Hey guys I have a 2002 f250 5.4 4r100 142k miles no cat flow master super 44. Truck was used as a farm truck prior to my purchase with regular maintenance. Runs smooth and has good power.
it does have the regular 5.4 2v noises including piston slap on warm up. It does go away upon touching the throttle and most away at idle after warm. But what Im concerned about is the piston slap noise at idle after a long stretch of driving highway speeds. After driving long distances and coming to an idle the idle is very loppy like a small block with a mild cam. Doesn't shake the whole truck or anything but the noise is present. It's not super loud but noticeable. If it idles for a minute or 2 it'll pick up idle and smooth out like the timing changes and make no noise at all. This was present before and after installing the flow master and removing the cat. I use only name brand gas. No noises during driving only at idle. No codes except a bank 1 knock sensor circuit malfunction I had to dig for in my scanner which i suspect is partially the cause of the problem. I read a thread of a guy with a v10 with similar problems replacing his and it solved his issue. Ive looked for exhaust leaks an been all over it with a stethoscope with no exact diagnosis. Am I tripping over normal 5.4 noises or am I about to be shelling out money for a new short block? I'd appreciate any advice or stories with similar experiences.

 

Are you sure the noise you are hearing isn't just pinging? I'd imagine that the engine would ping pretty badly if the knock sensor wasn't operating...If it were me, I'd ensure the knock sensor wiring was good first. If checks out, make sure the knock sensor connector is on and not broken. If that's good, go ahead and replace the sensor.

 

Try cleaning your Idle Air Control valve before you replace any parts.

 

It could very well be. I thought this as well since IIRC the ecm has a timed strategy for pulling timing after a set amount of time as a safe guard against detonation. Basically a count down in my understanding. I need to replace the intake anyway as it started leaking a couple of months ago at the water jacket area like most do. I couldn't find a certain answer but is there only one KS or is there 2, 1 per cylinder bank?

 

will do. I plan on hosing the MAF as well with maf cleaner.

 

On my old 2002 F150 with the 5.4 it would usually have a rough hot idle when the IAC valve would get dirty. It's not the easiest design to clean so I think I ended up replacing it. Sorry about 10 years ago so my memory is a little foggy.

 

no worries. I havent had a chance to mess with it for a couple days due to working 12s at work. But I did crank it the other night and once again listen for the noise. Runs very well and the noise wasn't present for more than a few minutes then disappeared. I've listened all over the block heads and timing chain cover and can't pin it. Only thing I can 100% hear is loud injectors. I will try to clean the iac when I'm off and see how it works. But I kinda feel like I'm getting pinging when I come off a long drive from high cylinder Temps and it cools slightly or timing changes when it idles and it settles down. At this point I'm not really worried but it is however annoying as hell. This is my second modular and my 09 2v 4.6 isn't near as noisy and it has nearly 40k more miles