Need some 5.4 help

[kirk]

Took a 300 mile trip in our 2000 Expedition yesterday. First half of the trip went fine. On the return trip it started missing under MODERATE load ONLY.

With the cruise set on a flat road it's fine. Start going up any grade and it starts missing and jerking. Go WOT while it's missing and it straightens out and runs fine. So it's not a fuel delivery issue.

Has 146,000 miles on this 5.4, and I filled the gas tank 70 miles before the end of the trip, which made no difference. No check engine light yet. Skips a little while idling also.

Any thoughts on where to start?

[martyo]

Scan for codes and report back.

[Marauderjack]

Has it got "Springy Connectors" between the coils and plugs??:confused:

Could also be dirty/sticking EGR valve??:cool:

[Fastbob]

Have the spark plugs been changed or are they original?

[fastblackmerc]

My guess would be:

Plugs
Coil
Maybe fuel filter

[kirk]

My guess would be:

Plugs
Coil
Maybe fuel filter

It's not the fuel filter, but may be plugs or coil. I'll scan codes and report back.

[justbob]

My best guess would be coils as my '04 5.4 lariat does this as well and everything on it is new except the coils.


Builder Of Badassery

[massacre]

Sounds like ignition to me (COPs, plugs)

[yjmud]

I would be looking at the coils

[kirk]

Scan for codes and report back.

I come here because you guys are smart enough to tell me to get off my butt and do the things I know I should do already. Too easy to sit down and start typing instead.

P0305 - #5 misfire

No obvious signs of a wire loose. Is there an easy way to test the coil? Resistance? 4-10k ohms?

Would you do 1 or 8? (assuming it's bad)

[RF Overlord]

Swap #5 coil with any other. If the code follows the coil, replace it. Some will say replace all 8 and that's certainly valid, but I had one bad coil in Mary's car in July of 2011...I replaced just the one and the rest are still going strong...

[88grandmarq]

agreed... check it for store codes.

I have worked on several of these truck lately. New Motor craft plugs, coil boots and dab of di-electric grease on either end of the spring in the boot seems to work wonders.

There was a TSB back in the day for the 5.4L 2v engines in the expedition and F-150. water was draining out of the cowl area, dripping on the rear of the engine and would eventually fill several of the spark plug tubes with water. obviously, this caused corrosion and a mis-fire.

http://i1033.photobucket.com/albums/a414/88grandmarq/2005%20F150%20No%20Reverse/54L_plug_zps22007fea.jpg

http://i1033.photobucket.com/albums/a414/88grandmarq/2005%20F150%20No%20Reverse/plug_boot_zpsece1baa6.jpg

[Fastbob]

Look closely at the spark plug boots, I have seen them with a hole arced through them. This is easy to miss.

[fastblackmerc]

It's not the fuel filter, but may be plugs or coil. I'll scan codes and report back.

That's why I said "maybe".... :D

[Turbov6Bryan]

Quality of fuel?

Pull some fuel out and put it in a mason jar, check for water.

Great suggestion at swapping the coil and see if it changes to another cylinder, you can do it with the injector later on

I've seen tons of problems related to water in fuel lately

Hope you find it out Soon

Bryan

[Ms. Denmark]

I had the same issue with my Aviator. Turned out to be a bad COP. It was replaced and the truck ran fine for a couple of years then the other COPs started to fail. I recently replaced them all and the truck runs great.

[MM in MN]

That is exactly how my 2002 F150 behaves when one of the coils go bad. Over the years I've probably replaced 5 of them, but, hey, its got 250K on it and that's the only problem it's ever had, so I'm not going to complain. IMHO just change out the bad one.

[kirk]

New #5 coil.

Runs like a fine Swiss watch.

Thanks for the help gang!