I know there's already a thread about rattling on acceleration, but I think my problems is different. About a month ago, I noticed a grinding noise when accelerating from a stop. There doesn't seem to be any slipping of gears though, and it doesn't do it if I'm a little easier on acceleration. Most of the time I don't accelerate quickly from a stop anyway, so it doesn't do it 95% of the time. But if I give it a decent amount of throttle from a stop it will make the grind sound for just a fraction of a second. There's no noise after that. Once I get going I can gun it in any gear with no noise. No noise during WOT in any gear, no noise downshifting, and no symptoms of the transmission or torque converter malfunctioning. Also, it won't do it in reverse. It's strong enough that I can feel it through the pedal.

The grind sounds like it could be the engine/transmission flexing due to bad mounts. But I've tightened them all down and it still does it. I suppose one could be going bad. I was thinking heat shields but it doesn't so it at any time when idling in gear or when accelerating slowly where the same frequency of vibration would inevitably occur, causing the noise to surface. It also sounds like it could be a half-shaft slipping? But I'd think I'd notice some sort of RPM increase or having a similar noise on hard acceleration. And I don't know how that would even happening unless the teeth were warped. The torque converter was my first guess - like maybe the stator since it's most functional during initial acceleration. But I'd think I'd see some sort of symptom if that were the case. And after a month, it hasn't gotten any worse or better.

Any ideas?

 

turn off VSA and try again, perhaps the car is picking up wheelspin and limiting power/braking causing the grinding noise

 

Not a bad idea. It does sound similar to when the VSA kicks in. But it still does it with VSA turned off. I'll keep hunting.....