Chased a lean condition for a while, finally changed the cops, truck ran awesome for a few months. Now I'm getting p0174 and p0301 codes. Flat roads im good, but pulling a trailer or any incline and it starts shuddering and popping the 301. I know what they mean, any help in chasing them down? O2 sensors? Cat? Intake leak? Injections? I changed the plug in cylinder 1 buy hasn't made a difference it was fouled pretty good.

Thanks in advance.

 

Bad cop or injector in #1.

The K&N and the tunes are probably making it run too lean unless they are custom tunes specifically for a K&N.

 

Put a couple bottles of chevron techron or gumout with PEA in it and see if that helps clean the injectors.

 

Your initial lean issue was probably from the K&N joke. They're not a great addition and all they achieve is a lot of noise under the hood. Your truck already came with a cold air intake capable of more air than the engine can use. But now you have a fouled plug. More than likely you have a vacuum leak somewhere. I'd be looking at the PCV hose, if it has one. They're a known issue with holes in it. You may have a non-Motorcraft PCV which can also screw things up. Use ONLY Motorcraft parts on the engine or expect issues. If the O2 sensors haven't been replaced and the truck has 75,000 miles or more on it, it's past due. Use only Motorcraft sensors as they are tuned specifically for the PCM. If the O2 sensors read a lean exhaust, the PCM will increase the fuel/air ratio hence the fouled plug. I'd be checking the plugs on the same side. More than likely the closer you get to the firewall the leaner the plugs are going to read. If so, replace the entire PCV system.

 

Exhaust leaks before the upstream O2 sensor can also trip a lean code and richen it too much.

 

K and n will be out no longer have tunes all motorcraft parts just driving me nuts I'll check again for vacuum leak but didn't find any the last time 300k it's done me good tho

 

Labnerd, the 5.4 3 valve doesn't have a PCV valve. It's a fixed orifice in the valve cover.

 

to clarify, had the truck since 2008 had the plugs done a 3rd time 12 months ago, coils done 2 months ago, and truck ran great not lean codes nor misfire on cylinder 1. started again 2 weeks ago. ill change the filter out and see but im thinking its not the only issue....O2 and maybe a vaccum leak, maybe bad injector as plug was fowled pretty bad when i changed it out

 

Drove it to work today, after installing new air filter, cleaned MAF just to be safe and resetting the computer. On the highway hitting the throttle truck started to vibrate, codes popped, p0174 bank 2 lean, one set code on pending, p0301 misfire cylinder 1 and p0316. Going to take it in, new injector and plug on cylinder 1 and it sounds like a exhaust leak around the drivers side cat, could that be triggering the lean on that bank? And thanks fellas for the input if ya have anything else please let me know I'm desperate. Just bought the ole lady a new explorer and can spring on a new truck til spring time.

 

If you have an exhaust leak around the cat, they may be starting to plug up. I'd get them checked.

 

Was thinking that, so thursday im taking it in for new injector and another new plug on cylinder 1. I popped the coils off of number 1 and 2 and swapped them, no change. I just have my fingers crossed it isn't going to end with catastrophy.... still hoping that the injector is failing, causing the misfire, and i kill both those birds with that stone and MAYBE its an exhaust leak causing the lean condition on bank 2.

Funny that after doing all the coils it ran great for a few weeks, i changed them because of a lean condition and now its running like crap, if not worse than before assuming the misfire on number 1 is the culprit on that end tho.

Any other suggestions while we have it on the Operating table?

 

Just an update, new injector put in road tested same issue. Hesitation and threw codes, back in shop after noticing a "rattle" gutted cat blew it out road test and ran like a champ. So not knowing if it was the injector or not but definitely was q plugged cat

 

What plugs are you using? I used E3's for 2 months. Got a mis fire on #1 on the way to work. On the way home I got random mis fires on multiple cylinders. Took all the plugs out and went back with Motorcraft. #3 plug was destroyed.

 

It was the cat as far as I can tell only use motorcraft parts