[guitarlover9182]

First post! Will do my best to be succinct and descriptive.

2008 BMW 550i Manual Transmission - Stock, no modifications, No CEL's

Hesitation: Let out clutch fully and coast at 750-1k RPM. WOT results in lurching/lagging/surging acceleration until it reaches 1500-2000 rpms then it takes off. No hesitation or hiccups past that point. Idle is smooth. Can rev engine in neutral to 6k RPMs with no issue.

Maintenance
- New plugs
- Coils less than 30k miles (tested coils with voltmeter)
- New PCV valve
- New MAF
- Fuel system cleaner
- Intake manifold cleaned
- New Flywheel and Clutch
- New Guibo
- New trans mounts
- Inspected Cats - clean mesh (unplugged O2 sensors as well to test)
- Trans fluid flush
- Differential fluid flush


Knocking/Slamming Noise: Under hard acceleration in 1st/2nd there is a repeated knocking noise. This is a new symptom after recently changing the flywheel, clutch, guibo, and trans mounts. I removed the exhaust down to the cats and it is still happening (not flexing/hitting exhaust pipes). Recorded GoPro under car. Seems to be coming from front. Could be motor mounts (possible damage during trans maintenance). Tested engine movement with emergency brake on and trying to let clutch out and accelerate. Not much movement but may not be enough torque to manifest a broken mount. Checked all bolts (trans mounts, driveshaft bolts, etc) and all is tight. Looking for ideas.

I plan to post video footage soon via YouTube links. Any help would be appreciated.