I noticed a slightly rough ride around 70-80 mph sometimes on interstate a month back but thought it was my scalloped tires that need replacing and ignored it. Last weekend i had to go to MI from GA pulling a small enclosed tandem axle trailer (6x12). I started after work and made it to VA before stopping for the night with no problems not even at 70-80. Fueled up first thing in the morning (BP Fuel) and headed farther into the mountains when the truck started shaking when it should be downshifting (into overdrive im guessing?) No check engine light come on so i pulled off the road checked rearend and motor oil everything was fine, topped off tranny which was slightly low but was on dipstick .I let the truck cool for 20 min then got back going again. I continued driving with overdrive off, and not ******* on the truck. Everytime it had to downshift under hillclimb it would start shaking but i would let out of the gas and it would stop. Once i got out of the mountains it was fine and couldnt tell it was running bad at low rpms, and also drove fine when i got off the interstate for fuel driving in towns.

I drove that whole day through ohio mich and back trough ohio when entering kentucky. It started to downshift and run at high rpms with no problem, and started acting up when i got back into the mountains.When the truck would go to downshift it started to shake uncontrolably again. then is when the check engine light come on and flashed. i babyed in until tenn when i stopped at oriellys to hook up to scanner. scanner read misfire on 5 and ignition coil d primary secondary circuit malfunction. I checked the #5 plug (fine) and replaced the #4 coil, and didnt check the #4 plug like an idiot. kept going and it never fixed the problem. stopped and jumped my coils around and check a few more plugs which all were fine but never that #4 (why idk), after being fed up, sat night, no mechanics around and wanting to get home i drove it the rest of the way. it never idled rough until i got almost home in Ga. When i got home the next day i pulled all plugs and all looked brand new still except the #4 which had the whole prong and tip completely burnt off. I replaced it and nothing changed, but my exhaust sounded restricted. Brought to a shop and it is now reading a misfire on 4 (with brand new plug) 5 7 and 8 and also saying it is running lean. They changed fuel filter and plugs but nothing still. Other than the fact i brought my truck to a retarted mechanic what do you think?


04, f150, 4.6, 4x4, stx, short wheel base, 3:55

 

Potentials and clarification ....

you currently have codes P0304, P0305, P0306, P0307, P0308 and a lean code. What is the lean code? P0170 or P0171? Or both?

If you have all of those misfire codes then it looks like your entire second bank isn't firing. There are only so many things which will cause that, and the main ones which come to mind are base engine timing and a bad (plugged) catalyst.

Experience has shown me that both bad cats and out of time engines can give false rich or lean codes. It's possible but unlikely that the chain on the left side just up and skipped a tooth, so I'd start toward the exhaust possibility.

The faulty primary coil circuit will obviously cause a lack of fire on #4. The flashing check engine light is for a 'catalyst damaging misfire', and even though #4 is on the opposing bank of cylinders I would still lean toward an issue with your exhaust system as a result of the misfire.

Temporarily remove both upstream 02 sensors from the y-pipe. Does it run any better?

 

Well i work out of town and dropped the truck off at a shop in town that was highly recommended and they have been jerking me around all week. I don't know the exact codes because the only ones i saw were the misfire on 5 and ignition coil D when i checked them in tennessee. I am taking monday off of work to go get my truck and have a word with the guy. He is the one who pulled all the other codes, and ill try to figure out exactly which ones they were. The check engine light did flash a couple times during my trip, and i was thinking it was the cat, just didn't know how to diagnose. Monday am going to pull those upstream O2 sensors, but what do i look or listen for when i do? Also the exhaust did sound restricted before i dropped it off, and when i was driving it home i stomped of the gas and it ran fine at really high rpms (guessing it was forcing the exhaust through the cat)(I didn't do that often, just once to see what it would do) thanks for the help ill let you know monday morning my results

 

hey i got the truck and it is running good after all new plugs, and the lean code is bank 1 (P0171) My book doesn't show a P0170 at all. The truck seems to be mechanically running fine, it seems to be only (shaking) so to say or running rough when idling at stoplights, or low rpm cruising…?