So my truck seems to be misfiring as it has a rough idle (enought to shake the truck, literally) and reduced power. This happened once not too long ago on a very cold night. After idling for 15min the time before I put the truck away and drove the car. Next day truck starts fine, no problems. Started up this evening and rough idling again. Engine light was flashing as is now on. Spark plug? Injector? Cold temps freezing something? Will get code read just don't want to drive it like it is. The truck sits most of the winter. But the two times this has happened has been after below zero nights. Any thoughts?

 

Also the exhaust has a sound like its missing and not the nice V8 rumble.

 

Codes are

P0174 - System too lean bank 2 (O2 sensor?)

P0300 - Random misfire

P0305 - Misfire Cylinder 5 (Plug or Coil?)

Any help where to start looking for repairs?

 

I would look at the coil pack on cylinder 5. Switch it with another cylinder and see if the code moves. If it does...that's your problem...if not, you could have a problem with the plug.

I had a similar scenario on my Expedition and coil pack fixed it right up.

 

Great thanks. Hopefully that works b/c working on the plugs in winter, no thanks. Not to mention how easy it is to pull the plugs out because they don't break off or anything Other opinions or knowledge welcome before I drop money on stuff that doesnt work.

 

A buddy and I just recently did his plugs on his F250 and it wasn't too bad. It took about 4 hours start to finish. There is a decent amount of room to work on the Super Duty trucks.

 

I just had the same exact codes (except for the random misfire) on my 2005 5.4, after changing the coil, plug and fuel filter and cleaning the MAF I still had the same codes. Ended up being the injector on Cyl 5. I would hesitate a guess to say that the lean code and misfire are related, as in the injector is sticking since they're on the same bank. If you have access to a scanner that can read fuel trims that will help you narrow it down a lot more. How many miles though? Maybe the O2 sensors are due anyway?

Mine was covered under Ford's 2005 extended injector warranty but they were quoting another $100 (over the diagnosis fee) to change it before I pushed about the warranty. The injector is only $30-40 though and it didn't look all that hard to change if you wanted to do it yourself. In my case I probably would have been better off to change it myself b/c they still charged me $100 diagnosis fee since they found (or said they did, the light hasn't come back on!) another unrelated code.

 

Good info. Gives me a place to start. Did you have the same rough idling? The truck has almost 70k. Parts are cheap so I don't mind trying different things. Plugs scare me but this needs to get fixed.

 

Actually no, not really - but mine wasn't a constant miss either. They said the injector wasn't completely stuck closed, but it either wouldn't open all the way or just stuck intermittently. You can buy a few parts for what they ususally charge just to hook it up to the computer at the dealer! Just takes more time. The plugs scared me too, I'd read the latest TSB on how to remove them until I could almost recite it from memory but once I started to loosen it it wasn't stuck at all and came right out. I got my truck used with no history but it was a Fleet vehicle and they had already been changed and antisiezed. If your'e the original owner you might not be as lucky. If you're in hurry you can just change #5 and worry about the rest later. As has already been suggested, you can swap coils and see if the problem moves. That's a quick way of narrowing it down farther. It's my understanding that O2 sensors should be good for 100,000 or there abouts so I would still say the lean code and misfire are connected. Of all the parts the coil and 02 sensor are probably the most expensive - but also the easiest to change. If you have a mechanics stethescope you might be able to listen to the injector on Cyl 5 and see if you can hear it opening. As far as I know though, the only sure fire way of narrowing it down farther is hooking it up and getting the fuel trims. I'm not a mechanic by any means though just repeating what I've learned on here and my own recent experience. Maybe someone more knowledgeable can chime in?

Honestly if you're scared of the plugs (but from what I can tell it's best to change them sooner rather than later) and it's not the coil I think I'd just swap out the injector, it really doesn't look all that hard to get to, just a couple bolts and the driver side fuel rail is loose. But i've never changed one myself so it might be more complicated than it looks.

 

I'm not necessarily scared to do anything just know that it could be a PITA. I'm not in need of the truck right now so I do have some time to get things done. I just need a taller garage!! That truck wont fit in there and with winter still in full swing this wont be easy. I've thought about doing the plugs anyways just to get it done before it needs to be done.

Mine definitely idles rough, especially when put into D or R or any other gear. I'll keep narrowing it down and hopefully fix things. The 05 F150 I had suffered a similar problem but it completely shut down and wouldnt even start. That was a completely shut injector.

 

Well, that helps explain the misfires I'm seeing on my truck on cylinders 3 and 8. It could be the same cause. I'm going ahead with the O2 sensor and fuel filter change just to be safe, then I'll recheck the codes.

 

Papa J - I see you have a 2005, if it's a 5.4 and if it does turn out to be injectors remember there's an extended warranty on that year out to 120,000mi, not sure if it covers the 6.8 or not. With 2 cyl's missing it might be worth it to spend the $ to have the dealer hook it up and see if it is the injectors. If it is it shouldn't cost you a thing. If you need a copy of the letter ford sent out explaining the extended warranty let me know - I had to push back a little at the dealer to make them cover mine.

Just realized 3&8 are on opposite sides, are you getting lean codes on both sides or just one?

 

So i swapped coil packs from cylinder #5 (problem cylinder) to #1 cylinder. Still getting P0174 and P0305 (misfire) and rough running at idle and cruising at 60mph. I guess my other options are fuel inector or spark plug. I have a reader and can get info such as fuel trims. Just have no clue what I am looking for in them. Any help or insight appreciated. My next try would be fuel injector. Just trying to go from simple (coils) to hardest (plugs).

 

I'm not a tech and haven't sprung for a service manual yet so I can't tell you off the top of my head. Here's a couple links I used when I was trying to diagnose mine, hopefully they'll help. Maybe just scan it and post the results here, hopefully somone more knowledgable than me will chime in - you might also ask in the 2004-2008 F150 forum, there seems to be more 3v 5.4 guys in there than in the Superduty forum.

https://www.ford-trucks.com/forums/8...ode-p0506.html

https://www.ford-trucks.com/forums/9...-replaced.html

 

ive had the same problem on the same engine except i had both banks lean, what i ended up doing after testing the coils and came back good was just doing the plugs and all 8 injectors. it costed me a total of 275 all my plugs came out easy some were even loose. for the same job at the dealer would of costed 1780. but all in all it fixed the truck and i no longer have the tick. also what i would recommend is take a stehascope along the fuel rails and when you get closer to the cylinder that is missing see if you can hear a louder tick. if so it might be an injector stuck open or closed. or if you dont like the tick go ahead and replace the injectors anyways i bought my injectors from parts guy ed for 196 shipped and my plugs from orileys auto parts for they have platnum motorcraft plugs. but if i where you thats where i would start job from start to finish was around 5 hours.