Dizzc

Need some help guys think I have a serious issue. My truck is a 2006 5.4l with 150k miles. I've had the truck for about 6 months and since then it developed a rough idle. Got a couple codes that were misfire cylinder 8, misfire cylinder 1, and misfire on first 1000 rotations. Thought this was just a plugs and coils issue so I replaced both. It didn't do anything for the rough idle but I didn't get any codes for a couple weeks now the codes are back. Same cylinders are misfiring and now I have another code that says random misfire in addition to the others. Also sometimes when I'm accelerating from a stopped position it shudders a bit. And just this morning I went out for a drive and when i first started hitting the gas it really hesitated and almost felt like it was going to die.

So I have tried new plugs, new coils, new fpdm and cleaned the maf and throttle body. What should I be looking for now? Stating to get worried that this engine is toast.
Thanks.

Martian

Clean your throttle body and MAF, check your air filter, get under the truck and take a look at your FPDM above the spare tire (remove it and look at the back).

Dizzc

Sorry I forgot to mention that I have cleaned both the throttle body and maf and replaced my fpdm a couple weeks ago after it corroded right through. Air filter is fine too.

Pmoon

Maybe the throttle position sensor?

Dizzc

I could see that potentially being a fix for the rough idle and shuddering but it probably wouldn't explain the misfiring on those two specific cylinders though right?

commando24

That's happened to me a few times. Replaced the coil pack and I was good to go.

Dizzc

Was hoping that was my issue as well but new coils didn't do a damn thing.

corey_lax

Just because you have new coils and plugs doesn't mean they are functioning properly. Try swapping them with others to see if the engine code moves. If not, you're all good there.

Next replace your fuel filter.

Then, look at injectors.

Dizzc

So I tried swapping the coils around and as expected the misfires remained on the same two cylinders, #1 and #8. Also I got another code, p0175 - system too rich bank 2. Accelerating at low speeds seems to be getting worse. There is a very noticeable mis/hesitation when I hit the gas. Its most noticeable when accelerating from a stopped position.

Should I plan on replacing the injectors next? From what I have been reading it would be extremely unlikely that two injectors would fail in such a close time span.

Do you guys think I should just take it into the shop or is there something else that I could be looking at?

Thanks for the help.

DMTF-22

Having the same issues after doing the same swaps and stuff but not getting anywhere either. I can't even drive mine after the coil/plug swap tho. It almost dies just putting it in drive or reverse. I Need some help on this one too