[kyle797]

I have a noise between 2200 and 2800 rpm truck must be under heavy load most noticeable when pulling trailer. It sounds like pre ignition or a loose rattling part. All heat shields are good if i bang on the ex i do not hear any loose parts rattling truck has 135k both manifolds have 60k on them no visible or audible ex leaks when noise occurs their is no lack of performance no check engine errors bank 1 and bank 2 o2 very close to each other within 1% at about 110% to 113%. so any ideas on how to determin if i have a knock issue? a cat core loose in the housing or something else

 

[kyle797]

also have run multiple bottles of fuel system cleaner through and high octane fuel neither made a difference

 

[LUBECAKES]

Mine does this, same noise from old exhaust system to new exhaust system. I've repaired or removed shields, but it persists. I recently discovered my shield under the bed was loose at one bolt, but haven't had the time yet.

 

[Walrus]

Hood is closing tightly?

 

[kyle797]

hood is tight going to put it on dyno to further diag