let us know what u figure out.

 

I'm wondering by reason thing if I'm having the same problems. Replaced the coils and spark plugs. Took it out yesterday and noticed right at 50 & 75mph it felt sluggish. Like my engine would shake as if it was misfiring & wouldn't want to accelerate, No CEL though.

 

ABSOLUTE FRUSTRATION!!! Guys I'm back to the drawing board on my truck. I've spoken to a couple of mechanics and got this blank stare from both. I've got one more to try Monday (guy I've known for years) and hope he has some idea. Everybody keeps telling me to change this and that but only because they don't have a clue what to do.

I did a vacuum test this morning and it was good and steady. Cannot for the life of me get this thing to throw any more codes. Cylinder misfires have been random (8 then 4 then 6). Due to the random nature I've ruled out fuel injector, cop or plug problem (when pulled each has been good). Fuel filter has been changed, MAF cleaned (again), PCV valve changed. Slightly rough at idle but when put in gear and driven with slight load misfires and hesitates so bad it will shake your fillings loose and still no code. Going up a hill is the roughest ride you can imagine. When there is no load it smooths out considerably.

I'm a shade tree mechanic at best but if a certified mechanic looks at me with a blank stare what the heck am I supposed to do? This truck ran absolutely great until it hit 138k miles. I know there has to be something I can do without throwing money at parts just for the heck of it.

Sorry for venting...

 

Bump. Sorry for the bump but I'm back to the drawing board. Several guys have tried to help and it is much appreciated. If any news ideas I'm all ears. Thanks

 

fuel pump...

 

I cleaned the maf before and I made it worse. It could be the problem. I noticed these trucks are very finicky. look for any loose or corroded grounds.

I spent hours trying to figure out my truck and it definitely gets maddening

 

Same boat here 127k plugs,maf and (cops have been changed and now my truck shakes worse. I did find that the first plug near the radiator on drivers side was loose and not seated well and screw was loose. I am all out of money and ideas trying to get this effin truck to just run right.

 

I put a set of Motorcraft SP-479 plugs in my S'crew two weeks ago because I was having a misfire under moderate load(highway speeds in overdrive). I believe my original problem was due to some oil spilling into the number 1 plug well - found that when I went to change the plugs. This past week I started having a more severe misfire (under light loads such as accelerating from a stop) when the truck was cold (temps were in the 20's F most of the week). The truck doesn't seem to have as much power as it did before even when it is not misfiring.
My previous sparkplugs were NGK Platinum 3403 which had about 48K miles on them and were put in with new Global cops. For the record I had one Global cop fail within six months but the others were doing fine. I'm wishing I had went with the same plugs now. The NGK's have a slightly longer insulator on top which may make a better connection with the spring and the center electrode has a much finer wire which I think fires better. I think my next step will be to try a full set of new cops just in case one is going bad. I double checked all my electrical plugs today just in case that was my problem.

 

There's just know way you could have not figured out why you truck is running this way, IF you've done everything mentioned. No way in hell.

 

same 40 - 50 mph shutter

07 5.4 l flex w/39,000 miles

just changed plugs w/e3 a month ago and switched cop's w/GMS...

problem started Friday...pulled all GMS cop'f off and re-installed factory cop's
over the same spark plug it came from...same problem!!!

checked all cop bolts...checked all connections...cleared all old codes...

only dove it for about 10 minutes and code P 0358 came up...

is that the #8 (drivers/rear) cylinder misfire???

I need to drive more for more codes...do I need to check plugs too???

 

What's GMS ? Granitelli ?

 

http://www.granatellimotorsports.com...cks-318-0.html

 

Yea, that's what I said lol.

 

also...fyi...

I have a volant CAI...replaced fuel filter about 7k ago...and run fuel system cleaner twice a year when I change the oil...

on my way to advane auto for maf cleaner and QD electtric parts cleaner...

also is the cylinder order from front to back

pass 1-2-3-4
driver 5-6-7-8

 

What do you mean "IF"? You have some reason to doubt that I'm doing what I said? Not sure how to take your comments but it's not coming across very well.