2005 F-150 4.6L 2WD
268,000 miles

Recently I got a flashing 'Check Engine' light and a rough running engine (along with a tapping noise) when I was passing someone (and pulling a trailer). I retrieved codes 300, 304, & 305. I can't swear to it, but I think the tapping noise started at the same time as the coil problem.

I replaced coils #4 & #5 (later that same day) and the engine smoothed back out but the tapping noise is still hanging around. The noise speeds up at higher RPM's and doesn't go away if I shift into neutral. Oil level and pressure are fine and I only use Motorcraft 5W-20 and Motorcraft filters (and change the oil every 5K miles).

Not sure if this is relevant: I think I have bad valve guide seals (blue smoke after long idles) but no other problems that I am aware of.

It sort of sounds like a lifter, but is there a good way to pin it down? Is it possible that this tapping is related to the bad coils?

Thanks in advance for your help.

 

My '07 had a noise similar to what you describe, ticking at all rpms, sounding like a lifter. Using a stethoscope I narrowed the source of the noise to the front 2 cylinders on my passenger side. After pulling the valve cover I found one of the followers had seized and galled cam lobe. I replaced the cam and the seized follower and all is well. If yours turns out to be this issue, it's an easy repair, but you will need a couple of specialized tools. Oh, and mine never gave a check engine.

 

Did you also replace the lifters or just the one bad rocker arm and cam?

 

I left the lifters, they were fine. It was the seized follower that was the cause of my problem. It's an easy fix, but it has quite a few steps involved.

 

HEY GUYS I THOUGHT THAT YOU SAID THAT YOU REPLACED THE CAM AND A FEW LIFTERS, DID I READ IT CORRECTLY? MY EXPERIENCE IN THE WORLD OF RACING IS THAT YOU NEVER REUSE OLD LIFTERS ON A NEW C AM AND YYOU NEVER MIX THEM UP FROM THE HOLES THAT THEY CAME OUT OF. AS I RECALL FROM HEARING "THE RACING HERO'S FROM MY PAST TALK" YOU CAN USE NEW LIFTERS ON AN OLD CAM BUT YOU CAN'
T USE OLD LIFTERS ON ON A NEW CAM. I THINK THATS WHAT I REMEMBER.

 

I replaced the bad seized followers, left the lifters. Remember, this is not like the pushrod, cam in the block. This is overhead cam, the "lifters" (called lash adjusters) are never in contact with the cam, the followers are. The followers are what seized up, causing galling of a couple of the lobes.