I've searched the forums, but have yet to come across a thread that matches the niggling little issue that's recently come up with my car. So here's an invitation to some brainstorming until I'm able to swing by the friendly neighborhood mechanic later in the week. My '03 CL-S has recently developed a faint grinding or rattlling that rears its ugly head during mild/moderate acceleration into the VTEC engagement range (3500 rpm). It sticks around for about another 2,000, after which point I won't say it disappears because it's possible that it's being masked by the exhaust and other sounds and motions inherent to high RPM operation. I haven't identified any other detriments; no warning lights, the car seems to still pull strongly, and fuel use is steady. Still, I'm not sold on this being right or normal. I've made plenty of gradual runs into VTEC, and I can't recall hearing or feeling anything more profound than the exhaust during the changeover until now.

For perspective's sake, the drivetrain is stock save for an '07 Accord automatic in lieu of my original transmission, which joined the Doomed Patrol about three months ago with horrid slippage in 3rd-5th gear. The car has 133,000+ miles, and is current on all Acura-perscribed service and maintenance. Interestingly, this issue became apparent to me immediately after having the stock rims replaced by Motegi Racing MR121s. . .