Terrible fuel mileage- please help!

[281exploder]

Let me partially agree with you , timing chains/guides/tensioners/etc. better ( better- because it is up to the vehicle owner to do ) to be replaced after around 100-150k miles (chains and vvt sproket worn out , tensioner seals gone bad ,guide plastics became brittle etc.). I dont believe this parts last forever even they are much more reliable than timing belt mechanism.

BUT

In this thread case ,without any timing or misfire related DTC , no any reason to change the timing kit.there is 1000 more, high mileage related reasons for the bad fuel economy before changing the timing kit.

this is a true statement. but I have seen plenty of examples in the shop with timing chain slack throwing no codes just running werid. usually the idle is off. and they are one doorstep away from blowing a engine if the engine itself is interference. so imo is not something to be taken lightly and put in to account this thread OP said timing chain has never been done.

 

[94Eddie]

I will post a picture exactly where it states to change timing chain every 100,000 miles which OP hasn't done yet at all and it's past 200,000 miles. so again like stated timing chain should have been done twice. and to clarify what I said, if you want peak mpg at that mileage your going to have to do a lot to get to that peak mpg. like cleaning and rebuilding everything and that's just a fact if you don't want to admit that then I'm beating a dead horse at this point. did I say it needed it done? no I said if the engine is running fine then don't worry about basically. the funny thing is you keep referring to your explorer as a 200k mile example. if you don't know how to use the search bar to look for other timing chain examples then I suggest youtube. if you weren't so lazy and dug down enough in the thread I linked multiple people were reporting having premature wear.

I am waiting on that link.

I am getting EPA stated MPG, and even better, at 150k miles on the original major engine components. What is your definition of an "engine running fine?" What symptoms warrants an engine needing the timing chain and guides replaced? You made a recommendation this is needed for low MPG without considering any other reasons for why the MPG might be low. If you are going to make extraordinary statements then be prepared to back them up.

I see the problem here, classic one.

I said i would post a picture because I could have sworn i seen a interval in the service manual but clearly I was mistaking but not entirely wrong.

ford marketed there timing chains as lasting forever just like how mercedes does with there trans and diff fluid. if your a fool in to believing that crap then I'm definetly beating a dead horse. so anyways there are no intervals from the manufacturer for timing chains BUT! any other engine should be 80k-120k miles when timing chains should be done and if you go on the f150 and mustang forums guess what, everybody has timing chains problems from 100k-150k miles because the tensioner wears out and then slack happens then the chain eats itself. so do what you want with that info. timing chains don't last forever i know that much. and I also had timing chains problems in the past on a bmw with only 112k miles, which created poor mpg and blew the engine because it was interference. so it's not like i don't know this topic. despite comparing apples to oranges from my experience.

Are you now saying Ford doesn't recommend 100k timing chain and guide replacement? You need to parse out the 4.6L 3V engine in the F150 from the 5.4L 3V engine. The 5.4L 3V is very susceptible to extended oil change intervals. The problems it has does not replicate with the 4.6L 3V engines. Timing chains and guides are not a common problem with the 4.6L 3V engines no matter what vehicle they are placed in. I know you are dug in on your claims regarding the 4.6L 3V engine, but they are no where near justified based on actual real world data. IMO, the biggest long term, major issue with the 4.6L 3V engine is the roller followers in the rocker arms. Even then, this type of failure is a rare occurrence.

 

[jr230]

So I am in Alberta, Canada. 340,000 Km’s or 210,000 miles. I bought it new. Better than religious with oil changes and always with synthetic. Wife (gone now) drove it lots in the early days but not aggressively. I performed near every maintenance and repair personally. Transfer case fluid was only fluid NOT changed religiously. Never used to tow anything. It is a driver selectable 4 x 4. Almost never used. Fluid in rear diff changed regularly.

taking in the harsh winters, 210k miles us. your about to about where its worn out . 12-13 mpg in mixed city highway is average but ticking, and the manifold bolts ticking your going to need cam work it goes from ticking to rattling not gradually worst . if you haven't had the deep scanner not just code pull try that . check fuel pump pressure , but honest after owning 99,02 and 04 start shopping for a motor probably not a 3 valve if your able to do the swap it shouldn't be too expensive the deep scan could show any problem with the trans . my 04 had cam go
around her 3000 labor plus about 900 parts sohc v6 unfortunately newer explorers with decent odometer and price were found drive or 4 cyl ford destroyed the explorers even going back to rear or 4x4 but then a 4 cyl unless you buy the 60-70k model .even with Canada gas price
if scan doesn't find something could get another yr meanwhile keep eye out for a occasional low milage one thats how i got my 04 looked at about 15 over a yr driving the almost dead 02 but in 18 found less than 100k miles for 2000 and ran it for 5 yrs and put about 400 in maintance battery and repair worst the key lost contact and only had 1 pita