Hooking up a fuel pressure gauge would tell you if it's the filter pretty quick. If fuel pressure drops significantly under a load then I would change the filter and see where you get.
If it seems like I am dragging my feet on this it is only because I am suffering from the same syndrome as Scotty-- too much to do in too little time. Right now I am getting up with the sun to go to work,'get off work and do my jobs at home until sundown,'eat, bath, sleep, repeat. Very busy time of year-- last year I took a week off work and spent everyday doing at least 8 hours of bucking, loading, hauling,'splitting and stacking. But we are getting there. Tonight it's right out the front door and cement a new frame in, mow, split some, plant tree and peppers in the ground, finish filling in pond.
How does it do that unless the filter is in the return? (Which wouldn't affect the fuel supply to the injector rail) Or the test port is upstream of the filter? (Seems silly but .....)
I've worked on a car that lacked power on accel. The fuel pressure tested within specs and the steel fuel feed line was crushed from the wheel lift on a wrecker. The owner failed to mention he was towed the previous day for parking in a no parking zone.
I should have noted that fuel pressure needs to be checked under load...... Get the wife to brake stand it (if you trust your wife..... Lol) or somehow get the gauge where you can see it. Yeah Smoke, I can see that one being a head scratcher.....
Again won't throw a code lamp until a 10% loss is noted ( dang near unrunable by that time) 99 computer will only indicate which bank is running lean or fat. will not indicate particular cylinder. 5.4 is coil on plug no wires, the di-electric strength of the coil boot breaks down with age, shorts to block or sometimes internal in the coil. The computer only sees that the input to the coil has been sent does not monitor the actual firing. Someone else mentioned the the rear most cylinders being the culprits and I concur somewhat with that ( the plugs are recessed way down in the heads so when eng cold moisture can colect in the recess shorting things out). On a 4.6-v8 there was leak in the heater coolant hoses spraying on the the two rear cylinders on the passenger side( side note the heater core had just been replaced under warranty but the dealer did not replace the hoses and their repair of the core caused the failure which of course did not show up until I was 150 miles from nowhere( it was a very very long trip back to an area for parts) the mech. had shortened the hose due to a bad spot at the core connection instead of replacing). Coils run $50 ea. Maybe a little cheaper with some digging. There is one other circuit that can cause this name starts with an Hxxx, I just can not remember it at all. I all ready stated the most common fail points. Electric fuel pump is in the tank after market around $180, oem $300+ these generally fail catastrophically.There is a pick up screen on the pump assembly in tank, it has been noted that once in a while these become fouled. Again if these plugs and coils are still oem that is #2 after the two pcv vac lines from the intake manifold. I chased this on a 99 V10 with $3K+ of the lastest scanner hooked up. Until I replaced all the coils with a matching set (same on the plugs at the same time) I could not resolve the issue by replacing just one coil at a time ( I tried that just cause I can be cheap like us all) swapping it around to try and find that weak one. There is a method to try and measure the coils internal resistance as an indicator of good or bad, this does not always work as the the heat plays a factor in the di-electric breakdown strength. I am about out of gleanings for now, unless I can remember the other circuit name. The good news is that this is not likely a valve train issue- nother whole ball of wax. Note I have been repairing this series of eng ( my own, 46,5.4,6.8-v8s) for the past 14 years and no I haven't seen it all yet)
I had a 98 dodge that would start to sputter and pop basically fall on its face but would go fine at full throttle. Finally figured out a 02 sensor was causing it even though it was not coding. It was a educated guess since it would not do it when cold, only after a couple of minutes. Until the system warmed up it ignored o2 sensor signals.
Does the 5.4 have aluminum heads? Don't just start taking stuff off a COP engine. Those plugs are in there deep. Take the time to research the project first, or pay someone trustworthy to do it. I bought coils off Amazon. A set of ten was $90ish. OEM was around $240. I wouldn't have bought the china junk, but I'm selling that Excursion. If I was keeping it, I would buy Motorcraft. I've only put a couple of miles on them, but it runs much better. 100k is way too long to leave plugs in a mod motor, despite what Ford says. Good luck.
So, it is running much better at the moment-- I am thinking it's a moisture issue. It started the day after a near monsoon, and it's been mostly dry since. I've got the plugs and fuel filter, I will do some research before I just start wrenching. As I said, these might not be the issue, but they are due anyway.
My Excursion would do the same thing. Not necessarily rain, but in heavy snow, and if there was snow and ice buildup at the cowl. Change the COP boots while you're at it. I found the best aftermarket price at oreilly. Just make sure they are the same length. The boots that came with the chinese coils were over 1/8" shorter.
I agree here. Especially if it's a moisture issue, then the packs are the culprit. A set of 10 is pretty cheap. I will be selling my truck as well, but if you buy 10, and only need 2. Then you have 8 left on the shelf and you only spent the equivalent of 2 OEM coil packs.
Nothing could possibly ever run worse in wet weather than the 318 in a '75 Dodge pickup I used to have. It was horrible. I'm selling this dang Excursion, mostly because we don't have a travel trailer anymore, so I don't need a heavy duty family vehicle. I'll be better served by a pickup, I think. Easier than tugging a trailer every time I need to haul something. Reason number two is that I am NOT drilling out broken exhaust manifold studs AGAIN. Actually, it would be drilling out ss bolts this time. I went thru that a few years ago, and I'm never doing it again. Ever. Two are broken on cyl #5, and one on #4, so it's a 'little loud'. I'll take the hit on the selling price. Gonna find me the best pickup ever, a '73-'87 GM. The right one is out there.
The new coil packs will be here Monday. If I find time this afternoon I am going to start breaking the plugs loose. Picked up a new can of PB Blaster just in case it needs to soak.
Started on this, not going any further until I get a extra long spark plug socket. What a pain, got three spark plugs changed, but when you have to resort to bubble gum on a scrench to get your socket back it is time to get the right tool.
Removing the fuel rail makes it easier to get to the back plugs/packs. Just make sure not to snap the two small bolts that go into the intake manifold. . Ask me how I know.. Or ask MasterMech. He seen it as well. SMH..
Did a lot of cussing yesterday, didn't want to post about it last night-- I was very grumpy. Singetreu stopped over afterwards and I was so mad at my truck that he though I was mad at him! Anyway, three plugs changed-- I did take off the drivers side fuel rail. My socket was too short and kept getting stuck in the plug wells-- felt like I was playing ET for the Atari 2600. Finally I tossed my wrench, went in the house at found a ten in long socket on Amazon. It will be here Tuesday. Supposed to trek the truck to Wisconsin on Thursday night, if I have to would there be any harm in having only the front half of the plugs switched and do the other 4 either when I get there or after I get back? All the coils will be changed and the cylinder reporting the error will have been swapped. This is a worst case scenario.
