DanAustin

My brothers 07 lariat has 82k miles it has a bad stumble between 40-50 mph when you lug it up a hill if od is off it never misses a beat. It missed bad and bucked hard so after doing some reading did the plugs and all 8 coil packs. Now that that's done it doesn't stumble as hard but is still very noticeable and seems to do it longer. We changed oil fuel and air filter plugs and all 8 coil packs no cel lights no codes about to drive down the alcan from anchorage ak to Lubbock Texas next week pulling a trailer and want to get it figured out before we leave. 5.4 non flex fuel

vintageman

What brand of plugs and COPs did you use? Any codes coming up?

DanAustin

Motorcraft plugs echlin cops no codes at all

vintageman

Never heard of echlin cops but you may want to start at checking each cop. Start the engine, and one at a time, disconnect a cop wire, the engine should act different, plug the cop back in, then unplug the next cop. When/if you find one that does not cause the engine to sound different, I would then swap that one with one of the other good ones and try the unplug process again. That will help verify that the cop was bad if the symptom moves to the other cylinder. If it stays at the same cylinder when you unplug the cop, then I would suspect a bad spark plug before diving into the wiring harness plug being bad. Let us know what you find, good luck.
Tom

powerranger262

Clean your throttle body and MAF.
Was it raining when the problem happened? Check your FPDM above the spare tire, on the crossmember. They tend to rot out.
I had a very similar issue with mine, luckily turned out to be from my K&N drop in air filter. Was letting a bunch of crap through, and dirtied up the MAF. Actually threw the truck into limp mode.

Deerhunter4

Make sure there is dielectric grease on each COP as well.

On another note. I'm in Amarillo. If you need anything on the way through just let me know. That's quite a drive for any vehicle.

nrivera04

Echlin is Napa's top shelf brand of ignition parts. They're made by Standard who's been around since dirt had a pulse.

When did you change plugs? I would be suspect of one being broken or cracked. It happens frequently and it's been seen here a lot.

powerranger262

Oh man, can a cracked plug ever give you the runaround. Had one on my Ranger. I did a plug change for a misfire. Didn't fix it, and then just proceeded to throw parts at it, thinking, it can't be plugs, they are new.
Finally got a code for a specific cylinder misfire, pulled the plug, and sure as ****, it had a hairline crack in the porcelain.

DanAustin

Thanks yeah I'm leaving a few days in front of him in my 13. I did dielectric grease every cop everything was just changed yesterday it has done it since we bought it 2 months ago just didn't have time to mess with it. We did unplug each one and I ohmed each one it doesn't have any problems doing like a brake stand it will smoke the tires without lugging 0 to wot no stumbles just that little bit when it's lugging before it drops gear at 40 cruising around town it gets annoying. It's not acting like it wants to throw the driveline anymore which is good but it's still there.

DanAustin

We did everything yesterday to try and cure it.