were bouncing on and off of the rings instead of touching them constantly. This caused the engine to run okay at idle with no battery, but once I revved it up, the engine would die. Most likely the speed of the alternator spinning up made the brushes jump like crazy. And as far as work goes, brushes usually bolt onto the back of the alternator on the outside and since you have to take the bad alternator off either ways, this saves hundreds of dollars. The same was true for the starter motor in the Jeep, I was able to spend 21 dollars online and repair the starter. According to what I've researched on the 2004 5.4L alternator, it's about the same process, except a new regulator comes with the new brushes for about 21 dollars. Physical labor doesn't cost me a dime and I will do a little extra work before I spend hundreds on something that simply has a worn brush.

wad_96

Alrighty fellers, I took the alternator off (thank you Ford for making one component intelligently mounted, one 10mm socket all the way around) and upon checking the brushes, one is shorter than the other, but they both have enough travel left in them that they are adequately touching the rings, and it makes 14.18-ish volts at idle, so it's definitely doing its job at idle. What I'm now wondering is if the engine dying when the lights are turned on (with neg batter disconnected) and the misfires are both from what Marc D said above, the engine is not grounding well, which could explain why colder weather has brought out the demons in this thing. So can you all tell me where the main ground to the 5.4L engine is? After doing tons of googling, there are few, if any pictures or discussion on it, but the closest I can come up with is a flat-mesh wire that runs from the firewall on the passenger side and down behind the engine? Am I in the ball-park?

joshtowal

FWIW, it's dangerous to test an alternator that way anymore. Do a quick google search for it if you're curious. And of course the electronics are going haywire when you take the negative cable off. That's the ground path for the circuits. It's almost like cutting halfway through a wire and then wondering why the light bulb isn't working very well.

joshtowal

If you're thinking its a ground problem, just add one or two ground straps going from the engine to the negative post on the battery. You could even add an engine to firewall and engine to frame as well. It never hurts to add more ground paths.

joshtowal

techrep

iTrader: (1)

Replace your COP’s...Check the condition of your FPDM too...

wad_96

I checked the FPDM, I don't know why everyone else has problems with theirs, mine looks great.....both parts of it. LOL! Yeah, when I started to take the bolts off, one of the aluminum bolt holes just fell off with it. Then the rest kinda just crumbled off. I hope this is what's causing the misfires, though I have my doubts, as most trucks actually stall when this thing dies. Either ways it's getting replaced now.