I'm trying to track down a noise on my 2018 F-150 XLT 5.0L (2WD) with about 170,000 miles.
Here are the symptoms.
-Only happens when the engine is cold. Completely goes away once the truck is fully warmed up.
-Most noticeable around 2,000 RPM.
Happens during acceleration through that RPM range
-Sounds like a metallic rapid chatter. Almost like a zip tie or baseball card hitting bicycle spokes.
-I can reproduce it by lightly holding the throttle around 2,000 RPM while in Drive. It doesn't seem to do it at all when just revving in Park.
No noticeable engine vibration, no check engine light, and the truck otherwise runs great.
So far I've considered a loose heat shield or exhaust bracket. (couldn't find anything)
I came across a few posts mentioning spark knock, but since it only happens cold and disappears once everything is hot, I'm not convinced that's it.
Has anyone with a high-mileage 5.0 experienced something similar? If so, what ended up being the cause?
Thanks in advance.