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2004 Ford F-150 - Jerkiness

My truck has a hard jerk at times while accelerating. Sometimes it will be multiple jerks. Usually happens when going between 30 and 40 mph. If I accelerate slowly it won’t do it. Usually happens when accelerating up hills.

More info please. Is the check engine light on? How long has it been on?

Since my crystal ball can’t read what engine, transmission and mileage, you are going to have to tell me this before we go further.

Hi,
Yes, I can see how those things would be important. 5.8L engine, 118,000 miles with automatic transmission. Don’t drive this truck very often, maybe 2000 miles a year. It has been going on about a year. After it first started it wouldn’t do it every time. Recently, it seems to do it almost every time I drive it.

Thanks for your response.

I suspect lack of use is a contributing factor. You might get by with a new fuel filter, a full tank of fresh gas and a bottle of fuel treatment such as Techron, followed by a longer drive at highway speeds.
I would also replace the spark plugs.
I hope you are doing, at the minimum, annual oil changes.
When not in use, to reduce moisture absorption, fill the gas tank.

Agree with @Purebred I would add, clean the throttle body.

You didn’t say whether the check engine light was on.

Sorry, no engine light. This may be a red herring, but this started to happen when I moved to Maryland. I bought the truck used in Utah where I drove it for a for a couple of years without any problem. The truck was really taken care of by the previous owner. I don’t know if the lower altitude in Maryland as opposed to the 5,000 foot elevation in Utah could be a factor.

Thanks again

Thanks Purebred. I was wondering if lack of use could be a factor. I do regular oil changes, but not sure when the plugs or fuel filter have been changed. Could the altitude make any difference? I used the truck for a few years in Utah (5,000 elevation) with no problems, and almost immediately after getting to Maryland (50 elevation) this started to happen.

Thanks

I don’t think altitude would be a factor. As far as I know the computer will make any air/furl ratio adjustments, unlike carbureted vehicles of old.
However, Maryland is much more humid and the ethanol absorbs a certain amount of water, which might be part of the problem.

Thanks again for the info. I’ll try your suggestions.

2004 half ton Ford with a 5.8? Are you sure?

Either way, I’d try a bottle of Heet. Or a fresh tank of fuel. Actually, both.

Also, I’d change the plugs if it hasn’t been done, or if it’s unknown when it was done. The 2004 5.4, I believe, had an issue with plugs breaking off in the heads. Goofy plug design. So I’d change them. Like right now. Else you might not get them out later.

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Good to know. I will get those changed right away.

Thanks

Forgive me if my thought is based on ancient technology, but in this situation I’d just routinely replace the spark plugs, and the high voltage cables. The cables get old, develop micro cracks, and can “leak” electricity and create misfires and cross firing. Low humidity will hide this, but when you move to the damp East Coast it would show.

Maybe your engine has separate coils for each plug like a modern setup?

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Thanks for your reply. I am getting the plugs changed this week and if that doesn’t do it I will have the cables replaced. It is suspicious that it started as soon as I got to Maryland.


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Since other systems have been mentioned I will only add one other oddball possibility. That is the chance of a split in the hose to the PCV valve.

Some years ago my Lincoln started acting a funky with a jerkiness only at around 45 MPH. Foot flat on the floor no problem at all and it would usually only do this while accelerating midly out of a sweeping turn.

I finally discovered a razor blade like slit in the PCV hose. What was happening is that most of the time the slit was closed. Under moderate acceleration the slit would open up which then caused an air leak which in turn affected the MAF sensor. No CEL, no codes, etc.
I replaced the hose and problem gone. Just something for consideration.

Thanks for weighing in. Sounds similar to what is happening with mine.


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Plug wires affected, maybe. At least remove them and clean them and around the plugs and posts and make sure they’re plugged in securely.