Hey everyone! new here so if i somehow break any rules i’d like to apologize early on for that.


Recently i’ve found that my 08 F-150’s engine (5.4 3v with 252,000km of 156,000 miles) has the notorious “knocking + ticking sound”

Ive been doing as much diag as i can (+ bringing my truck into the shop for the last week) to try and atleast pinpoint what was specifically causing the issue, and i just wanted to run something by yall before i do anything too crazy.

Symptoms:
- Only when driving around for 20-30min, cold start there’s 0 noises whatsoever
- Knocking/ticking sound from 800-1200rpm, i can still hear the ticking sound upwards of 1500rpm, but it’s faint so i’m thinking i’m just hearing the injectors at that point
- No performance issues whatsoever, truck still takes off and drives like a dream, but with a rough idle between 550-650rpm’s

So far i’ve changed the ignition system, and i’ve been doing oil changes early (3000 miles or 5000km, i’m canadian) with 5W-20
Ive been doing a bunch of reading on my shop’s scan tool and haven’t found anything that raised any alarms, 0 DTC’s whatsoever, and even the Cam Phaser live data seems relatively in spec.

I know the truck has a couple exhaust manifold studs that have been sheared off, I can’t seem to understand why and how that would cause a rough idle. (To explain, at idle it feels like there’s a bunch of small misfires, you can even hear it with the hood popped open as well as feel it in the truck itself)

So far misfire-wise, the scan tool has picked up on nothing. When running a cylinder contribution test, holding at 2000rpm all cylinders would equal out to 0, which tells me that they’re doing fine. At idle they would randomly dip to -2 before coming straight back up so i don’t think that could be an issue (i could be wrong)
Ran a compression test and all cylinders were fine, vacuum and air intakes fine, etc etc

I would greatly appreciate any help/advice i could get, even though I love the experience i think i’ve bitten off more than i can chew lol.

Ive attached two photos of the Variable Cam data, one with idle rpm and one with roughly 1500rpm.

 

If you have knocking and rattling phasers, replace them then recheck the codes
You will have a rash of codes and drivability issues with failing phasers
Keep in mind the system uses oil pressure to retard the cams
If you are low on oil pressure the problem gets more serious
maybe replace the oil pump while you do the timing chain and tensioner job with the new phasers
A Melling HV oil pump sometimes helps

 

Just a comment, food for thought. I have heard of cases where the timing chain is worn and slaps the cover

 

Well you want to look at mode six ,it tells you by cly the number of raw computer counts toward setting a code . Setting a code the level of misfires is quite high to set it . You want zero counts . You are in the zone of of needing a timing job at 156k miles . What happens is the oil pressure is too low to drive the phasors , many times its the plastic tensioners on the chain ,the gasket on them lets go and dumps the oil straight to the crankcase . At the same time the tension on the chain is gone so the chain loosens up allow timing to jump teeth on the phasor . The chain can whip and break the plastic guides , the chain can start grinding on the aluminum timing cover on the inside . The plastic guides pieces will fall into the gears and get ground up into fibers , the fibers will get sucked up into oil pickup blocking flow .
So you can tell alot by dropping oil pan and checking it out and cleaning everything .
When you do A timing job its better to use a new melling hv oil pump . Also use the old style ratcheting tensioners with no gaskets to blow out . Some guys cut some of the teeth on the ratchet so it will not lock on high oil pressure . .
At idle misfires show up the worst if its a vacuum leak . At high rpms vac leaks don't cause much of a problem . The best test for vac leak is a diy smoke machine off youtube . Spark related misfires show up at 45mph especially climbing a grade . Spark plugs should be changed every 60k . Spark plug boots around 125k even if they look good . Clean all cop tabs and connectors ,tabs get corroded scrape that off . Oem cops are the best ,thats why they cost 60 apiece .
Most of us use 5w-30 in warm climates . I do an engine flush every other oil change . IF your oil gets sludge it wont operate phasors correctly . Best to change Vcts out every 100k or so . Clean oil galleys and system's are key as it hydraulically operates engine with dirty engine oil . Canada engines condense water in crankcase on short trips since it doesn't have a chance to ventilate . Some of these engines get so bad that the valve train looks like solid chocolate cake frosting -nothing works good in that . Change oil more often. run it enough to vent engine .use the lower viscosty in winter by your avg temps. then flush it , I use motor medic from walmart . Yeah I know how it is to lay in snow working on engines -no fun .
Keep oil system clean to the max -once it clogs up its too late .
Your exhaust leaks can effect your fuel mix since it is in front of your o2 sensor , the maf measures the amount of air going in , the o2 measures the amount of oxygen in exhaust to adjust feul ratio by the length of the fuel pulse in milliseconds allowed on the injectors - it is constantly adjusting those . The o2 signal is a small sine wave as it overshoots and corrects each way .
If you do timing job you must drop the oil pan and clean every thing .

 

First - thank you redfishtd for a through write up!
your statement "If you do timing job you must drop the oil pan and clean every thing " is very important. The fibers and debris get sucked up against the oil pump suction screen and most of it will fall away from the screen when the pump is idle (engine not running). When you have the opportunity to clean the pump make sure you clean the covered area below the pickup screen as that debris is very hard to see and can get overlooked causing future problems.