Knock in v4 mode only

[14silveradomike]

Hey everyone. So today my 2014 Silverado with 5.3 and 57 thousand miles on it. Started a nasty knock when it drops down into v4 mode. Truck runs great in v8 no check engine light or anything. Couldn’t find any one else with problems like this. Dealer can’t get the truck in till 2 days from now and the advice guy said it could be the exhaust also.

[flyingfool]

what's the KR reading on the scan tool while it makes this noise?

[16K2XX]

KR as in knock reading?

[flyingfool]

knock/reetard  had to miss spell it due to censoring the word r***rd

Edited September 6, 2020 by flyingfool

[FlatRater]

Going off the complaint alone I have to guess VLOM and or AFM lifters failing. This is common. I just did a set on a 2016 L83 last week for this same issue.