I have read the forum on the rattle during acceleration. However, my rattle only occurs when the vehicle has been driven for 15 to 20 min. And then only under acceleration. In park, while reving the engine, the noise is not there. Driving slowly, like through a parking lot the noise goes away. It only occurs after sometime dring and under accleration. Every shop that I have taken it to has no idea what it is. I have switched to Cheveron's 91 gas and had an oil change (5w30) but still the noise persists. Anyone have any ideas? I read where someone might think it was the manifold but wouldnt that make noise even in park? My exhust was checked out with nothing to fix. I am going crazy with this noise. [:@]

 

Is it spark knock?

 

Well as an update,; I have filled up with 91 octane @ Chevron and also added a bottle of STP octane boost. THe knock has been removed so I guess it was spark knock. However, I cannot afford to constantly purchase both gas and octane booster. Is there a fix for this problem? Is it a winter thing? (is there a winter in southern Arizona?) Any ideas are welcome.