97 expedition 4.6 miss fire on 4, 5, 6, 7, 8
I know its not an f150 but couldn't find a section for the expedition. Figured its the same motor so you all could help. I bought it for cheap with a bad miss fire not sure what cylinders just did a tune up. I forget but I think they were motorcraft spark plugs I put in. But after that it ran grate so I thought. It would be intermiten but would all of a sudden while accelerating get a boost of power. That would last untell its next shift point and would always happen around 2-2500 rpm. Kinda like VTEC in a honda. Or it gained 2 cylinders. And would also start stumbling while sitting at a stop light for two long with it in gear and break on only after its warm. Never happens when cold. I hooked up tourqe and saw when it does it its misfiring on 5-6-7-8 randomly. Its missing on cylinder 4 all the time now which I believe is a plug, wire, or water-antifreez in plug hole sorry for the long intro but hopefully someone can help me out here. Its my first triton I'm usually in the powerstroke world thanks again.

 

All on one side? Sounds like a head gasket leak to me, either warped head or a blown out gasket. Another thing could be worn/broken timing chain guides or tensioner on that side, or bad wiring to injectors or coils on that side, though the bad wiring would give you a CEL and codes to read in torque. Bad timing components or leaky head gaskets don't always give codes. Do a compression test on it, and see where it's at. Leaky head gasket = low compression, while bad timing guide or tensioner should still give good and normal compression.

Other than that:
For engine hesitation, try to clean the MAF, and check for vacuum leaks and check air filter and fuel filter.

 

ok i will do a compression test on it and see were its at. this one has the two coils up front, does this motor have two separate timing chains/belts for each head? if not i would think it would do it on all cylinders??? thank you for the reply this sat in the f150 section for a week or so (thats why the f150 part is in my original post) with no ideas. i found this section today so posted over here in hopes of more help.

 

Yes, with the dual overhead cam setup, there's one chain per cylinder bank.
I really believe that the chain tensioner components on that side are damaged or worn. then on the other single cylinder there's a wire or coil problem. But that's just my guess from all the way across the interwebs. The compression check is easier than getting into the timing equipment.

 

I will do that shortly. I am going out in a bit to work on it. I think it may need a new plug but who knows. I'm hoping to find a little coolant but it looks like that has been an issue before there is a hose clamp up there. On another note is there a special way to bleed the coolant system. The heater gets cold if we sit but gets luke warm when driving. I hear the water circulating in the heater core when I get on it. Kinda seems like there is air in the system...

 

I think I may have found the problem, the number 4 spark plug had the ceramic broken off on the inside. spark plugs 6, 7 and 8 had water down in there at one point and was all rusted. So it got new motorcraft platinum double iridium's or something like that.

 

Well still getting random missfires on a 20 min drive I picked up 1 on cyl3 20 on cyl5 13 on cyl6 1 on cyl7-8... None on cylinders 1-2-4

 

Will plugged cats on one side cause this??? Also I was accelerating up a hill the other day and everything was normal then a huge burst of power like I hit the go button or something. Acted like it went from a 6cyl to a v8. Getting on the freeway I have to put the pedal down for it to get up to speed decently. This is my first one so I'm not sure what to expect power wise. Does seem a little under powered.

 

Even the "lowly" 4.6 should accelerate quickly. It's not a pushover when it comes to power, it's just that some other engines are bigger and stronger. I'd wager that once the issues are found and addressed you'll be at full power.

 

I've seen this happen before and most of the time it turned out to be an issue with the fuel injectors.

 

Is there a way to see if its the injectors while there still in the rig, besides ohm them out. And when its cold it runs really good no hickups shuttering at stops nothing.

 

I don't think the injectors have any electrical issue, ohming them out will likely not show anything out of order. The reason I'm saying this is that if there was something electrically wrong with the injectors, it would quickly throw a code and be easy to pinpoint. You could always try to ohm them out just to be sure, but I suspect that if there's an issue with the injectors, it's either that they're clogged up and needs cleaning or some other internal mechanical issue.

 

How old, and what kind of shape are the sparkplug wires?

 

The ones i just pulled out were about 7 months old maybe 5,000 miles on them. the motor craft double platinum have 100 miles on them maybe. wires were replaced when i put the auto lights in 5,000 miles ago.

 

So are all your plugs now motorcraft ones? Or autolight? Or a mix?