Hi All,

Trying to help a friend again. 2005 V8 with ~215,000 miles. Yesterday was driving along and the truck started riding rough "sputtering". Flashing CEL, VSC TRAC, etc. lights come on. She had it towed, I met up and pulled the codes. I initially got P0305 and P0174. Cleared the codes then took it for a test drive to see if I could duplicate. Even idling it felt like it was missing and on the drive the lights flashed on but went off. When I pulled the codes again, only P0305 showed up (no P0174) I told her that I would change the spark plugs/wires (she has NEVER had these replaced!) this weekend.

My concern is that she is terrible about doing maintenance other than oil changes every 4-5k miles, she's done nothing else! So I have read a few posts on here, is this the start of a bigger problem? Am I just changing the plugs in hopes of getting it trade in-able? I had driven the truck a month or so ago and thought I felt a slight miss then but no CEL or anything.

Feel free to tell me I'm being paranoid and just change the plugs! By the way is there a plugs/wires writeup. Seems simple enough but I like to have visual aids. Thanks!

P0174 "System too lean, bank 2"
P0305 "Cylinder 5 misfire"

These 2 codes together don't make much sense to me; cylinder 5 isn't even in bank 2! Since P0174 didn't return after you cleared it, I'd start by solving the cyl 5 misfire first.

Inspecting/changing plugs (no wires, it's COP) is probably a good step if no routine maintenance has been performed lately (spark plug service interval is 120k for our fancy iridium plugs). Even better, you could swap the coil from cylinder 5 with a different cylinder and see if the P030x code follows that coil.

How long has it been since any routine service has been performed? These T4Rs are stone cold dependable, but parts designed to be replaced every 30k miles (or whenever) will eventually wear out...

I'd check the factory service intervals and see what major components/systems need service by now, then determine if the cost to do so is worth keeping the truck. At the very least try to explain the importance of routine maintenance; it's just as critical as oil changes. For example, it might be expensive but a timing belt job now is a lot cheaper than a new engine in 10k miles if the belt snaps and the pistons hit the valves. That also applies to just about every major system on the car that's been neglected.

Beyond that I don't think your codes are indicative of a deeper, more insidious problem. P0306 on a V6 can often mean head gasket leak, but that's very rare on the V8. If you bring the truck up to date on maintenance, you shouldn't have anything to worry about.

Thanks for the info! So no wires? Nice. Just coil packs then? I know T4R are beast but when I say she's never had any maintenance...I really mean never. Just oil change when she can, tires when they're bald and brakes when they wail. Bought it with like 50k miles on it I think and 215k now. She drives for work maybe 600+ miles a week.

So I'm heading over tomorrow to change the plugs. She got Denso irridiums (at least I told her to). Someone please tell me these are pregapped because I don't have a tool for that. Will take over a bottle of seafoam too. She also bought new boots, should those need to be replaced?

Yes I had been telling her about the timing belt, water pump, etc. (Which has never been done) and I was just about to send her a link for the kit when this happened. Will take one step at a time and get this done see what happens and then the TB service.

Thanks again for the feedback. Will post up how things turn out.

Oh and I thought the P0174 code was weird too but since it didn't come back I didn't worry about it. I think I got that code on my 3rd gen when my 02 sensor went bad.

Holy cow looking at it this seems like a really easy job. However none of the videos I saw did anyone use antiseize. What's up with that?

Just to update...I went over and changed out the plugs with Denso irridiums. The #5 coil pack looked a mess so replaced that too (the #5 plug looked much worse than the others). Only negative is the dealer didn't have any coil packs so ended up getting a Napa Denso unit. I know...but it was the only option today. Forgot to take the Seafoam so that will have to wait.

So far cleared the codes, let it run a bit then took it for a long mixed test drive. So far so good. Runs much quieter, smooth no misfires and no codes! Yes! Told her to keep an eye on it and let me know if anything pops up.

Thanks for all the info. This forum rocks!

Hello All - the P0174 code has shown back up. If I understand this is most likely the O2 sensor right? Is bank 2 the downstream sensor? Dealer wants $285 plus 1.5hrs of labor. I say no way! Appreciate any feedback.