I have a 2004 5.4l f150.280,000 miles. Recently changed the rocker arms in it. That fixed that problem. It ran great for about a week. Great mpg and all that. Then it started kinda idling rough. Sometimes really rough. It wouldn’t throw a code for the longest time but finally did after I hammered it on the interstate for a couple miles. Got off the interstate and it was idling really rough. It finally threw a code for both cam sensors. Hasn’t done it that bad since. Could the cam sensors be the issue? Don’t want to waste time and money buying and installing if that’s not the issue. If it was just the code I’m going by I would, but I’ve taken all the plugs out twice and cleaned was looks to be rusty orange stuff off of them. That seems to help until I drive it another couple hundred. Then mileage goes back down. I’m really confused on what it could be. What’s causing the plugs to do that? Been working on my own vehicles all my life and haven’t encountered this before. Maybe the cam sensors are bad and causing a delay in spark ignition? Please help
maybe it's burning something it shouldn't. have you tried a compression test?
Yeah compression is good on all 8 cylinders. The residue is on all 8 cylinders as well. My first thought was rust. But not sure how all 8 would be getting rust unless I had a bad head gasket. But it has no other signs of bad head gasket. Doesn’t burn coolant. Coolant levels have remained the same. The plugs aren’t exactly cheap for this thing either. $14 each. So I don’t want to throw money at it unless I know that’s the problem. But 4 plugs are new and they’re doing the same thing. It’s got me puzzled. So I’m just kinda guessing the problem doesn’t have anything to do with the plugs at all. I haven’t hooked it up to a live data scan tool yet. I feel like that would be my best option
what exactly are the codes?
P0340 and P0345
Since both cam/crankshaft sensors are affected, I would check the wiring harness grounding point for them. Using a schematic, I would then check continuity on the cam/crankshaft sensor lines.
Yeah it seemed kinda odd they were both triggered in the event. But then again it has 281,000 miles so it wouldn’t surprise me if they both weren’t actually bad. But wiring does seem more likely. Would it be the main ground for the wiring harness? The one that’s attached to the fire wall?
Joe is likely right here... but loosen and then retighten them...a low current resistance test may appear ok when it's not.
my bad. Those are both camshaft sensor codes. This looks like a useful read:
https://www.ford-trucks.com/forums/831741-5-4-3v-woes-p0345.html
Yeah I figured that was a typo. One code is for bank one, other for two. But I appreciate the help. For the most part it drives good. Just gets roughly 14mpg rather than the 17-18 it use to on the highway. That and being sluggish. Just wish it would throw a code again. I erased those 2 it threw just to see if it would throw them again. Hasn’t yet. That’s why I’m not so sure it’s the cam sensors. But it’s all I have to go with as of now. I’ll let you know if I get it solved and what it ended up being.
My last comment was kinda misleading about the mpg. Some days it gets 17-18. But more than not it gets roughly 14. (The truck has a built in mpg calculator) So it’s not a constant issue. Prolly 4 out of 5 times I drive it’s sluggish. Seems like something is going out but hasn’t all the way yet. That makes it kinda frustrating trying to figure it out.
I had a 04 f150 5.4 3v I had that issue the first thing I would try is get one new cam sensor it’s only like $25 and it works on both sides so you can swap it side to side. Next I would replace the VCT solenoids please for the VCT only use Motorcraft parts. If that doesn’t fix your issues you have some serious problems and it will likely a new timing setup yes I know you can get a timing kit for like $400 but do not do it don’t buy cheap parts that are based on a flawed design once again only Motorcraft parts. I purchased my parts for just under $800 and did it in two days it was quite difficult. Lastly after I did the timing job on my motor I still had issues with the truck and I was very confused I used my plug tester and volt meter to see how much juice my coil pack wires we’re putting out and I ended up replacing 4 of them and that truck ran great so I sold it while it worked. Hope that helps.
