'99 f-150 ruff idle

[dakotakid31]

i have a '99 f-150 with the 5.4 that started idling ruff when i put it in gear(auto) jumps from 5-6000rpms. started doing it half way to mille lacs..said screw it and kept going. made it there and back with the boat but the engine light was flashing which in the manual says it is missfiring. i should put her in her grave (175000 miles) but wanted one more winter, even my son tells me i need a new truck when he rides in it. i wont be able to get it into a shop until next week so i was just wondering what all you wrench heads thought of it. fuel pump? coil packs? i know it could be many things just wanted your guesses.

[Shack]

9 times out of ten coil over plug. I would go to local parts store and see if they will scan it for free and see what cly. it is. Could be a cracked or worn plug.

If you take in it would cost you around $180.00 to $250.00 for one coil over plug installed. Should include Diag.

Good luck!

P.S.

It is probobly raining when it started to run rough!

[ChuckN]

I'll take a guess that it may be a coil failure (but a computer diagnosis will definitely tell ya.. ). I had this happen once years ago, don't know which number coil, but it was the far back coil on passenger side. My mechanic friend said there is a common coolant leak out of a coolant line above the coil and the moisture shorted out the coil. He fixed the leaking hose and no more problems. Definitely get the truck looked at...

[Shack]

ChuckN,

You are correct! The coolant heater by-pass hose would leak anti-freeze onto coil.

[Scott K]

The coil packs on these are a very comon problem, if you can get the code pulled by someone, I would replace all 8 plugs, if it hasnt been done recently, then replace the coil pack on the cylinder that has the code. The #4 has a heater hose above it that the screw clamp leaks on them, there is a updated hose and clamp. So if it is #4 check the hose above it also.

[fishhook8]

I had a 98 f150 6 cyl that start running really bad. I took it in they told me the converters were bad and wanted $2700 to replace. I took it to a guy in Monticello he would replace them with and after market for $300. He check them out and said they were good. I put some seafoam in the gas tank it did wanders, every couple months I would do the same.

[Scott K]

Mechanic in a can!! It can clean internal engine parts, and loosen up converter particles. But its not the answer for everything. I think in this case, he has a bad coil pack. Pretty easy do it yourself fix, just as easy as replacing plugs. OK in this case its not really easy, but the average joe should be able to replace a coil pack and plugs.

[dakotakid31]

the plugs were recently replaced. it wasnt raining when it first happened. the dude at the ford dealer was trying to tell me it sounded like a fuel pump- but i always thought they were like a light switch, it either worked or didnt. coil sounds like the deal. i dont think they make an engine that is easy to work on anymore!!but changing out a coil shouldnt be to bad. i will find somewhere to scan it to narrow the search.oh and i already dumped the seafoam in the same day.lol...always worth a shot.the truck is only used for towing the boat or hunting i drive a work vehicle and the reason i dont want to buy a new one yet is because i am not sure what i want. this truck is like frankinstien- 30k had the engine replaced by ford due to a bad head gask that tore the engine up.74k i was one of the many lucky ones that had a spark plug blow out the head but the tranny is original and has never had any problems-well until i just jinxed myself. but hey thanks guys i knew someone would have some ideas.

[Scott K]

If you get in scaned, let us know what you come up with.

[trackerbrent]

If it is a coil, from what I have read on them, there will be more coils going bad to follow. You can get a set of 8 aftermarket coils off of the big auction site that starts with an E for around $120 for the whole set. I know guys that have been running them for 2 years and no problems. Worth a shot, rather than spending $200 at a dealer for just 1 coil on plug.

[wplatehunter]

I had the same problem with my 2001 and it was the coils. I also replaced the spark plugs and the bill was around $800. I replaced all the coils. Good Luck

[Shack]

Mouisture is a funny thing. Concern with rough running is there one moment and gone the next.

One back yard mechanic thing to try is to perform a hot soak test. Get eng. up to running temp and spray down with water. You trigger a miss fire code or eng. starts running funny, it is a ign. type concern. Cheap and easy to do and also rules out fuel pump!

I seen it done at dealership 2-3 times a day to figure out concerns.

What dealer did you bring it to ER or Monti?

[Shack]

I would rather replace the coil or coils that are failed. Just spend the $15-$30 dollors, instead of all that work and $120 dollors. If you have to buy the whole 8 of the C.O.P., save the good ones and replace only the bad one at that time.

Some peole have problems others did not. I have seen one coil replaced in 150,000 miles and I have seen all 8 replaced in 30,000. Its a crappet shoot!

Good luck!

P.S.

Good tip on were to get coils cheap

[Scott K]

Quote:

---

Mouisture is a funny thing. Concern with rough running is there one moment and gone the next.

One back yard mechanic thing to try is to perform a hot soak test. Get eng. up to running temp and spray down with water. You trigger a miss fire code or eng. starts running funny, it is a ign. type concern. Cheap and easy to do and also rules out fuel pump!

I seen it done at dealership 2-3 times a day to figure out concerns.

What dealer did you bring it to ER or Monti?

---

Shack, the water trick works great, on engines when the plugs go through the sides of the engine, but when the plugs go through the top, like the 4.6, and the 5.4 water will soak down into the plug area and will short out the coil packs. Such as the #4 with the coolant leak on the cop.

These coils do not like water at all, if you ever wash the top of your motor, plan on buying 8 coil packs, you will need them in about a month, 1 at a time! Over the years of working on cars, the water spray bottle has worked great for all the other engines to diag missfires, I would grab the spray bottle soak the wires, load the engine and look for my arcing wire. But that doesnt work with the engines with the plugs going through the top of the engine, water will just soak down and short the coil, or wire out.

[Shack]

I figured it would cause a weak point to show its self, but if every thing is working as it should, water should not be an issue..

Maybe it was tech's looking for future work when I have seen it done on 4.6 or 5.4 .

[dakotakid31]

it was the monti ford that said that. debating weather to stay home from up north this weekend to mess around with it or say screw it till next week...lol. i took a look and that coolant hose is not leaking at all and i should be able to get at all the coils..but what a joke.

[Shack]

Bumper to bumper or checker in monti should be able to scan! At least let you scan with their scanner! I think all you have to do is leave Drivers Lic. at counter and they let you bring scanner out to your car.

If not try advanced auto in Elk river by walmart!

If it is a coil, it will not hurt to drive a while! A little poor fuel econ and check eng... I would tae care of first, but in a pinch it would not stop me from driving to work or on a major run! IMO!!!

[dakotakid31]

well you guys are good!. went to oriely's and borrowed the scaner- #5 was miss firing. replaced the coil pack( one of the easiest ones and it still blew goats) runs like a champ now...thanks fellas!!

[Shack]

Good to hear!