It's been going on for a while now.
She jerks and lurches, and generally runs rough on normal - mild driving.
On acceleration, she's fine, but only as long as there's boost.

What the heck could be wrong?
Any idea's?

 

How many miles? Mods? Any more info?

I'd say first check plugs. Check fuel filter. Try a fuel injector cleaner/ing. Make sure maf is connected, if so make sure maf is working. Try resetting the computer.

 

the only mods are a Diablo chip, and K&N cone filter.
16,000K
I've run injector cleaners, taken the chip out (runs worse), and looked everywhere.

Can't figure it out.

 

bad coil pack or clogged fuel filter. Try replacing fuel filter first, they should be changed every 10k (max.) anyway.

 

Hey Seattle..I know what you mean man..Thats how mines running and i have the very same mods. It runs rough and without a certain amount of boost in low RPMs it takes a good while for the truck to move than usual..Mines been doing this for 10K miles and my truck now has 60K on it.. I've tried everything I could think of and that everyone has suggested.. So don't feel like yours is the only L that runs like Sh#%... So does mines..
What i'm gonna do is take my truck to a performance shop only that has a good dyno machine and also give them the NA L specs so they can compare them to yours.. Specs like Air/Fuel mix, compression at idle etc., Fuel pressure, boost, any other stock specs you can think of.. I'm gonna let them detect whats lacking and fix the restriction... Let me know if you find something...Who knows we could have the same problem...

 

mine did it too way back not long after i had it. replace the coil pack on the #4 cylinder. it has a heater hose that drips water on it and shorts it out. if its not that coil i bet you it is another. mine ran fine when u mashed on it but it ran terrible at normal driving. by the way ford dealers obviously cant tell that there is a bad coil. i had to take mine in 3 times and they never did fix it so i fixed it myself. a good friend of mine is an excellent mechanic and he suggested that coil so we tried it and it runs like a top now and ever since.

 

Hey Rusty, How much did the coil pack run you? and also did you notice any kinda misfiring or extreme skipping before you changed the coil? Mines not skipping but like yours, through normal driving it was horrible but when you mash it jets out..I just figured that a bad coil pack would cause the truck to skip or misfire at idle or during acceleration..If thats not the case, that could possibly solve my problem...Thanks!!!!!

 

Since you have a K&N filter, check/clean the MAF sensor wire and the IAT sensor wire. Sometimes the K&Ns shed oil and it can coat the sensors.

Dan

 

hey im not sure bout the cost its been so long ago. the only way i could tell mine was skipping was at round 35 mph maintaining that speed it had a bumpy road feeling. just a little buck, bump, buck. not too big a deal but it ran like crap the whole time. it was only when i was maintaining that speed i believe round 1200 rpms. i think cost of my mechanic and coil and all was 80 bucks.

 

LightninRod is on to something there, most people "over-oil" thier filters. What year is your truck out of curiousity? I would first change the fuel filter

 

RUSTY,
Thanks man, I knew someone on this board had to have had the same problem.
I am afraid of Dealers, as I have never had a good experience with them.
I'm going to check into the coil pack scenerio and see if that fixes this.
By the way, you described my symptoms to the T.

 

anytime seatlle in my case it was the #4 coil it could be a different one for you so be aware. but please keep me informed email me or something so i find out if it helped. i hope it does.

 

Hey Rusty, Do you know if a test can be run on a coil pack to find out which # may be damaged? Or did you just take a chance with trial and error?

 

i just took a chance and tried the #4 based on my mechanics hunth of the heater hose dripping water on it. only reason he knew this was b/c his expedition did it to him. my problem was everyonce in a while it would work ok. 95% it ran terrible.

 

ok thanks Rusty..I noticed that also that sometimes the truck would run like new and then back to riding sluggish again..Are the packs specific for each spark plug or can you replace a coil pack with any new one?