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LT4 valve train or fuel injectors on cold startup?

jwolf99

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Joined
Jan 28, 2021
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577
Location
New York
V-Series Cadillac(s)?
2022 CT5-V Blackwing
Any one else notice that a loud tapping or ticking on the LT4 valve train or fuel injectors upon cold start? At first I thought it was one of the pulleys upon hearing from inside the car. But with hood open and ability to get near source, it definitely seems to be coming from either valve train or fuel injectors. It immediately quiets down to an almost undetectable level after ~30 seconds. Also, non existent on warm/hot restarts.

Take a listen and let me know you thoughts. @Mirza Grebovic?

 
Any one else notice that a loud tapping or ticking on the LT4 valve train or fuel injectors upon cold start? At first I thought it was one of the pulleys upon hearing from inside the car. But with hood open and ability to get near source, it definitely seems to be coming from either valve train or fuel injectors. It immediately quiets down to an almost undetectable level after ~30 seconds. Also, non existent on warm/hot restarts.

Take a listen and let me know you thoughts. @Mirza Grebovic?

Sounds like an exhaust leak
 
Sounds like the high pressure fuel pump and injectors for warming up the cats on cold start for emissions. A lot of cars I've owned have that ticking sound and is especially noticeable on startup.
 
Sounds like the high pressure fuel pump and injectors for warming up the cats on cold start for emissions. A lot of cars I've owned have that ticking sound and is especially noticeable on startup.
This! Sounds is normal.
 
HPFPs are notoriously noisy... I have to say the LT4 has one of the quietest I have ever heard. The HPFP on my mazdaspeed3 made it sound like I had constant lifter tick. Actually, there were a lot of cases where DI cars were taken back to the dealer with concerns that there were problems with the motor just to find out it is normal.
 
I was kind of figuring (hoping) it was fuel delivery related. My 2009 CTS with 3.6L DFI was noisy as well, including after start up.

Thanks for all of the responses so far.
 

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