Have a bit of a head scratcher for you this morning, as my mechanic and I have been trying to figure this out for three weeks.
2002 330i - automatic. She currently is sitting at 187k miles. While in gear (drive and reverse) and idling there is a strong vibration in steering wheel and through cabin.
Rpm’s are sitting right at 600-650. No codes are being thrown or stored.
When gas is applied and rpm’s go above 700, vibration essentially disappears.
Motor and trans mounts replaced around 120k and look almost new with no signs of wear or leaks.
We have smoke tested it twice, and also sprayed two cans of brake cleaner, absolutely zero vacuum leaks.
Disa taken out, and gas upgrade kit 5k miles ago
Spark plugs replaced with NGK iridium, and coil packs replaced with Bosch plugs.
Intake boot replaced, throttle body and IAC cleaned.
Harmonic balancer checked and within oem spec
Pressure tested all cylinders, all cylinders sit within 170-175 psi with 2% differential between each.
Borescoped each cylinder, there is no scoring and can even see slight cross hatching still.
At this point, we are stumped. The only thing I can even think it can be is something fuel related. My mechanic thinks it’s something electronic.
Any ideas?