I have a 2001 Infiniti I30 and I was at an intersection when I initially noticed a slapping sound coming from my vehicle; lowered the radio, and lowered windows to ensure that I was the culprit; also noticed that the noise would become greater when I lightly press the gas as I was in stop and go traffic... I was worried so I kept driving and found an open stretch of road and floored it; As I picked up speed, the noise eventually went away, and I did not encounter it again during my drive home; hope its a one time thing, but mostly likely a signal of something more ominous

For context, I did add some Gumout Multi-System Tune-Up gas treatment two weeks ago, and still burning through that tank of gas; kinda regret adding it

 

check the engine oil level before anything

 

Yeah...will definitely check the oil; believe there's a rear main seal leak and I'm supposed to periodically add oil

 

I'm totally using this diagnostic approach before anything else next time

 

I wanted to refrain from commenting. I have a suspicion he's going to find nice metal chunks in the oil.

 

Mech changed out both of my drive belts....so wiill see if noise arises again

 

keep us posted