Knocking under load

[CrimsonEclipse]

Whenever I was towing a trailer and/or a hot day, I would hear pinging (detonation?) under the hood. It would be lessened with 89 octane and eliminated with 92 octane. Is there a timing issue with my engine?

2003 B2300 4 banger.

CE

 

[Beanmachine7000]

No timing issue... It's more than likely just carbon buildup inside your combustion chamber...