I have a 98 F150 with the 4.6L engine. Upon start-up, after sitting 2-3 days without being run, the engine seems to be running on 7 cyclinders. After warm-up the engine runs just fine. I have 67K miles on the vehicle. I suspect that the problem could be caused by oil leaking onto plug due to bad oil seal.
Is this possible? Has anyone else had this problem?

jph

 

4.6's are known to have poorly designed spark plug wires. They have been revised a number of times. Are yours original? I'd start there.

Is there visible smoke? I've seen 4.6 cars smoke some but never a truck. It would take very large amounts of oil to cause a misfire problem.

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97 XLT S/C Long Bed 2wd, 4.6 Romeo, 4R70W Trans., 3.55 LS, 197,000 miles

 

I started my truck the other morning,and it
acted the same way. It was shaking like it
had a fouled plug,but after a few seconds
it smoothed right up like nothing was wrong. This was the first time anything like that has ever happened,and it was very unexpected to say the least. No check engine light,and the next time I started it cold,it ran fine. Bent6,If a plug wire has been arcing,do they have a large
whitish stain on them where they contact
the other wires? I have my originals,but I
will change them soon,along with new coil packs,plugs,and a Jacobs ignition,,,98

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98 F-150 4.6 Litre XLT2wd Ext. cab
Yokahama AVS/ST's
prarie tan/tan int.
K/N gen.II fipk
custom dual exh/gibson rectangle tips/rear exiting.
color matched snuglid
Superchip!!!
Westin nerfs blk .powdercoat
Clear front corners
Euro tails(Altezza style)
Cobra 75WXST cb w/weather alert
[b]Kenwood cd w/Radio Shack speakers,don't laugh it sounds pretty good]
Viper 500HF Security system
On the way/wheels,tires,air dam, etc..etc.......
doin the monochromatic boogie
on the front end.Billet grilles on order
www.my-f150.com Still want to lift it,YESSS!
FENDER GUITARS,ROCK!!!
http://www.bigsandy.net
officialtomwaits.com
reverendhortonheat.com

WOW,what a cool site!

 

Bent-Screamer

Thanks for your input.

The wires are new and not original. I did think I saw some blue smoke in my passenger side mirror. The truck does not smoke otherwise. If this happens again I will watch more closely.

Screamer, your description of how your truck runs could be a description of mine. This only happens if the truck sit for a few days otherwise I've had good service from this truck. I will start checking the oil more often.

Thanks

JPH

 

Just grasping at straws here, but could a bad injector leak enough fuel over a period of time to cause this problem yet not cause a problem while the engine is running?