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125,000 miles on this 4.6L V8. Recently, the engine has been running rough. Doesn't crank right up in the morning. Misses a lot when passing. Just lost its oomph.
I usually run 87 octane fuel, but today, on a whim, I pumped 93 octane and it made a HUGE difference. The miss is undetectable.
Could I have a timing issue? Something else?
I am the original owner and have pampered this vehicle with regular maintenance.
There is like to be something wrong that requires higher octane if that's the case. Like the EGR system that feeds alittle burn exhaust into the engine that basically retards the burn rate of the fuel which is what higher octane does. Normally you get valve noise from too low octane gasoline.
There is like to be something wrong that requires higher octane if that's the case. Like the EGR system that feeds alittle burn exhaust into the engine that basically retards the burn rate of the fuel which is what higher octane does. Normally you get valve noise from too low octane gasoline.
Thanks. BTW- The CHECK ENGINE light has NOT come on.
My guess is that the coil packs starting to go bad. At least that is what happened to my 1998 F-150 after it started behaving like you describe. If it is the coil pack, it will get worse and the check engine light will come on. Then you can get a reader and figure out which one it is. It costs about $50 to do yourself and it is easy, or you can pay $200 for a dealer to do it. remember, there are eight of them and at least for me, once one went bad, most of the rest quickly followed. So for a dealer repair it eventually costs $1600. For DIY the total is $400.
I saw online that a lot of time it is just the boot getting cracked and grody. You can replace the boots and or wires and everything will be fine. That did nto work for me. The coils were bad.
If the entire problem went away with premium fuel, could be carbon buildup, or could be EGR not opening enough or flowing freely, although it's not gotten to the point of setting a CEL. .
A near-no-cost experiment would be to run the truck down to 1/4 tank of the premium fuel, then fill it up to about 3/4 full with regular. If the problem comes back, that more or less proves increased octane is a temporary cure.
AutoZone or similar will check for trouble codes for free, it's worth the time to check. Some trouble codes "set" the light, such that it stays on, some don't.
Maybe look into running some SeaFoam through it. I've done it in my former '02 and my Grandfather's '01 and it made a good difference. Shouldn't cost any more than $10 to do it. Just make sure your neighbors know about it in advance or they'll more than likely call the fire department. You WILL have a LOT of smoke come out the back.
To do it, disconnect the vaccuum hose from the brake booster and stick it in the can of SeaFoam. Keep the throttle depressed enough to keep the engine running. Shouldn't take more than 15 seconds. Hook the hose back up and take it around the block, driving in a very spirited manner. Blow all that crap out the back.
If the entire problem went away with premium fuel, could be carbon buildup, or could be EGR not opening enough or flowing freely, although it's not gotten to the point of setting a CEL. .
AutoZone or similar will check for trouble codes for free, it's worth the time to check. Some trouble codes "set" the light, such that it stays on, some don't.
You were this/close, Mitch. AutoZone ran the codes. P0401. Replaced the DPFE sensor ($51.99) which is part of the EGR system. About a 10 minute job for my inexperienced hands. I would say it fixed 95% of the symptoms. It still hesitates ever so slightly under full load (my foot all the way in the pedal getting on the highway). Good enough for now.
Another DIY success story. Putting the lie to that crap "oh, ya can't work on them new computer-controlled carz, yup, yup, gotta take 'er to the deeler" BS, I say.
BTW how old are your fuel filte and plugs? Generally you should do the fuel filter every 30K +/- miles, but look in your manual, it should say. On 2 of 2 older Japanese cars I have bought with overdue fuel filters on them, although no CEL was set, they started and ran "fine", both picked up ~5% improvement in MPG.
Keeping good "sharp" plugs in it will make the coil pack's life "easier" and as you see from Coldjensens' experience these cost a lot more than plugs.
I'd put some chevron techron in the fuel and run it on the highway because your bound to have some carbon on the valve seat areas because with the regular acting like even lower octane with the EGR system problems.
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