[mjfulk]

Im experiencing an intermittent rattle/knock from the engine bay (on the drivers side) when accelerating between 3k to 4.5k rpm. I've been unable to replicate the noise when in neutral and free raving the engine. It tends to occur when the engine is warm, never when cold. Sometimes I'll go a day without any issues and other days I'll hear it almost everytime I accelerate regardless of which gear. I have a 2014 MT fr-s with 70k on the OD. Mods include a drop in filter, catted ft-86 header, and OFT tune. I purchased the vehicle used with 62k mile and the noise was present when the vehicle was stock so it doesn't appear to be related to any of the mods. No other issues when it's making the noise, power loss or the like. It doesn't appear to be rod knock (not metallic sounding). Others have posted identical description of the issue but have not commented on a cause and or fix. I want to chalk it up to a noise these engines make but it appears to be happening more frequently which concerns me. Doesn't have the load pop associated with DI seal issues and only happens under load. If it's the valve timing, as some have speculated, why is it intermittent and present with or without the tune? It's loud enough passengers have asked what it is which tells me again it's not normal boxer sound.

I've spent hours trolling other posts and again it doesn't appear I'm the only one experiencing this problem. However I've yet to hear from anyone who has diagnosed/resolved it. I'm getting increasingly frustrated with it and would appreciate if anyone has experience with a similar issue and what came of it.

One last observation, when it's making the noise the engine sounds slightly rough when cruising at engine speads below 3k RPM. Hard to describe the rough sound but kind of like a faint rattle. On days I'm not experiencing the acceleration knock this rough sound isn't there.

Sent from my HTC6545LVW using Tapatalk