Gen 3 2022 Engine Bay Clatter

My truck started clattering on cold start ups and settles down after a minute or so. 28k miles now and the noise wasn't there a few months ago but has started doing this fairly recently. The noise is coming from near the top passenger side of the engine. After a minute or so the noise quiets down and is hard to hear after that. I was at the dealer last week for other work and asked them to take a listen and on start up sure enough the clatter was there. The shop foreman went over to a 23 model with 15k ish miles and it did the same thing on start up. It is definitely engine speed related it changes speed when the engine does, and there are times when a switch or valve shifts with a click and the clatter calms down a lot. The foreman suggested it might be the fuel pump, but I question that because it is engine speed related. The dealer said they are checking into it. Has anyone else seen this issue?

 

Could well be the fuel pump... not the electric low pressure fuel pump in the tank but the high pressure fuel pump under the hood. It is mechanically driven by gears off the camshaft so will react to engine speed. This is a common "issue" on many direct injection engines.

 

If you're an old school shade tree mechanic like I am and equate "noise = something going wrong", then it takes time to get used to the clatter/chatter noise of direct injection at (and following) start up. Especially during a cold start up.

It's probably just the direct injection mechanical noise you hear, but if you can post a cold start video with the hood up then we can help weigh in.

 

The sound you are hearing is most likely the D4S fuel injection system. When first started, particularly when engine is cold, it runs on direct injection mode for several seconds very rich using very high pressure which makes a significant amount of buzz or clatter. It then switches to port injection and quiets down. Normal operation.

This is done momentarily on a cold start by many manufacturers to help warm and fire off the catalytic converters downstream of the engine quicker for reducing emissions.

 

Awesome responses and makes total sense. Didn’t know it had a direct injection pump. Thanks for the feedback.

 

V35A engine has direct and port injection, switches back and forth depending on operation conditions. The cam lobe driven high pressure pump is on the passenger side valve cover. Characteristically makes quite a racket when developing high pressure similar to diesel fuel injections systems.