Misfire on acceleration

Hello and thanks for any help I may get. My Expy has 138,000 and really has not been much of a problem. Its started to jerk and sputter under any acceleration but starts OK and cruises OK. Passing is out of the question.
I suspect coil packs per this forum posts, but invite confirmation/redirects if anyone would care to assist. No codes have been found so far. Plugs were renewed at 100k at the dealer.
For info sake, previous issues are speed sensor on trannie caused flashing AWD light. All fluids changed on schedule. Still on original wheel brgs, shocks, almost everything physical. Lucky, huh? Thanks!!

jerking and sputtering should trip a CEL, but if you're not getting any codes, you might try some fuel system cleaner or such.
also, what year do you have? i have 151k on my '97, had 4 coil failures, and 1 spark plug blown out of the head.
there's a EGR vacuum line at the back of the intake manifold on the passenger side, directly under the IAC valve, it rotted out and caused a big vacuum leak
hth in some way
Rick, Ore

jerking and sputtering should trip a CEL, but if you're not getting any codes, you might try some fuel system cleaner or such.
also, what year do you have? i have 151k on my '97, had 4 coil failures, and 1 spark plug blown out of the head.
there's a EGR vacuum line at the back of the intake manifold on the passenger side, directly under the IAC valve, it rotted out and caused a big vacuum leak
hth in some way
Rick, Ore:

Mine is a 97 too. I replaced the rotted hose that connects at the back of the engine (to the EGR or idle control can't remember.) I must say it does still idle high at lights, yet not all the time. A vacuum leak would be consistant, yet as it is occasional think related to something else. My big problem is still the horrible jerking and lack of power under any acceleration. I put fuel cleaner in sometimes, but still leaning to the ORIGINAL coil packs. Maybe worth replacing them all? :banghead:

Hi there!

I've recently purchased a used '97 Expedition XLT (5.4L, 4x4, 247000km) too. Although I haven't had the misfiring, I DID have a spark plug that was loose - like hand-tight! That really made the fuel consumption take a jump and it sounded terrible. I initially thought I had a valve lifter on its way to needing a repair. Fortunately it was the loose plug that I found early enough instead - much easier/cheaper to remedy.

The plugs are a pain to get at if you have a 5.4L since they're on top of the engine among the various hoses/etc..., but I'd say it's worth the hassle to check them out. (Changing them at the same time would be a good idea too - you don't want to have to do that job again anytime soon.) Make sure the engine's cool so that you don't mess with the plug/head bore threads.
Now I notice a huge improvement in fuel efficiency and the truck runs much more quietly now too. FYI - I used Bosch Platinum plugs as replacements. I've used these in my Sable as well and they work great!

Interesting to hear that another owner had a plug blown right out of the head. That's some powerful compression!

not really! just poor head design/machining of the spark plug holes! the constant pounding of a loose spark plug, regardless of compresion, will eventually blow the threads out of the head, when that happens thiers only a couple options, try to have it repaired ( if possable= expensive) or have the head replaced ( way more expensive! )
mine cost $480 to have a insert installed, i didn't even want to price a head!
hth
Rick, Ore

2 sparkplugs blown (#4 twice) for a $1200.00 bill and 4 coils replaced. I'm starting to get the hesitation on acceleration when it is cold and around 1500rpm it hesitates. When the thing is warmed up it is not near as bad but still happens especially when starting off from red lights and so on. NO codes yet. With my 4 other COPs I got cel and codes. Anybody got an idea? Can the COPS and or plugs ( Motorcraft replaced 20K ago ) misfire without generating a CEL?

Hello My 99 exped did the same thing after I washed the engine. It finally stopped after aweek. It would'nt throw a code till I romped on it. Just after that I had a #8 coil go out. I have 104,000 on my 4x4,nothing ever major wrong yet.